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See detailThiamine triphosphate: a ubiquitous molecule in search of a physiological role
Bettendorff, Lucien ULg; Wins, Pierre

in Metabolic Brain Disease (in press)

Thiamine triphosphate (ThTP) was discovered over 60 years ago and it was long thought to be a specifically neuroactive compound. Its presence in most cell types, from bacteria to mammals, would suggest a ... [more ▼]

Thiamine triphosphate (ThTP) was discovered over 60 years ago and it was long thought to be a specifically neuroactive compound. Its presence in most cell types, from bacteria to mammals, would suggest a more general role but this remains undefined. In contrast to thiamine diphosphate (ThDP), ThTP is not a coenzyme. In E. coli cells, ThTP is transiently produced in response to amino acid starvation, while in mammalian cells, it is constitutively produced at a low rate. Though it was long thought that ThTP was synthesized by a ThDP:ATP phosphotransferase, more recent studies indicate that it can be synthesized by two different enzymes: (1) adenylate kinase 1 in the cytosol and (2) FoF1-ATP synthase in brain mitochondria. Both mechanisms are conserved from bacteria to mammals. Thus ThTP synthesis does not seem to require a specific enzyme. In contrast, its hydrolysis is catalyzed, at least in mammalian tissues, by a very specific cytosolic thiamine triphosphatase (ThTPase), controlling the steady-state cellular concentration of ThTP. In some tissues where adenylate kinase activity is high and ThTPase is absent, ThTP accumulates, reaching ≥ 70% of total thiamine, with no obvious physiological consequences. In some animal tissues, ThTP was able to phosphorylate proteins, and activate a high-conductance anion channel in vitro. These observations raise the possibility that ThTP is part of a still uncharacterized cellular signaling pathway. On the other hand, its synthesis by a chemiosmotic mechanism in mitochondria and respiring bacteria might suggest a role in cellular energetics. [less ▲]

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See detailIn search of a physiological role for thiamine triphosphate and the 25-kDa thiamine triphosphatase
Bettendorff, Lucien ULg; Lakaye, Bernard ULg; Kohn, Grégory ULg et al

Conference (2014, May 25)

In search of a physiological role for thiamine triphosphate and the 25-kDa thiamine triphosphatase L. BETTENDORFF, B. LAKAYE, G. KOHN AND P. WINS GIGA-Neurosciences, University of Liège, 4000-Liège ... [more ▼]

In search of a physiological role for thiamine triphosphate and the 25-kDa thiamine triphosphatase L. BETTENDORFF, B. LAKAYE, G. KOHN AND P. WINS GIGA-Neurosciences, University of Liège, 4000-Liège, Belgium Thiamine triphosphate (ThTP) was discovered over 60 years ago. Although it is present in most organisms from bacteria to mammals, its possible biological functions remain unclear. In contrast to thiamine diphosphate (ThDP), it is not a coenzyme. In E. coli cells, ThTP is transiently produced in response to amino acid starvation, while in mammalian cells, it is constitutively produced at a low rate. In some animal tissues, ThTP was able to phosphorylate proteins and activate a high-conductance anion channel in vitro. These observations raised the possibility of ThTP being part of a still uncharacterized cellular signaling pathway. Though it was long thought that ThTP is synthesized by a specific ThDP:ATP phosphotransferase, more recent studies indicate that two main mechanisms are involved: (1) in the cytosol adenylate kinase 1 can catalyze ThTP production from ThDP and ADP and (2) in brain mitochondria FoF1-ATP synthase can catalyze ThTP production from ThDP + Pi. The latter reaction is energized by the respiratory chain through a chemiosmotic mechanism analogous to oxidative phosphorylation. Both mechanisms are conserved from bacteria to mammals. While ThTP synthesis does not seem to require a specific enzyme, its hydrolysis in mammalian tissues is catalyzed by a very specific cytosolic 25 kDa thiamine triphosphatase (ThTPase). Because of this activity, steady-state ThTP levels are kept low in mammalian cells. ThTPase belongs to the CYTH superfamily of proteins which has representatives in all superkingdoms of life acting on tripolyphosphate and various triphosphorylated substrates. Although the whole chromosome region containing the ThTPase gene was lost in birds, orthologs of the ThTPase gene were found in all other known metazoan genomes. It seems that ThTPase activity appeared as a secondary acquisition of the CYTH proteins in the lineage leading from cnidarians to vertebrates. In particular, the Trp-53 residue of mammalian ThTPases plays a key role in substrate recognition and specificity by interacting with the thiazole part of ThTP. This residue is conserved in metazoan CYTH proteins with ThTPase activity. In order to gain insight into the physiological function(s) of the ThTP-ThTPase couple, we tried to produce a mouse invalidated in 25-kDa ThTPase. Surprisingly, we were unable to obtain any knockout animal, apparently because ThTPase seems to be required for spermatogenesis. As we previously showed that the enzyme is much more abundant in differentiated versus undifferentiated cells, we suspect that 25-kDa ThTPase might play a more general and important role during cell differentiation. Acknowledgments This work was supported by the F.R.S.-FNRS. LB and BL are respectively Research Director and Research Associate at the F.R.S.-FNRS. [less ▲]

