The Role of Arg13 in Protein Phosphatase M tPphA from Thermosynechococcus elongatus.

ABSTRACT: A highly conserved arginine residue is close to the catalytic center of PPM/PP2C-type protein phosphatases. Different crystal structures of PPM/PP2C homologues revealed that the guanidinium side chain of this arginine residue can adopt variable conformations and may bind ligands, suggesting an important role of this residue during catalysis. In this paper, we randomly mutated Arginine 13 of tPphA, a PPM/PP2C-type phosphatase from Thermosynechococcus elongatus, and obtained 18 different amino acid variants. The generated variants were tested towards p-nitrophenyl phosphate and various phosphopeptides. Towards p-nitrophenyl phosphate as substrate, twelve variants showed 3-7 times higher K(m) values than wild-type tPphA and four variants (R13D, R13F, R13L, and R13W) completely lost activity.

SUBMITTER: Su J 

PROVIDER: S-EPMC3375153 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature