References of "Georlette, D"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailA nondetergent sulfobetaine prevents protein aggregation in microcalorimetric studies
Collins, T.; D'Amico, Salvino ULg; Georlette, D. et al

in Analytical Biochemistry (2006), 352(2), 299-301

Detailed reference viewed: 7 (2 ULg)
Full Text
Peer Reviewed
See detailAdenylation-dependent conformation and unfolding pathways of the NAD(+)-dependent DNA ligase from the thermophile Thermus scotoductus
Georlette, D.; Blaise, Vinciane ULg; Bouillenne, Fabrice ULg et al

in Biophysical Journal (2004), 86(2), 1089-1104

In the last few years, an increased attention has been focused on NAD(+)-dependent DNA ligases. This is mostly due to their potential use as antibiotic targets, because effective inhibition of these ... [more ▼]

In the last few years, an increased attention has been focused on NAD(+)-dependent DNA ligases. This is mostly due to their potential use as antibiotic targets, because effective inhibition of these essential enzymes would result in the death of the bacterium. However, development of an efficient drug requires that the conformational modifications involved in the catalysis of NAD(+)-dependent DNA ligases are understood. From this perspective, we have investigated the conformational changes occurring in the thermophilic Thermus scotoductus NAD(+)-DNA ligase upon adenylation, as well as the effect of cofactor binding on protein resistance to thermal and chemical (guanidine hydrochloride) denaturation. Our results indicate that cofactor binding induces conformational rearrangement within the active site and promotes a compaction of the enzyme. These data support an induced "open-closure" process upon adenylation, leading to the formation of the catalytically active enzyme that is able to bind DNA. These conformational changes are likely to be associated with the protein function, preventing the formation of nonproductive complexes between deadenylated ligases and DNA. In addition, enzyme adenylation significantly increases resistance of the protein to thermal denaturation and GdmCl-induced unfolding, establishing a thermodynamic link between ligand binding and increased conformational stability. Finally, chemical unfolding of deadenylated and adenylated enzyme is accompanied by accumulation of at least two equilibrium intermediates, the molten globule and premolten globule states. Maximal populations of these intermediates are shifted toward higher GdmCl concentrations in the case of the adenylated ligase. These data provide further insights into the properties of partially folded intermediates. [less ▲]

Detailed reference viewed: 18 (2 ULg)
Full Text
Peer Reviewed
See detailSome like it cold: biocatalysis at low temperatures
Georlette, D.; Blaise, Vinciane ULg; Collins, T. et al

in FEMS Microbiology Reviews (2004), 28(1), 25-42

In the last few years, increased attention has been focused on a class of organisms called psychrophiles. These organisms, hosts of permanently cold habitats, often display metabolic fluxes more or less ... [more ▼]

In the last few years, increased attention has been focused on a class of organisms called psychrophiles. These organisms, hosts of permanently cold habitats, often display metabolic fluxes more or less comparable to those exhibited by mesophilic organisms at moderate temperatures. Psychrophiles have evolved by producing, among other peculiarities, "cold-adapted" enzymes which have the properties to cope with the reduction of chemical reaction rates induced by low temperatures. Thermal compensation in these enzymes is reached, in most cases, through a high catalytic efficiency associated, however, with a low thermal stability. Thanks to recent advances provided by X-ray crystallography, structure modelling, protein engineering and biophysical studies, the adaptation strategies are beginning to be understood. The emerging picture suggests that psychrophilic enzymes are characterized by an improved flexibility of the structural components involved in the catalytic cycle, whereas other protein regions, if not implicated in catalysis, may be even more rigid than their mesophilic counterparts. Due to their attractive properties, i.e., a high specific activity and a low thermal stability, these enzymes constitute a tremendous potential for fundamental research and biotechnological applications. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 12 (0 ULg)
Full Text
Peer Reviewed
See detailCofactor binding modulates the conformational stabilities and unfolding patterns of NAD(+)-dependent DNA ligases from Escherichia coli and Thermus scotoductus
Georlette, D.; Blaise, Vinciane ULg; Dohmen, C. et al

in Journal of Biological Chemistry (2003), 278(50), 49945-49953

DNA ligases are important enzymes required for cellular processes such as DNA replication, recombination, and repair. NAD(+)-dependent DNA ligases are essentially restricted to eubacteria, thus ... [more ▼]

