INSTITUTO DE BIOTECNOLOGIA Y BIOLOGIA MOLECULAR
Unidad Ejecutora - UE
congresos y reuniones científicas
Systematic inactivation and phenotypic characterization of two-component signal transduction systems of Sinorhizobium meliloti
ALBICORO, F.; DRAGHI, W. O.; SALAS, M, E.; MARTINI, C; ALVAREZ, F.; TORRES TEJERIZO, G. A.; PISTORIO, M.; LAGARES, A.; BECKER, A.; DEL PAPA, M.F.
Workshop; II Workshop Latinoamericano de PGPR; 2014
Univ. Nac. de Rio IV - Univ. Nac. de Quilmes
Sinorhizobium meliloti is a gram-negative proteobacterium able to establish nitrogen-fixing symbiosis with legumes of the genera Medícogo, Melilotus, and Trígonella. This association is tightly regulated. Either in the process of infection of the plant host or in free-living stage, rhizobial strains must adapt and respond to different environmental stimuli, including those from the plant host. This leads us to investigate the role of two-component signal transduction in the regulation of S. meliloti physiology. The cellular roles of most two-component systems (TCS) and the genes they activate remain unknown. We used a bioinformatics approach to identify the two-component systems (TCS) of S. meliloti. The available S. meliloti genome and the followíng tools were used: Simple Modular Architecture Research Tool (SMART), Pfam programs, and BLAST. By bioinformatics analysis, we identified the TCS consisting of a 40 sensory histidine-kinases (HK), including 8 hybrid HKs and 60 response regulator. ln an effort to identify the potential function of each TCS in the biology of S. meliloti strain zOLl, we analyzed the consequences of the disruption of the RR. 5. melilotí zOLl response regulators (RR) mutants were obtained either by TnS transposon mutagenesis (Pobigaylo et al 2006) or constructed by single cross-over method, At the moment, we obtained a collection of 35 mutants, 22of them generated by In5 transposon mutagenesis and the other 13 were achieved by single cross-over method. By this method, we were not able to inactivate an ortholog of ctrA,this gene has beenpreviously shown to be one of the key genes involved in the viability of some gram-negative micioorganisms. The biological effects of the 35 mutations were assessed by biofilm formatíon and environmental stress. We identified TCS related to acid and osmotic environmental stress in S. meliloti. The characterization of the RR genes implicated in the response to stress, their regulatíon, hierarchical role and specificity is a valuable tool for the understanding of basic aspects in the symbiosis process. This approach could contribute to the rational and efficient biotechnological improvement of inoculant rhizobia.