SMC02309, a novel low molecular weight phosphotyrosine phosphatase from Sinorhizobium meliloti

MEDEOT, D; RIVERO, M.R; CENDOYA, E; FERRARI, W; ROSSI, F; CONTRERAS-MOREIRA, B; FISCHER, S; JOFRÉ, E

Mendoza

Congreso; XLVIII Reunión Anual de SAIB; 2012

SAIB

In Gram-negative bacteria tyrosine phosphorylation has been shown to play a role in polysaccharide production. The predicted protein product of open reading frame Smc02309 from Sinorhizobium meliloti 2011 possesses significant similarity with known low molecular weight protein tyrosine phosphatases (LMW-PTP). KM and Vmax parameters for SMc02309 towards p-nitrophenyl phosphate are similar to those of other biochemical characterized bacterial LMW-PTP. Using a combination of immunodetection, mass spectrometric analysis and bioinformatics approaches, it was shown that SMc02309 is a protein phosphatase. Moreover, preliminary results provide evidence that the phosphatase SMc02309 can utilize the protein tyrosine kinase ExoP as an endogenous substrate. Bioinformatics approaches also evidence that, in contrary that happen in other bacterial species, in the S. meliloti 2011 genome these both proteins present a unique location. Altogether, these results suggest the occurrence of a novel regulatory mechanism connected with protein phosphorylation on tyrosine in S. meliloti. The identification and functional characterization of this novel phosphotyrosine-protein phosphatase will increase our understanding of key aspects of polysaccharides biosynthesis not only in bacteria of agricultural significance but also in polysaccharides-producing proteobacteria with human and animal health relevance.