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Publication Abstract from PubMed

Iron is an essential element for life, but its soluble form is scarce in the environment and is rarer in the human body. Mycobacterium tuberculosis (Mtb) produces two aryl-capped siderophores, mycobactin (MBT) and carboxymycobactin (cMBT), to chelate intracellular iron. The adenylating enzyme MbtA catalyzes the first step of mycobactin biosynthesis in two half-reactions: activation of the salicylic acid as an acyl-adenylate and ligation onto the acyl carrier protein (ACP) domain of MbtB to form covalently salicylated MbtB-ACP. We report the first apo-MbtA structure from Mycobacterium smegmatis at 2.3 A. We demonstrate here that MbtA activity can be reversibly, post-translationally regulated by acetylation. Indeed the mycobacterial protein acetyltransferase (Pat), Rv0998, specifically acetylates MbtA on lysine 546, in a cAMP-dependent manner, leading to enzyme inhibition. MbtA acetylation can be reversed by the NAD+-dependant deacetyltransferase, Rv1151c (DAc). Deletion of Pat and DAc genes in Mtb revealed distinct phenotypes for strains lacking one or the other genes at low pH and limiting iron conditions. This study establishes a direct connection between the reversible acetylation system Pat/DAc and the ability of Mtb to adapt in limited iron conditions, which is critical for mycobacterial infection.

Post-Translational Acetylation of MbtA Modulates Mycobacterial Siderophore Biosynthesis.,Vergnolle O, Xu H, Tufariello JM, Favrot L, Malek AA, Jacobs WR Jr, Blanchard JS J Biol Chem. 2016 Aug 26. pii: jbc.M116.744532. PMID:27566542^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.