Burkholderia pseudomallei, the causative agent of melioidosis, relies on iron acquisition for virulence, yet these systems remain poorly characterized beyond the malleobactin siderophore pathway. This study genetically characterizes the iron-responsive sigma factor MbaS. Using plasmid-based screening systems, we identified an upstream ATG codon and promoter region containing a Fur binding site essential for iron-responsive expression. Minimal MbaS-responsive promoter elements for mbaJ and mbaE were defined, and the MbaS DNA-binding site in mbaJ was mapped. Homology and mutagenesis studies confirmed domains for RNA polymerase and -10 sequence recognition. Results in E. coli mirrored B. pseudomallei, advancing understanding of iron-regulated gene expression.
