PhpA, a tyrosine phosphatase of Myxococcus xanthus, is involved in the production of exopolysaccharide

Abstract

Protein-tyrosine phosphorylation plays a significant role in multiple cellular functions in bacteria. Bacterial tyrosine phosphatases catalyse the dephosphorylation of tyrosyl-phosphorylated proteins. Myxococcus xanthus PhpA shares homology with DNA polymerase and histidinol phosphatase family members. Recombinant His-tagged PhpA requires Mn 2+ or Co 2+ for phosphatase activity, and shows strict specificity for phosphorylated tyrosine residues. The k m values of PhpA for p-nitrophenyl phosphate (pNPP) and phosphotyrosine peptide, RRLIEDAEpYAARG, were 803 and 139 mM, respectively. The phosphatase activity of PhpA was inhibited by sodium orthovanadate with a k i of 33 mM. phpA gene expression was observed under both vegetative and developmental conditions, but peaked during late fruiting body formation. A phpA mutant exhibited an elevated level of tyrosine phosphorylation of a 79 kDa protein and cytoplasmic tyrosine kinase, BtkA. In M. xanthus, exopolysaccharide (EPS) is essential for cellcell adhesion and fruiting body formation. phpA mutant cells exhibited enhanced capacity for cellcell agglutination in agglutination buffer. Under starvation conditions, phpA mutation caused early aggregation and sporulation. The EPS production assay showed that the phpA mutant produced an increased amount of EPS in comparison with the wild-type. These results indicate that PhpA may negatively regulate the production of EPS in M. xanthus.

A Genetic Screen in Myxococcus xanthus Identifies Mutants That Uncouple Outer Membrane Exchange from a Downstream Cellular Response

“…S1C to D in the supplemental material). In support of these findings, Kimura and colleagues reported that a ⌬phpA mutant has a hyperagglutination phenotype (21).…”

“…The PhpA protein has been biochemically shown to function as a tyrosine phosphatase and, in a physiological context, is involved in exopolysaccharide (EPS) regulation, because a phpA mutant overexpresses EPS (21). Because EPS is required for S-motility (22), we tested the ⌬phpA mutant for S-motility defects in a strain that lacks A-motility (A Ϫ ).…”

Tyrosine Phosphorylation and Dephosphorylation in Burkholderia cenocepacia Affect Biofilm Formation, Growth under Nutritional Deprivation, and Pathogenicity

“…6B, D, and F). The calculated K m and V max values for BceD His (0.52 Ϯ 0.19 mM and 5.9 Ϯ 0.66 mol min Ϫ1 mg Ϫ1 , respectively), BCAM0208 His (0.27 Ϯ 0.08 mM and 6.7 Ϯ 0.6466 mol min Ϫ1 mg Ϫ1 , respectively) and BCAL2200 His (0.43 Ϯ 0.15 mM and 8.5 Ϯ 0.7666 mol min Ϫ1 mg Ϫ1 , respectively) were similar for all three enzymes and also within the range reported for other prokaryotic phosphatases (63)(64)(65).…”

“…Remarkably, BCAM0208, BceD, and BCAL2200 display similar kinetic parameters in vitro, as was also found with other bacterial tyrosine phosphatases (63)(64)(65). However, only BCAL2200 was required for the optimal growth of B. cenocepacia in minimal medium, suggesting that its function is particularly important for adaptation to nutrient starvation.…”

Sinorhizobium meliloti low molecular mass phosphotyrosine phosphatase SMc02309 modifies activity of the UDP-glucose pyrophosphorylase ExoN involved in succinoglycan biosynthesis

“…Furthermore, biochemical analyses demonstrated that SMc02309 is able to hydrolyse the artificial substrate p-NPP, a commonly used substrate in phosphatase assays in vitro (Bennett et al, 2001;Mori et al, 2012;Standish & Morona, 2014 obtained for SMc02309 were similar to those described for the LMW-PTP BceD of Burkholderia cepacia (Ferreira et al, 2007), the Wzb of Acinetobacter iwoffii (Nakar & Gutnick 2003), the Yor5 of Klebsiella pneumoniae (Preneta et al, 2002), the Wzb of E. coli (Vincent et al, 1999) and the Ptp of Acinetobacter johnsonii (Grangeasse et al, 1998). In addition, the optimal pH and temperature for catalytic activity resemble those for the above-mentioned bacterial Cysbased protein phosphatases.…”