8br4 | pdb_00008br4
Structure of GAPDH from Mycobacterium tuberculosis
Structural highlights
FunctionG3P_MYCTU Catalyzes the oxidative phosphorylation of glyceraldehyde 3-phosphate (G3P) to 1,3-bisphosphoglycerate (BPG) using the cofactor NAD. The first reaction step involves the formation of a hemiacetal intermediate between G3P and a cysteine residue, and this hemiacetal intermediate is then oxidized to a thioester, with concomitant reduction of NAD to NADH. The reduced NADH is then exchanged with the second NAD, and the thioester is attacked by a nucleophilic inorganic phosphate to produce BPG.[1] Publication Abstract from PubMedGlyceraldehyde-3-phosphate-dehydrogenase (GAPDH; EC1.2.1.12) has several functions in Mycobacterium tuberculosis (Mtb) and the human host. Apart from its role in glycolysis, it serves both as a cell surface and a secreted receptor for plasmin(ogen) (Plg/Plm), transferrin (Tf), and lactoferrin (Lf). Plg sequestration by Mtb GAPDH facilitates bacterial adhesion and tissue invasion, while an equivalent interaction with host GAPDH regulates immune cell migration. In both, host and microbe, internalization of Tf/Lf-GAPDH complexes serves as a route for iron acquisition. To date, the structure of Mtb GAPDH or the residues involved in these moonlighting interactions have not been identified. This study provides the first known X-ray crystal structure of Mtb GAPDH. Through further mutagenesis and functional assays, we found that the C-terminal lysines of Mtb and human GAPDH affect enzyme activity and ligand binding. We also establish the stoichiometry of Plg, Tf and Lf interactions with the GAPDH tetramer. Lastly, molecular simulation studies reveal the interactions of the C-terminal lysine residues. Stoichiometry of ligand binding and role of C-terminal lysines in Mycobacterium tuberculosis and human GAPDH multifunctionality.,Kumar A, Kumar R, Boradia VM, Malhotra H, Kumar A, Seth S, Garg P, Karthikeyan S, Raje M, Iyengar Raje C FEBS J. 2024 Oct 22. doi: 10.1111/febs.17298. PMID:39436721[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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