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See detailBiological functions of thiamine derivatives: Focus on non-coenzyme roles
Bettendorff, Lucien ULg; Wins, Pierre

in OA Biochemistry (2013), 1(1), 10

Thiamine (vitamin B1) is mainly known for its diphosphorylated derivatives (ThDP), an essential coenzyme in energy metabolism. However non-coenzyme roles have been suggested for this vitamin for many ... [more ▼]

Thiamine (vitamin B1) is mainly known for its diphosphorylated derivatives (ThDP), an essential coenzyme in energy metabolism. However non-coenzyme roles have been suggested for this vitamin for many years. Such roles have remained hypothetical, but recent data from various sources have shed a new light on this hypothesis. First, the existence of other phosphorylated thiamine derivatives, most prominently thiamine triphosphate (ThTP) and adenosine thiamine triphosphate (AThTP) can reach significant levels in E. coli, respectively during amino acid starvation and energy stress. Though much less is known about these compounds in animals, mammalian cells contain a highly specific soluble thiamine triphosphatase controlling cytosolic ThTP concentrations. Second, there is now growing evidence in favour of the existence of thiamine-binding proteins with specific roles in the nervous system, possibly in the regulation of in neurotransmitter release. Thiamine and some of its synthetic precursors with higher bioavailability have beneficial effects in several models of Alzheimer’s disease and may be beneficial for patients suffering from Alzheimer's or Parkinson's diseases. These effects might be related to non-coenzyme roles of thiamine, possibly involving thiamine-binding proteins. [less ▲]

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See detailBiochemistry of thiamine and thiamine phosphate compounds
Bettendorff, Lucien ULg; Wins, Pierre

in Lennarz, W. J.; Lane, M. D. (Eds.) The Encyclopedia of Biological Chemistry, vol 1 (2013)

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See detailAn alternative role of FoF1-ATP synthase in Escherichia coli: synthesis of thiamine triphosphate
Gigliobianco, Tiziana ULg; GANGOLF, Marjorie ULg; Lakaye, Bernard ULg et al

in Scientific Reports (2013), 3(1071),

In E. coli, thiamine triphosphate (ThTP), a putative signaling molecule, transiently accumulates in response to amino acid starvation. This accumulation requires the presence of an energy substrate ... [more ▼]

In E. coli, thiamine triphosphate (ThTP), a putative signaling molecule, transiently accumulates in response to amino acid starvation. This accumulation requires the presence of an energy substrate yielding pyruvate. Here we show that in intact bacteria ThTP is synthesized from free thiamine diphosphate (ThDP) and Pi, the reaction being energized by the proton-motive force (Dp) generated by the respiratory chain. ThTP production is suppressed in strains carrying mutations in F1 or a deletion of the atp operon. Transformation with a plasmid encoding the whole atp operon fully restored ThTP production, highlighting the requirement for FoF1-ATP synthase in ThTP synthesis. Our results show that, under specific conditions of nutritional downshift, FoF1-ATP synthase catalyzes the synthesis of ThTP, rather than ATP, through a highly regulated process requiring pyruvate oxidation. Moreover, this chemiosmotic mechanism for ThTP production is conserved from E. coli to mammalian brain mitochondria. [less ▲]

