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Abstract
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.