| Function Uniprot |
A redox-sensitive transcriptional regulator. Maintains intracellular redox homeostasis by regulating catabolic metabolism and polyketide biosynthesis. Regulates expression of the redox buffer ergothioneine (ERG) in a carbon-source-dependent manner; loss of ERG or mycothiol (MSH, the other major redox buffer in this bacteria) leads to respiratory alterations and bioenergetic deficiencies that negatively impact virulence. In response to low external pH (like that found in host macrophage phagosomes) alters endogenous gene expression leading to acid resistance; MSH and WhiB3 are probably part of a regulatory circuit that mediates gene expression upon acid stress. Regulates pathogenic lipid synthesis, coordinating proprionate flux (and other host-derived fatty acid oxidation intermediates) into methyl-branched fatty acids (polyacyltrehalose, phthiocerol dimycocerosates, sulfolipids) and the storage lipid triacylglycerol, functioning as reductive sinK. During intracellular growth M.tuberculosis uses host fatty acids as an energy source, generating large quantities of proprionate and NADH/NADPH, which are toxic and highly reducing respectively. WhiB3 is thought to help dissipate proprionate and NADH/NADPH by switching to the in vivo carbon source and via lipid anabolism. Responds to NO and O(2). Regulates expression of genes encoding modular polyketide synthases such as pks2, pks3 and fbpA. The oxidized apo-form of WhiB3 binds DNA (with 2 intramolecular disulfide bonds); holo-WhiB3 (with the 4Fe-4S cluster) binds DNA considerably less well. Discriminates poorly between specific and non-specific DNA-binding. Plays a role in virulence and nutritional stress. In its apo-form can act as a protein disulfide reductase. |