Premium
The Methanocaldococcus jannaschii protein Mj0968 is not a P‐type ATPase
Author(s) -
Bramkamp Marc,
Gaßel Michael,
Herkenhoff-Hesselmann Brigitte,
Bertrand Jessica,
Altendorf Karlheinz
Publication year - 2003
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(03)00372-7
Subject(s) - methanococcus , atpase , phosphatase , nucleotide , biochemistry , enzyme , biology , adenosine triphosphate , phosphorylation , p type atpase , chemistry , escherichia coli , gene
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 [γ‐ 32 P]ATP and [α‐ 32 P]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.