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See detailThiamine triphosphatase and the CYTH family of proteins
Bettendorff, Lucien ULg; Wins, Pierre

in FEBS Journal (2013), 280(24), 64436455

The CYTH superfamily of proteins was named after its two founding members, the CYaB adenylyl cyclase from Aeromonas hydrophila and the human 25 kDa THiamine triphosphatase (ThTPase). Members of this ... [more ▼]

The CYTH superfamily of proteins was named after its two founding members, the CYaB adenylyl cyclase from Aeromonas hydrophila and the human 25 kDa THiamine triphosphatase (ThTPase). Members of this superfamily of proteins exist in all organisms including bacteria, archaea, fungi, plants and animals (except birds) and can be traced back to the Last Universal Common Ancestor. Their sequences include several charged residues involved in divalent cation and triphosphate binding. Indeed, all members of the CYTH family that have been characterized act on triphosphorylated substrates and require at least one divalent metal cation for catalysis. In most cases, the enzyme-substrate complex adopts a tunnel-like (ß-barrel) conformation. The Nitrosomonas europaea and E.coli CYTH proteins are specific inorganic triphosphatases. We propose that inorganic triphosphate, the simplest triphosphate compound, is the primitive substrate of CYTH proteins. Other enzyme activities such as adenylate cyclase (in A. hydrophila and Y. pestis), mRNA triphosphatase (in fungi and protozoans) and ThTPase (in metazoans) are secondary acquisitions. ThTPase activity is not limited to mammals, but sea anemone and zebrafish CYTH proteins are already specific ThTPases and the acquisition of this enzyme activity is linked to the presence of a Trp (W53 in mammalian ThTPases) residue involved in the binding of the thiazole heterocycle of the thiamine molecule. Furthermore, we propose a conserved catalytic mechanism between a bacterial inorganic triphosphatase and metazoan ThTPases, based on a catalytic dyad comprising a Lys and a Tyr residue, explaining the alkaline pH optimum of these enzymes. [less ▲]

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See detailCritical Review: Biological functions of thiamine derivatives: Focus on non-coenzyme roles
Bettendorff, Lucien ULg; Wins, Pierre

in OA Biochemistry (2013), 1(1), 10

Thiamine (vitamin B1) is mainly known for its diphosphorylated derivatives (ThDP), an essential coenzyme in energy metabolism. However non-coenzyme roles have been suggested for this vitamin for many ... [more ▼]

Thiamine (vitamin B1) is mainly known for its diphosphorylated derivatives (ThDP), an essential coenzyme in energy metabolism. However non-coenzyme roles have been suggested for this vitamin for many years. Such roles have remained hypothetical, but recent data from various sources have shed a new light on this hypothesis. First, the existence of other phosphorylated thiamine derivatives, most prominently thiamine triphosphate (ThTP) and adenosine thiamine triphosphate (AThTP) can reach significant levels in E. coli, respectively during amino acid starvation and energy stress. Though much less is known about these compounds in animals, mammalian cells contain a highly specific soluble thiamine triphosphatase controlling cytosolic ThTP concentrations. Second, there is now growing evidence in favour of the existence of thiamine-binding proteins with specific roles in the nervous system, possibly in the regulation of in neurotransmitter release. Thiamine and some of its synthetic precursors with higher bioavailability have beneficial effects in several models of Alzheimer’s disease and may be beneficial for patients suffering from Alzheimer's or Parkinson's diseases. These effects might be related to non-coenzyme roles of thiamine, possibly involving thiamine-binding proteins. [less ▲]

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See detailStructural Determinants of Specificity and Catalytic Mechanism in mammalian 25-kDa Thiamine Triphosphatase
Delvaux, David; Kerff, Frédéric ULg; Murty, Mamidanna R.V.S. et al

in Biochimica et Biophysica Acta - General Subjects (2013), 1830

Background: Thiamine triphosphate (ThTP) is present in most organisms and might be involved in intracellular signaling. In mammalian cells, the cytosolic ThTP level is controlled by a specific thiamine ... [more ▼]

