The Methanocaldococcus jannaschii protein Mj0968 is not a P-type ATPase

Autor(en): Bramkamp, M
Gassel, M
Herkenhoff-Hesselmann, B
Bertrand, J
Altendorf, K 
Stichwörter: 2 `-O-trinitrophenyl nucleotide binding; ADENOSINE 5'-TRIPHOSPHATE; BINDING; Biochemistry & Molecular Biology; Biophysics; CALCIUM-PUMP; Cell Biology; CYTOPLASMIC LOOP; ESCHERICHIA-COLI; MEMBRANE H+-ATPASE; Methanocaldococcus jannaschii; METHANOCOCCUS-JANNASCHII; Mj0968; NUCLEOTIDES; p-nitrophenyl phosphate hydrolysis; P-type ATPase; phosphatase; phosphorylation; SARCOPLASMIC-RETICULUM; TRIPHOSPHATASE
Erscheinungsdatum: 2003
Herausgeber: WILEY
Volumen: 543
Ausgabe: 1-3
Startseite: 31
Seitenende: 36
The Methanocaldococcus jannaschii (formerly Methanococcus jannaschii) protein Mj0968 has been reported to represent a soluble P-type ATPase [Ogawa et al., FEBS Lett. 471 (2000) 99-102]. In this study, we report that the heterologously expressed Mj0968-His(10) protein exhibits high rates of phosphatase activity, whereas only very low ATPase activity was measured. Replacement of the aspartate residue in the DSAGT motif (D7A), which becomes phosphorylated during the reaction cycle of P-type ATPases, does not affect the V-max, but only the K-M of the reaction. Labeling studies with [gamma-P-32]ATP and [alpha-P-32]ATP revealed that the previously reported labeling experiments [Ogawa et al., 2000] do not necessarily show phosphorylation of Mj0968, but rather point to ATP binding. Binding studies with trinitrophenyl adenosine nucleotides showed low apparent K-d values for those molecules. These results provide evidence that the native function of Mj0968 seems to be that of a phosphatase, rather than that of an ATP-hydrolyzing enzyme. (C) 2003 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.
ISSN: 18733468
DOI: 10.1016/S0014-5793(03)00372-7

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