DNA ligases are important enzymes required for cellular processes such as DNA replication, recombination, and repair. NAD(+)-dependent DNA ligases are essentially restricted to eubacteria, thus constituting an attractive target in the development of novel antibiotics. Although such a project might involve the systematic testing of a vast number of chemical compounds, it can essentially gain from the preliminary deciphering of the conformational stability and structural perturbations associated with the formation of the catalytically active adenylated enzyme. We have, therefore, investigated the adenylation-induced conformational changes in the mesophilic Escherichia coli and thermophilic Thermus scotoductus NAD(+)-DNA ligases, and the resistance of these enzymes to thermal and chemical (guanidine hydrochloride) denaturation. Our results clearly demonstrate that anchoring of the cofactor induces a conformational rearrangement within the active site of both mesophilic and thermophilic enzymes accompanied by their partial compaction. Furthermore, the adenylation of enzymes increases their resistance to thermal and chemical denaturation, establishing a thermodynamic link between cofactor binding and conformational stability enhancement. Finally, guanidine hydrochloride-induced unfolding of NAD(+)-dependent DNA ligases is shown to be a complex process that involves accumulation of at least two equilibrium intermediates, the molten globule and its precursor. [less ▲]

Detailed reference viewed: 9 (2 ULg)
Full Text
Peer Reviewed
See detailStructural and functional adaptations to extreme temperatures in psychrophilic, mesophilic, and thermophilic DNA ligases
Georlette, D.; Damien, B.; Blaise, Vinciane ULg et al

in Journal of Biological Chemistry (2003), 278(39), 37015-37023

Psychrophiles, host of permanently cold habitats, display metabolic fluxes comparable to those exhibited by mesophilic organisms at moderate temperatures. These organisms have evolved by producing, among ... [more ▼]

Psychrophiles, host of permanently cold habitats, display metabolic fluxes comparable to those exhibited by mesophilic organisms at moderate temperatures. These organisms have evolved by producing, among other peculiarities, cold-active enzymes that have the properties to cope with the reduction of chemical reaction rates induced by low temperatures. The emerging picture suggests that these enzymes display a high catalytic efficiency at low temperatures through an improved flexibility of the structural components involved in the catalytic cycle, whereas other protein regions, if not implicated in catalysis, may be even more rigid than their mesophilic counterparts. In return, the increased flexibility leads to a decreased stability of psychrophilic enzymes. In order to gain further advances in the analysis of the activity/flexibility/stability concept, psychrophilic, mesophilic, and thermophilic DNA ligases have been compared by three-dimensional-modeling studies, as well as regards their activity, surface hydrophobicity, structural permeability, conformational stabilities, and irreversible thermal unfolding. These data show that the cold-adapted DNA ligase is characterized by an increased activity at low and moderate temperatures, an overall destabilization of the molecular edifice, especially at the active site, and a high conformational flexibility. The opposite trend is observed in the mesophilic and thermophilic counterparts, the latter being characterized by a reduced low temperature activity, high stability and reduced flexibility. These results strongly suggest a complex relationship between activity, flexibility and stability. In addition, they also indicate that in cold-adapted enzymes, the driving force for denaturation is a large entropy change. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Full Text
Peer Reviewed
See detailExpression, purification, crystallization and preliminary X-ray crystallographic studies of a psychrophilic cellulase from Pseudoalteromonas haloplanktis
Violot, S.; Haser, R.; Sonan, G. et al

in Acta Crystallographica Section D-Biological Crystallography (2003), 59(Part 7), 1256-1258

The Antarctic psychrophile Pseudoalteromonas haloplanktis produces a cold-active cellulase. To date, a three-dimensional structure of a psychrophilic cellulase has been lacking. Crystallographic studies ... [more ▼]

The Antarctic psychrophile Pseudoalteromonas haloplanktis produces a cold-active cellulase. To date, a three-dimensional structure of a psychrophilic cellulase has been lacking. Crystallographic studies of this cold-adapted enzyme have therefore been initiated in order to contribute to the understanding of the molecular basis of the cold adaptation and the high catalytic efficiency of the enzyme at low and moderate temperatures. The catalytic core domain of the psychrophilic cellulase CelG from P. haloplanktis has been expressed, purified and crystallized and a complete diffraction data set to 1.8 Angstrom has been collected. The space group was found to be P2(1)2(1)2(1), with unit-cell parameters a = 135.1, b = 78.4, c = 44.1 Angstrom. A molecular-replacement solution, using the structure of the mesophilic counterpart Cel5A from Erwinia chrysanthemi as a search model, has been found. [less ▲]

Detailed reference viewed: 23 (1 ULg)
Full Text
See detailMicrocalorimetry as applied to psychrophilic enzymes
D'Amico, Salvino ULg; Georlette, D.; Collins, T. et al

in Ladbury, J. E. (Ed.) Biocalorimetry 2: Application of Calorimetry in the Biological Sciences (2003)

Detailed reference viewed: 14 (1 ULg)
Full Text
Peer Reviewed
See detailMolecular basis of cold adaptation
D'Amico, Salvino ULg; Claverie, P.; Collins, T. et al

in Philosophical Transactions of the Royal Society of London Series B-Biological Sciences (2002), 357(1423), 917-924

Cold-adapted, or psychrophilic, organisms are able to thrive at low temperatures in permanently cold environments, which in fact characterize the greatest proportion of our planet. Psychrophiles include ... [more ▼]

