Sinorhizobium meliloti Fur-Like (Mur) Protein Binds a Fur Box-Like Sequence Present in the mntA Promoter in a Manganese-Responsive Manner

摘要

In Sinorhizobium meliloti, the MurSm protein, a homologue of the ferric uptake regulator (Fur), mediates manganese-dependent regulation of the MntABCD manganese uptake system. In this study, we analyzed MurSm binding to the promoter region of the S. meliloti mntA gene. We demonstrated that MurSm protein binds with high affinity to the promoter region of mntA gene in a manganese-responsive manner. Moreover, the results presented here indicate that two monomers, or one dimer, of MurSm binds the DNA. The binding region was identified by DNase I footprinting analysis and covers a region of about 30 bp long that contains a palindromic sequence. The MurSm binding site, present in the mntA promoter region, is similar to a Fur box; however, manganese-activated MurSm binds a canonical Fur box with very low affinity. Furthermore, the data obtained indicate that MurSm responds to physiological concentrations of manganese.