Identification of a novel PSR as the substrate of an SR protein kinase in the true slime mold
Source: The Journal of Biochemistry, Volume 149, Number 3, 10 March 2011 , pp. 275-283(9)
Publisher: Oxford University Press
Abstract:Here, a novel cDNA encoding a serine/arginine (SR)-rich protein, designated PSR, was isolated from the true slime mold Physarum polycephalum and expressed in Escherichia coli. The deduced amino acid (aa) sequence reveals that PSR contains RS repeats at its C-terminus, similar to the conventional PSRPK substrate ASF/SF2. To study the novel protein, we generated a variety of mutant constructs by PCR and site-directed mutagenesis. Our analysis indicated that the purified recombinant PSR was phosphorylated by PSRPK in vitro and the SR-rich domain (amino acids 460469) in the PSR protein was required for phosphorylation. In addition, removal of the docking motif (amino acids 424450) from PSR significantly reduced the overall catalytic efficiency of the phosphorylation reaction. We also found that the conserved ATP-binding region 62LGWGHFSTVWLAIDEKNGGREVALK86 and the serine/threonine protein kinases active-site signature 184IIHTDLKPENVLL196 of PSRPK played a crucial role in substrate phosphorylation and Lys86 and Asp188 were crucial for PSRPK phosphorylation of PSR. These results suggest that PSR is a novel SR-related protein that is phosphorylated by PSRPK.
Document Type: Regular Paper
Affiliations: 1: Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024 and , College of Life Science, Shenzhen Key Laboratory of Microbial and Genetic Engineering, Shenzhen University, Shenzhen 518060, P.R. China, 2: College of Life Science, Shenzhen Key Laboratory of Microbial and Genetic Engineering, Shenzhen University, Shenzhen 518060, P.R. China,
Publication date: 10 March 2011