Cold-adapted, or psychrophilic, organisms are able to thrive at low temperatures in permanently cold environments, which in fact characterize the greatest proportion of our planet. Psychrophiles include both prokaryotic and eukaryotic organisms and thus represent a significant proportion of the living world. These organisms produce cold-evolved enzymes that are partially able to cope with the reduction in chemical reaction rates induced by low temperatures. As a rule, cold-active enzymes display a high catalytic efficiency, associated however, with a low thermal stability. In most cases, the adaptation to cold is achieved through a reduction in the activation energy that possibly originates from an increased flexibility of either a selected area or of the overall protein structure. This enhanced plasticity seems in turn to be induced by the weak thermal stability of psychrophilic enzymes. The adaptation strategies are beginning to be understood thanks to recent advances in the elucidation of the molecular characteristics of cold-adapted enzymes derived from X-ray crystallography, protein engineering and biophysical methods. Psychrophilic organisms and their enzymes have, in recent years, increasingly attracted the attention of the scientific community due to their peculiar properties that render them particularly useful in investigating the possible relationship existing between stability, flexibility and specific activity and as valuable tools for biotechnological purposes. [less ▲]

Detailed reference viewed: 23 (2 ULg)
See detailLife in the cold: psychrophilic enzymes
Collins, T.; Claverie, P.; D'Amico, Salvino ULg et al

in Recent Res. Devl. Proteins vol. 1 (2002)

Detailed reference viewed: 29 (2 ULg)
Full Text
Peer Reviewed
See detailDid Psychrophilic Enzymes Really Win the Challenge?
Zecchinon, Laurent ULg; Claverie, P.; Collins, T. et al

in Extremophiles : Life Under Extreme Conditions (2001), 5(5), 313-21

Organisms living in permanently cold environments, which actually represent the greatest proportion of our planet, display at low temperatures metabolic fluxes comparable to those exhibited by mesophilic ... [more ▼]

Organisms living in permanently cold environments, which actually represent the greatest proportion of our planet, display at low temperatures metabolic fluxes comparable to those exhibited by mesophilic organisms at moderate temperatures. They produce cold-evolved enzymes partially able to cope with the reduction in chemical reaction rates and the increased viscosity of the medium induced by low temperatures. In most cases, the adaptation is achieved through a reduction in the activation energy, leading to a high catalytic efficiency, which possibly originates from an increased flexibility of either a selected area of or the overall protein structure. This enhanced plasticity seems in return to be responsible for the weak thermal stability of cold enzymes. These particular properties render cold enzymes particularly useful in investigating the possible relationships existing between stability, flexibility, and specific activity and make them potentially unrivaled for numerous biotechnological tasks. In most cases, however, the adaptation appears to be far from being fully achieved. [less ▲]

Detailed reference viewed: 22 (0 ULg)
See detailCold-adapted enzymes: an unachieved symphony
D'Amico, Salvino ULg; Claverie, P.; Collins, T. et al

in Storey, K. B.; Storey, J. M. (Eds.) Cell and Molecular Responses to Stress vol.2. Protein adaptations and signal transduction, (2001)

Detailed reference viewed: 36 (3 ULg)
See detailCold-adapted enzymes
Georlette, D.; Bentahir, M.; Claverie, P. et al

in Bulte, J.; DeCuyper, M. (Eds.) Focus on Biotechnology – Physics and Chemistry Basis for Biotechnology (2001)

Detailed reference viewed: 19 (2 ULg)
Full Text
Peer Reviewed
See detailBovine Herpesvirus Type 1 Glycoprotein H Is Essential for Penetration and Propagation in Cell Culture
Meyer, G.; Hanon, E.; Georlette, D. et al

in Journal of General Virology (The) (1998), 79((Pt 8)), 1983-7

Bovine herpesvirus type 1 (BHV-1) glycoprotein H (gH) is a structural component of the virion which forms a complex with glycoprotein gL. To study the role of BHV-1 gH in the virus infectious cycle, a gH ... [more ▼]

Bovine herpesvirus type 1 (BHV-1) glycoprotein H (gH) is a structural component of the virion which forms a complex with glycoprotein gL. To study the role of BHV-1 gH in the virus infectious cycle, a gH null mutant was constructed in which the gH coding sequences were deleted and replaced by the Escherichia coli lacZ cassette. The BHV-1 gH null mutant was propagated in trans-complementing MDBK cells, stably transfected with plasmid pMEP4 containing the BHV-1 gH gene under the control of the inducible mouse metallothionein promoter. Experiments with the BHV-1 gH null mutant showed that gH is essential in the infectious cycle of the virus and is specifically involved in virus entry and cell-to-cell spread. The lack of infectivity of virions devoid of gH is not due to a defect in attachment. Moreover, PEG-induced fusion of virions to target cells provides evidence that BHV-1 gH is required for virion penetration. [less ▲]

Detailed reference viewed: 12 (1 ULg)