INSTITUTO DE BIOTECNOLOGIA Y BIOLOGIA MOLECULAR
Unidad Ejecutora - UE
congresos y reuniones científicas
FliL roles on the two sets of Bradyrhizobium diazoefficiens flagellar systems
QUELAS, JUAN IGNACIO; MENGUCCI, FLORENCIA
Congreso; The 23th Annual Flagella Meeting; 2018
Bradyrhizobium diazoefficiens is a motile soil α-proteobacterium used as commercial inoculants for soybean crops due to its capability to fix atmospheric nitrogen. This species has two different flagellar systems composed of different sets of proteins that contribute to swimming motility: a subpolar system (with FliC flagellins) constitutively expressed and an inducible lateral system (with LafA flagellins). The lateral system induction depends on the carbon source, viscosity and oxygen level.We focused our experiments in a little protein called FliL whose specific role remains unclear despite it has been studied in several bacterial species. It seems to be associated to the flagellar basal body and would contribute to the stability of the flagellar structure when torque increases. B. diazoefficiens USDA 110 have two putative fliL genes, each one related to the subpolar or lateral flagellar gene clusters (fliLsub and fliLlat). In order to study their roles, we obtained in-frame deletional mutants for each gene. We made microscope observations and evaluated flagellin production and swimming behavior in semi-solid media.In semi-solid medium, the swimming halo of fliLlat was smaller than the wild-type, even when the subpolar and lateral filaments were expressed normally. This difference was exacerbated in viscous medium. By contrast, fliLsub strain swim more than the wild-type in semi-solid media and this difference declines when the viscosity of the medium increased. Due to this contradictory phenotype, we next constructed lafA/fliLsub and fliC/fliLlat double mutants expressing only one flagellar system. So, we performed the same swimming experiments and concluded that both FliL proteins contributes equally to the function and structure of B. diazoefficiens flagella.