Background: Thiamine triphosphate (ThTP) is present in most organisms and might be involved in intracellular signaling. In mammalian cells, the cytosolic ThTP level is controlled by a specific thiamine triphosphatase (ThTPase), belonging to the CYTH superfamily of proteins. CYTH proteins are present in all superkingdoms of life and act on various triphosphorylated substrates. Methods: Using crystallography, mass spectrometry and mutational analysis, we identified the key structural determinants of the high specificity and catalytic efficiency of mammalian ThTPase. Results: Triphosphate binding requires three conserved arginines while the catalytic mechanism relies on an unusual lysine-tyrosine dyad. By docking of the ThTP molecule in the active site, we found that Trp-53 should interact with the thiazole part of the substrate molecule, thus playing a key role in substrate recognition and specificity. Sea anemone and zebrafish CYTH proteins, which retain the corresponding Trp residue, are also specific ThTPases. Surprisingly, the whole chromosome region containing the ThTPase gene is lost in birds. Conclusion: The specificity for ThTP is linked to a stacking interaction between the thiazole heterocycle of thiamine and a tryptophan residue. The latter likely plays a key role in the secondary acquisition of ThTPase activity in early metazoan CYTH enzymes, in the lineage leading from cnidarians to mammals. General significance: We show that ThTPase activity is not restricted to mammals as previously thought but is an acquisition of early metazoans. This, and the identification of critically important residues, allows us to draw an evolutionary perspective of the CYTH family of proteins. [less ▲]

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See detailHigh inorganic triphosphatase activities in bacteria and mammalian cells: Identification of the enzymes involved.
Kohn, Grégory ULg; Delvaux, David ULg; Lakaye, Bernard ULg et al

in PLoS ONE (2012), 7(9), 43879

Background: We recently characterized a specific inorganic triphosphatase (PPPase) from Nitrosomonas europaea. This enzyme belongs to the CYTH superfamily of proteins. Many bacterial members of this ... [more ▼]

Background: We recently characterized a specific inorganic triphosphatase (PPPase) from Nitrosomonas europaea. This enzyme belongs to the CYTH superfamily of proteins. Many bacterial members of this family are annotated as predicted adenylate cyclases, because one of the founding members is CyaB adenylate cyclase from A. hydrophila. The aim of the present study is to determine whether other members of the CYTH protein family also have a PPPase activity, if there are PPPase activities in animal tissues and what enzymes are responsible for these activities. Methodology/Principal Findings: Recombinant enzymes were expressed and purified as GST- or His-tagged fusion proteins and the enzyme activities were determined by measuring the release of inorganic phosphate. We show that the hitherto uncharacterized E. coli CYTH protein ygiF is a specific PPPase, but it contributes only marginally to the total PPPase activity in this organism, where the main enzyme responsible for hydrolysis of inorganic triphosphate (PPPi) is inorganic pyrophosphatase. We further show that CyaB hydrolyzes PPPi but this activity is low compared to its adenylate cyclase activity. Finally we demonstrate a high PPPase activity in mammalian and quail tissue, particularly in the brain. We show that this activity is mainly due to Prune, an exopolyphosphatase overexpressed in metastatic tumors where it promotes cell motility. Conclusions and General Significance: We show for the first time that PPPase activities are widespread in bacteria and animals. We identified the enzymes responsible for these activities but we were unable to detect significant amounts of PPPi in E. coli or brain extracts using ion chromatography and capillary electrophoresis. The role of these enzymes may be to hydrolyze PPPi, which could be cytotoxic because of its high affinity for Ca2+, thereby interfering with Ca2+ signaling. [less ▲]

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See detailMolecular evolution of the CYTH superfamily of proteins
Bettendorff, Lucien ULg; Delvaux, David ULg; Kohn, Grégory ULg et al

in FEBS Journal (2012), 279(Suppl. s1), 438

Molecular evolution of the CYTH superfamily of proteins L. Bettendorff, D. Delvaux, G. Kohn, P. Wins, B. Lakaye GIGA-Neurosciences, University of Liège, Belgium The CYTH superfamily of proteins was named ... [more ▼]

