The periplasmic binding protein NrtT affects xantham gum production and pathogenesis in Xanthomonas citri

In Xanthomonas citri, the bacterium that causes citrus canker, three ATP‐binding cassette (ABC) transporters are known to be dedicated to the uptake of sulfur compounds. In this work, using functional, biophysical and structural methods, we showed that NrtT, a periplasmic component of the ABC transporter NrtCB, is an alkanesulfonate‐binding protein and that the deletion of the nrtT gene affected xantham gum synthesis, adhesion and biofilm production, similarly to the phenotype obtained in the X. citri ssuA‐knockout strain, in which the alkanesulfonate‐binding protein SsuA is absent. Although NrtA and SsuA share similar ligands, the function of these proteins is not complementary. These results emphasize that organic‐sulfur sources are directly involved with bacterial infection in vivo and are needed for pathogenesis in X. citri.