Pseudomonas ADAPTATION TO DIFFERENT ECOLOGICAL NICHES: PHOSPHORYLCHOLINE PHOSPHATASE APPROACH

OTERO, LH; OYOLA, M; KILMURRAY, C; BEASSONI, PR

Huerta Grande, Cordoba

Congreso; XVII Jornadas de la Sociedad de Biología de Córdoba; 2009

Sociedad de Biologia de Cordoba

On the basis of 16s RNA, Pseudomonas genus belongs to group I, in the γ-branch. This group includes mammal`s pathogens (ie. P. aeruginosa), plant`s pathogens (ie. P. syringae) and non-pathogens (ie P. fluorescens, P. putida. When P. aeruginosa grows in choline-cointaing media, sintethizes Phospholipase C (PlcH) and Phosphorylcholine phosphatase (PchP), two enzymes that had been involved in pathogenesis of this bacterium. The absence of PlcH in P. syringae, P. fluorescens y P. putida led us to focus in PchP properties. Motifs I and III of PchP are identical in the four species analyzed. But in motif II, PchP de P. aeruginosa y P. putida have a serine residue while P. fluoresecens and P. syringae have a threonine residue in the same position. All this enzymes have a KM value for p-NPP in the same range. Nevertheless, with Zn2+ and Mg2+  as cofactors, the affinity was similar, but with Cu2+ it was ≈ 2.5 times lower for PchP of P. syringae and P. fluorescens, and  ≈ 4 times lower in P. aeruginosa y P. putida. All the enzymes showed preference for these ions in the order Zn2+  > Cu2+ > Mg2+. On the other hand, in P. aeruginosa y P. putida, PchP showed a higer KA for the three cations respects of P. syringae y P. fluorescens enzymes. For this, the serine/threonine residue in motif II may be one of the factors involving the affinity of PchP for Zn2+ , Cu2+y Mg2+. This change seems to be an indicator of PchP function in bacteria colonizing different ecological niches