Molecular evolution of the CYTH superfamily of proteins L. Bettendorff, D. Delvaux, G. Kohn, P. Wins, B. Lakaye GIGA-Neurosciences, University of Liège, Belgium The CYTH superfamily of proteins was named after the two founding members, the CYaB adenylyl cyclase from Aeromonas hydrophila and the human 25-kDa THiamine triphosphatase (ThTPase). Members of this superfamily of proteins exist in all organisms including bacteria, archaea, plants and animals (except in birds) and can be traced back to the Last Universal Common Ancestor. They are characterized by a consensus sequence including several charged residues involved in divalent cation and triphosphate binding. Indeed, all members of the CYTH family that are characterized act on triphosphate derivatives and require at least one divalent cation for catalysis. The Nitrosomonas europaea (1) and E.coli CYTH proteins are specific inorganic triphosphatases. We propose that inorganic triphosphate (PPPi), the most simple triphosphate compound that can be imagined, is the primitive substrate of CYTH proteins. Other enzyme activities such as adenylate cyclase (in A. hydrophila), mRNA triphosphatase (in fungi and protozoans) and ThTPase (in metazoans) activities are secondary acquisitions. We show that ThTPase activity is not limited to mammals, but Sea anemone and Zebrafish CYTH proteins are already specific ThTPases and the acquisition of this enzyme activity is linked to the presence of a Trp (W53 in mammalian ThTPases) residue involved in the binding of the thiazole heterocycle of the thiamine molecule. The importance of W53 for the specificity of mammalian ThTPases is confirmed by site-directed mutagenesis. Furthermore, we propose a conserved catalytic mechanism between inorganic triphosphatases and ThTPases, based on a catalytic dyad comprising a Lys and a Tyr residue, explaining the alkaline pH optimum of CYTH proteins. (1) Delvaux et al. J. Biol. Chem 286 (2011) 34023-35 [less ▲]

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See detailThiamin derivatives in the brain of a mouse model of Alzheimer's disease and in cultured Neuroblastoma cells treated with benfotiamine
Vignisse, Julie ULg; Liégeois, Jean-François ULg; Wins, Pierre et al

Poster (2011, July)

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder for which any disease-modifying treatment is available. It is estimated that approximately 36 million people suffer from this disease ... [more ▼]

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder for which any disease-modifying treatment is available. It is estimated that approximately 36 million people suffer from this disease and it comes with a high prize for the society. Recently, it has been shown that chronic administration of benfotiamine, a precursor of thiamin, in a mouse model of AD (APP/PS1 mice) significantly reduced key features of this disease namely memory impairment, β-amyloid accumulation and tau hyperphosphorylation. These beneficial effects are thought to be mediated by the PI3K/Akt/GSK3 signalling pathway (Pan et al., 2010). GSK3 is a kinase involved in the tau protein hyperphosphorylation in Alzheimer’s disease. It is however not clear how and which thiamine derivatives could interact with this kinase. Thiamine diphosphate is a well-known co-factor, in particular for mitochondrial pyruvate and oxo-glutarate dehydrogenases. However, other derivatives such as thiamine triphosphate and the newly discovered adenosine thiamine triphosphate are investigated in our laboratory. Therefore, we shall first try do determine whether benfotiamine (or one of its degradation products) or one of the above-mentioned thiamine derivatives are directly or indirectly involved in the regulation of the PI3K/Akt/GSK3 pathway in cultured neuroblastoma cells. For this purpose, neuroblastoma 2a cells will be grown in a thiamine-deficient medium containing benfotiamine, and thiamine derivatives (thiamine mono-, di- and triphosphate) will be measured by HPLC whereas Akt and GSK3 expression and phosphorylation levels will be assessed by immunoblotting. These experiments will give us new insights into the mechanism of action of thiamine derivatives, and according to the results obtained, we could then design new synthetic derivatives that would be more efficient than benfotiamine (very high doses were required in the animal experiments) in slowing down the neurodegenerative processes in Alzheimer’s disease. [less ▲]

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See detailA specific inorganic triphosphatase from Nitrosomonas europaea: structure and catalytic mechanism
Delvaux, David ULg; Murty, Mamidana R.V.S; Gabelica, Valérie ULg et al

in Journal of Biological Chemistry (2011), 286

The CYTH superfamily of proteins is named after its two founding members, the CyaB adenylyl cyclase from Aeromonas hydrophila and the human 25-kDa thiamine triphosphatase. Because these proteins often ... [more ▼]

