Identification and characterization of RibN, a novel family of riboflavin transporters from Rhizobium leguminosarum and other Proteobacteria

BONOMI HR; GARCÍA-ANGULO VA; POSADAS DM; SERER I; TORRES AG; ZORREGUIETA A; GOLDBAUM FA

Ciudad Autónoma de Buenos Aires

Congreso; Molecular mechanisms in cell signaling and gene expression; 2013

Fundación Instituto Leloir

Riboflavin (vitamin B2) is the precursor of FMN and FAD, which are essential cofactors for all living cells. Bacteria obtain riboflavin through endogenous biosynthesis or by the activity of transporter proteins able to import riboflavin from outside the cell. Often, these two functions coexist in the same species. To date, two families of bacterial riboflavin transporters have been experimentally characterized, YpaA/RibU and PnuX/RibM, whose orthologues are distributed among Gram-positive bacteria. In this work we identify and characterize a novel riboflavin transporter (RibN) from Rhizobium leguminosarum. Moreover, we demonstrate that RibN is required for a normal interaction of R. leguminosarum with its host plant. This work provides the first experimental evidence for (i) riboflavin transport in Gram-negative bacteria and (ii) the participation of a flavin transporter in the infectivity process. Finally, the study of other RibN homologs suggests that they may constitute a new family of riboflavin transporters in Proteobacteria.