Reference : A specific inorganic triphosphatase from Nitrosomonas europaea: structure and catalyt...
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
http://hdl.handle.net/2268/97231
A specific inorganic triphosphatase from Nitrosomonas europaea: structure and catalytic mechanism
English
Delvaux, David mailto [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Biochimie et physiologie humaine et pathologique >]
Murty, Mamidana R.V.S [ > > ]
Gabelica, Valérie mailto [Université de Liège - ULg > Département de chimie (sciences) > GIGA-R : Laboratoire de spectrométrie de masse (L.S.M.) >]
Lakaye, Bernard mailto [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Biochimie et physiologie humaine et pathologique >]
Lunin, Vladimir V. [ > > ]
Skarina, Tatiana [ > > ]
Onopriyenko, Olena [ > > ]
Kohn, Grégory mailto [Université de Liège - ULg > > GIGA - Neurosciences >]
Wins, Pierre [ > > ]
De Pauw, Edwin mailto [Université de Liège - ULg > Département de chimie (sciences) > GIGA-R : Laboratoire de spectrométrie de masse (L.S.M.) >]
Bettendorff, Lucien mailto [Université de Liège - ULg > Département des sciences biomédicales et précliniques > Biochimie et physiologie humaine et pathologique >]
2011
Journal of Biological Chemistry
American Society for Biochemistry and Molecular Biology
286
34023-34035
Yes (verified by ORBi)
International
0021-9258
1083-351X
Baltimore
MD
[en] Enzymology ; Structure ; CYTH ; Triphosphatase ; Thiamine triphosphatase ; Polyphosphate
[en] 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.
Giga-Neurosciences ; Giga-Systems Biology and Chemical Biology ; Banting and Best Department of Medical Research, University of Toronto
Fonds de la Recherche Fondamentale Collective - FRFC
Researchers ; Professionals
http://hdl.handle.net/2268/97231
10.1074/jbc.M111.233585
http://reflexions.ulg.ac.be/Nitrosomonas

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