The CYTH superfamily of proteins is named after its two founding members, the CyaB adenylyl cyclase from Aeromonas hydrophila and the human 25-kDa thiamine triphosphatase. Because these proteins often form a closed β-barrel, they are also referred to as “Triphosphate Tunnel Metalloenzymes” (TTM). Functionally, they are characterized by their ability to bind triphosphorylated substrates and divalent metal ions. These proteins exist in most organisms and catalyze different reactions, depending on their origin. Here we investigate structural and catalytic properties of the recombinant TTM protein from Nitrosomonas europaea (NeuTTM), a 19-kDa protein. Crystallographic data show that it crystallizes as a dimer and that, in contrast to other TTM proteins, it has an open β-barrel structure. We demonstrate that NeuTTM is a highly specific inorganic triphosphatase, hydrolyzing tripolyphosphate (PPPi) with high catalytic efficiency in the presence of Mg2+. These data are supported by native mass spectrometry analysis showing that the enzyme binds PPPi (and Mg-PPPi) with high affinity (Kd < 1.5 μM), while it has a low affinity for ATP or thiamine triphosphate. In contrast to Aeromonas and Yersinia CyaB proteins, NeuTTM has no adenylyl cyclase activity, but it shares several properties with other enzymes of the CYTH superfamily, e.g. heat-stability, alkaline pH optimum and inhibition by Ca2+ and Zn2+ ions. We suggest a catalytic mechanism involving a catalytic dyad formed by K52 and Y28. The present data provide the first characterization of a new type of phosphohydrolase (unrelated to pyrophosphatases or exopolyphosphatases), able to hydrolyze inorganic triphosphate with high specificity. [less ▲]

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See detailThiamine Status in Humans and Content of Phosphorylated Thiamine Derivatives in Biopsies and Cultured Cells
Gangolf, Marjorie ULg; Czerniecki, Jan; Radermecker, Marc ULg et al

in PLoS ONE (2010), 5(10), 13616

Background Thiamine (vitamin B1) is an essential molecule for all life forms because thiamine diphosphate (ThDP) is an indispensable cofactor for oxidative energy metabolism. The less abundant thiamine ... [more ▼]

Background Thiamine (vitamin B1) is an essential molecule for all life forms because thiamine diphosphate (ThDP) is an indispensable cofactor for oxidative energy metabolism. The less abundant thiamine monophosphate (ThMP), thiamine triphosphate (ThTP) and adenosine thiamine triphosphate (AThTP), present in many organisms, may have still unidentified physiological functions. Diseases linked to thiamine deficiency (polyneuritis, Wernicke-Korsakoff syndrome) remain frequent among alcohol abusers and other risk populations. This is the first comprehensive study on the distribution of thiamine derivatives in human biopsies, body fluids and cell lines. Methodology and Principal Findings Thiamine derivatives were determined by HPLC. In human tissues, the total thiamine content is lower than in other animal species. ThDP is the major thiamine compound and tissue levels decrease at high age. In semen, ThDP content correlates with the concentration of spermatozoa but not with their motility. The proportion of ThTP is higher in humans than in rodents, probably because of a lower 25-kDa ThTPase activity. The expression and activity of this enzyme seems to correlate with the degree of cell differentiation. ThTP was present in nearly all brain and muscle samples and in ~60% of other tissue samples, in particular fetal tissue and cultured cells. A low ([ThTP]+[ThMP])/([Thiamine]+[ThMP]) ratio was found in cardiovascular tissues of patients with cardiac insufficiency. AThTP was detected only sporadically in adult tissues but was found more consistently in fetal tissues and cell lines. Conclusions and Significance The high sensitivity of humans to thiamine deficiency is probably linked to low circulating thiamine concentrations and low ThDP tissue contents. ThTP levels are relatively high in many human tissues, as a result of low expression of the 25-kDa ThTPase. Another novel finding is the presence of ThTP and AThTP in poorly differentiated fast-growing cells, suggesting a hitherto unsuspected link between these compounds and cell division or differentiation. [less ▲]

