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Publication Abstract from PubMed

l-arginine is used as a source of both carbon and nitrogen in Mycobacterium tuberculosis (Mtb) and its biosynthesis is essential for the pathogen's survival. MtbArgA (Rv2747) catalyzes the initial step in l-arginine biosynthesis by transferring an acetyl group from acetyl coenzyme A (AcCoA) to l-glutamate. MtbArgA is a class III N-acetylglutamate synthase (NAGS) with no structural information. Here, we solved the crystal structure of MtbArgA complexed with AcCoA and l-glutamate. The overall structure adopts a classic fold of the GCN5-related N-acetyltransferase (GNAT) family, characterized by a "V"-shaped cleft and beta-bulge, but uses distinct residues for the binding and reaction of AcCoA. In particular, its activity depends on dimerization to form a deep, vast pocket for l-glutamate binding. Interestingly, in the structure, l-glutamate binds at a site far away from AcCoA, implying a mechanism of separate capture and catalysis. Additionally, based on a docking model of l-glutamate at the catalytic site, a one-step sequential mechanism was proposed for enzymatic catalysis. Important sites for substrate binding and catalysis were also evaluated by site-directed mutagenesis study and activity analysis. The unique features of the MtbArgA structure will provide useful insights for inhibitor design and anti-tuberculosis drug discovery.

Crystal structure of l-glutamate N-acetyltransferase ArgA from Mycobacterium tuberculosis.,Yang X, Wu L, Ran Y, Xu A, Zhang B, Yang X, Zhang R, Rao Z, Li J Biochim Biophys Acta. 2017 Sep 21. pii: S1570-9639(17)30225-X. doi:, 10.1016/j.bbapap.2017.09.009. PMID:28943401^[2]

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