Twin Arginine Translocation in Mesorhizobium loti: Role in symbiotic process with Lotus sp

BASILE LA; LEPEK VC

Mar del Plata

Congreso; LI Reunión Anual SAIB; 2015

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

In rhizobia-legumes symbiosis atmospheric nitrogen is fixed in a process known as biological nitrogen fixation. This process is performed in specialized structures in legume roots and is fundamental for sustainable agricultural practices. Nodule formation is characterized by a complex exchange of signals between the plant and rhizobia; bacterial secretion systems are responsible for protein secretion to the media or to the host cell during the interaction. In this work we proposed to analyze the role of twin-arginine-translocation (TAT) system of Mesorhizobium loti in the symbiosis with Lotus sp. We have constructed mutants of M. loti deficient in tatC gene (one of the translocases in TAT system). By SDS-PAGE analysis we have observed a major number of proteins in ∆tatC culture supernants, which could be related to a defect on cell membranes, as seen in SDS sensibility assays. Lotus tenuis plants inoculated with tatC mutant produced a major but smaller and colorless number of nodules in roots, and plants presented a little but significant difference in dry weight and height. These results suggest that TAT system is not essential (as in other rhizobia) but has an effect in symbiosis. In silico analysis using TatFIND and PredTAT programs identified a list of possible candidates to be secreted by TAT; some interest proteins are being analyzed for further characterization of this system.