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See detailThiamine triphosphate synthesis in rat brain occurs in mitochondria and is coupled to the respiratory chain
Gangolf, Marjorie ULg; Wins, Pierre; Thiry, Marc ULg et al

in Journal of Biological Chemistry (2010), 285

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See detailThiaminylated adenine nucleotides — chemical synthesis, structural characterization and natural occurrence
Frederich, Michel ULg; Delvaux, David ULg; Gigliobianco, Tiziana ULg et al

in FEBS Journal (2009), 276(12), 32563268

Thiamine and its three phosphorylated derivatives (mono-, di- and triphosphate) occur naturally in most cells. Recently, we reported the presence of a fourth thiamine derivative, adenosine thiamine ... [more ▼]

Thiamine and its three phosphorylated derivatives (mono-, di- and triphosphate) occur naturally in most cells. Recently, we reported the presence of a fourth thiamine derivative, adenosine thiamine triphosphate (AThTP), produced in E. coli in response to carbon starvation. Here, we show that the chemical synthesis of AThTP leads to another new compound, adenosine thiamine diphosphate (thiaminylated ADP, AThDP), as a side product. The structure of both compounds was confirmed by mass spectrometry and 1H-, 13C- and 31P-NMR and some of their chemical properties were determined. Our results show an upfield shifting of the C-2 proton of the thiazolium ring in adenosine thiamine derivatives compared to the conventional thiamine phosphate derivatives. This modification of the electronic environment of the C-2 proton might be explained by a through-space interaction with the adenosine moiety, suggesting an U-shaped folding of adenosine thiamine derivatives. Such a structure where the C-2 proton is embedded in a closed conformation can be located using molecular modeling as an energy minimum. In E. coli, AThTP may account for 15% of total thiamine under energy stress. It is less abundant in eukaryotic organisms, but is consistently found in mammalian tissues and in some cell lines. Using a HPLC method, we show for the first time that AThDP may also occur in small amounts in E. coli and in vertebrate liver. The discovery of two natural thiamine adenine compounds further highlights the complexity and diversity of thiamine biochemistry, which is not restricted to the cofactor role of thiamine diphosphate. [less ▲]

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See detailThiamin diphosphate in biological chemistry: new aspects of thiamin metabolism, especially triphosphate derivatives acting other than as cofactors
Bettendorff, Lucien ULg; Wins, Pierre

in FEBS Journal (2009), 276(11), 2917-2925

Prokaryotes, yeasts and plants synthesize thiamine (vitamin B1) via complex pathways. Animal cells capture the vitamin through specific high-affinity transporters essential for internal thiamine ... [more ▼]

Prokaryotes, yeasts and plants synthesize thiamine (vitamin B1) via complex pathways. Animal cells capture the vitamin through specific high-affinity transporters essential for internal thiamine homeostasis. Inside the cells, thiamine is phosphorylated to higher phosphate derivatives. Thiamine diphosphate (ThDP) is the best-known thiamine compound for its role as an enzymatic cofactor. However, besides ThDP, at least three other thiamine phosphates occur naturally in most cells: thiamine monophosphate (ThMP), thiamine triphosphate (ThTP) and the recently discovered adenosine thiamine triphosphate (AThTP). It was suggested that ThTP has a specific neurophysiological role, but recent data are in favor of a much more basic metabolic function. During amino acid starvation, Escherichia coli accumulate ThTP possibly acting as a signal involved in the adaptation of the bacteria to changing nutritional conditions. In animal cells, ThTP can phosphorylate some proteins, but the physiological significance of this mechanism remains unknown. AThTP, recently discovered in E. coli, accumulates during carbon starvation and might act as an alarmone. Among the proteins involved in thiamine metabolism, thiamine transporters, thiamine pyrophosphokinase and a soluble 25-kDa thiamine triphosphatase have been characterized at the molecular level, in contrast to thiamine mono- and diphosphatases whose specificities remain to be proven. A soluble enzyme catalyzing the synthesis of AThTP from ThDP and ADP or ATP has been partially characterized in E. coli, but the mechanism of ThTP synthesis remains elusive. The data reviewed here illustrate the complexity of thiamine biochemistry, which is not restricted to the cofactor role of ThDP. [less ▲]

