USE OF RECOMBINATION-BASED IN VIVO EXPRESSION TECHNOLOGY (RIVET) FOR THE IDENTIFICATION OF Sinorhizobium meliloti GENES INDUCED BY SUB-LETHAL CONCENTRATIONS OF HYDROGEN PEROXIDE

ESCANCIANO, D.; SALAS, M.E.; ALVAREZ, F.; LÓPEZ, J.L.; DRAGHI, W.O.; LAGARES, A.; LOZANO, M.J.

Córdoba

Congreso; XI Congreso Argentino de Microbiología General; 2015

SAMIGE

Sinorhizobium meliloti is a gram-negative proteobacterium able to establish nitrogen-fixing symbiosis with legumes of the generaMedicago, Melilotus, and Trigonella. This symbiotic interaction is a highly regulated process that involves a complex bidirectionalmolecular dialog which ends with the differentiation of the rhizobium into a nitrogen fixing bacteroid and the generation of a newplant organ, the nodule. Several of the signal molecules involved have been identified, and among them, a signal role for thehydrogen peroxide has been proposed. In this work we make use of a Recomination-basedin vivoexpression technology(RIVET) system modification created in our laboratory for the identification of genes induced during the growth of Sinorhizobiummeliloti in complex media supplemented with sub-lethal concentrations of hydrogen peroxide. Using this approach we were ableto identify that the cyaD1 gene, which shows a typical type III adenylate cyclase/guanylate cyclase (AC/GC) structuralorganization (namely, an amino-terminal signal peptide, a CHASE2 extracellular domain, a set of three membrane-spanningdomains, and a cytoplasmic catalytic domain), is differentially induced by hydrogen peroxide. This fact might indicate a possiblerole of the second messenger cAMP in the signaling path of hydrogen peroxide during the symbiotic interaction. Preliminaryresults obtained with a cyaD1 mini-Tn5 insertional mutant indicate also a possible role of this protein in hydrogen peroxidetolerance.