Elucidating essential proteins in the translocation of exopolysaccharide I in Sinorhizobium meliloti

RIVERO MR; MEDEOT D; LIAUDAT JP; ROSSI F; FERRARI W; TOUZ MC; FISCHER S; JOFRE E

Mendoza

Congreso; SAIB 2012; 2012

A Wzy-dependent like pathway, which includes the participation of ExoPTQF proteins, has been suggested to be involved in the polymerization of exopolysaccharide I (EPS I) of . However, the final steps of this process are poorly understood. Recently, by cellular fractionation and immunoblot, our group has evidenced a PCP2a family protein, ExoP, located in the inner membrane and its pivotal role in EPS I synthesis has been established. Here, we show preliminary results about the role of ExoF in this process and its potential interactions with ExoP. By bioinformatics analysis, we identified ExoF as OMA family member located in the outer membrane. Furthermore, generation of nonpolar exoF mutant resulted in a nonproducing EPS I phenotype. Fluorescence microscopy analysis of cells expressing ExoF-mCherry- and eGFP-ExoP tagged proteins, revealed that these proteins are highly dynamics during the exponential phase of growth. However, when the growth rate decreases, both proteins localize at cell poles and this moment is coincident with the beginning of EPS I export. Based on all these data, we postulate that ExoP and ExoF interact with each other to form a protein complex that allows the assemblage and translocation of EPS I. Shedding light in these mechanisms will increase our knowledge about biopolymers synthesis and export in this bacterium of agronomic and pecuary importance.