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See detailAdenylate Kinase-Independent Thiamine Triphosphate Accumulation under Severe Energy Stress in Escherichia Coli
Gigliobianco, Tiziana ULg; Lakaye, Bernard ULg; Makarchikov, Alexander F et al

in BMC Microbiology (2008), 8

BACKGROUND: Thiamine triphosphate (ThTP) exists in most organisms and might play a role in cellular stress responses. In E. coli, ThTP is accumulated in response to amino acid starvation but the mechanism ... [more ▼]

BACKGROUND: Thiamine triphosphate (ThTP) exists in most organisms and might play a role in cellular stress responses. In E. coli, ThTP is accumulated in response to amino acid starvation but the mechanism of its synthesis is still a matter of controversy. It has been suggested that ThTP is synthesized by an ATP-dependent specific thiamine diphosphate kinase. However, it is also known that vertebrate adenylate kinase 1 catalyzes ThTP synthesis at a very low rate and it has been postulated that this enzyme is responsible for ThTP synthesis in vivo. RESULTS: Here we show that bacterial, as vertebrate adenylate kinases are able to catalyze ThTP synthesis, but at a rate more than 106-fold lower than ATP synthesis. This activity is too low to explain the high rate of ThTP accumulation observed in E. coli during amino acid starvation. Moreover, bacteria from the heat-sensitive CV2 strain accumulate high amounts of ThTP (>50% of total thiamine) at 37 degrees C despite complete inactivation of adenylate kinase and a subsequent drop in cellular ATP. CONCLUSION: These results clearly demonstrate that adenylate kinase is not responsible for ThTP synthesis in vivo. Furthermore, they show that E. coli accumulate large amounts of ThTP under severe energy stress when ATP levels are very low, an observation not in favor of an ATP-dependent mechanisms for ThTP synthesis. [less ▲]

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See detailDiscovery of a natural thiamine adenine nucleotide
Bettendorff, Lucien ULg; Wirtzfeld, Barbara; Makarchikov, Alexander F et al

in Nature Chemical Biology (2007), 3(4), 211-212

Several important cofactors are adenine nucleotides with a vitamin as the catalytic moiety. Here, we report the discovery of the first adenine nucleotide containing vitamin B1: adenosine thiamine ... [more ▼]

Several important cofactors are adenine nucleotides with a vitamin as the catalytic moiety. Here, we report the discovery of the first adenine nucleotide containing vitamin B1: adenosine thiamine triphosphate (AThTP, 1), or thiaminylated ATP. We discovered AThTP in Escherichia coli and found that it accumulates specifically in response to carbon starvation, thereby acting as a signal rather than a cofactor. We detected smaller amounts in yeast and in plant and animal tissues. [less ▲]

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See detailPig tissues express a catalytically inefficient 25-kDa thiamine triphosphatase: Insight in the catalytic mechanisms of this enzyme
Szyniarowski, Piotr; Lakaye, Bernard ULg; Czerniecki, Jan ULg et al

in Biochimica et Biophysica Acta - General Subjects (2005), 1725(1), 93-102

Thiamine triphosphate (ThTP) is found in most organisms and may be an intracellular signal molecule produced in response to stress. We have recently cloned the cDNA coding for a highly specific mammalian ... [more ▼]

Thiamine triphosphate (ThTP) is found in most organisms and may be an intracellular signal molecule produced in response to stress. We have recently cloned the cDNA coding for a highly specific mammalian 25-kDa thiamine triphosphatase. The enzyme was active in all mammalian species studied except pig, although the corresponding mRNA was present. In order to determine whether the very low ThTPase activity in pig tissues is due to the absence of the protein or to a lack of catalytic efficiency, we expressed human and pig ThTPase in E. coli as GST fusion proteins. The purified recombinant pig GST-ThTPase was found to be 2-3 orders of magnitude less active than human GST-ThTPase. Using site-directed mutagenesis, we show that, in particular, the change of Glu85 to lysine is responsible for decreased solubility and catalytic activity of the pig enzyme. Immunohistochemical studies revealed a distribution of the protein in pig brain very similar to the one reported in rodent brain. Thus, our results suggest that a 25-kDa protein homologous to hThTPase but practically devoid of enzyme activity is expressed in pig tissues. This raises the possibility that this protein may play a physiological role other than ThTP hydrolysis. [less ▲]

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