Mur regulates the gene encoding the manganese transporter MntH in Brucella abortus 2308.

MntH is the only high-affinity manganese transporter identified in Brucella. A previous study showed that MntH is required for the wild-type virulence of Brucella abortus 2308 in mice (Anderson ES, et al., Infect. Immun. 77:3466-3474, 2009) and indicated that the mntH gene is regulated in a manganese-responsive manner in this strain by a Mur homolog. In the study presented here, the transcriptional start site for mntH in B. abortus 2308 was determined by primer extension analysis. Specific interactions between Mur and the mntH promoter region were demonstrated in an electrophoretic mobility shift assay (EMSA), and a Mur binding site was identified in the -55 to -24 region of the mntH promoter by DNase I footprint analysis. The specificity of the interaction of Mur with the putative Mur box was further evaluated by EMSA employing oligonucleotides in which the consensus nucleotides in this region were substituted. These studies not only confirm a direct role for Mur in the Mn-responsive regulation of mntH expression in Brucella abortus 2308 but also identify the cis-acting elements upstream of mntH that are responsible for this regulation.