Regulación de la síntesis del flagelo subpolar en B. diazoefficiens

MENGUCCI FLORENCIA; ALTHABEGOITI, JULIA; DARDIS CAROLINA; LODEIRO, ANIBAL

Córdoba

Congreso; LII Reunión de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2016

SAIB

Bradyrhizobium diazoefficiens is the soybean nitrogen-fixing symbiont commonly used in inoculant formulations. This α-proteobacterium uses two independent flagellar systems to swim in liquid and viscous media. In our laboratory, we studied the synthesis and regulation of both flagellar systems, and here we show part of the regulatory cascade of the subpolar flagellum synthesis. Flagellar synthesis occurs in steps, each one controlled by different regulators. This process ensures the appropriate timing of the synthesis of different components. First, a master regulator initiates the signal cascade, then class II regulators control gene expression of the intermediate products and class III/IV regulators activate flagellum filament formation, the last product assembled. We present the characterization of B. diazoefficiens mutants in two class II regulatory genes (flbD and fliX) and two class III regulatory genes (flaF and flbT), by measuring the transcription levels of the putative targets controlled by them and also the type of flagellins that they produced. Our results suggest that the regulation of the subpolar flagellum synthesis is independent from the lateral flagella and is controlled in a cell-cycle manner. These results fit with the model previously described in Caulobacter crescentus but not with Salmonella model, as was thought in earlier studies