4qii

Publication Abstract from PubMed

1,4-Dihydroxy-2-naphthoyl coenzyme A (DHNA-CoA) synthase catalyzes an essential intramolecular Claisen condensation in menaquinone biosynthesis and is an important target for the development of new antibiotics. This enzyme in Mycobacterium tuberculosis is cofactor-free and is classified as a type II DHNA-CoA synthase, differing from type I enzymes, which rely on exogenous bicarbonate for catalysis. Its crystal structures in complex with product analogues have been determined at high resolution to reveal ligand-dependent structural changes, which include the ordering of a 27-residue active-site loop (amino acids 107-133) and the reorientation of the carboxy-terminal helix (amino acids 289-301) that forms part of the active site from the opposing subunit across the trimer-trimer interface. These structural changes result in closure of the active site to the bulk solution, which is likely to take place through an induced-fit mechanism, similar to that observed for type I DHNA-CoA synthases. These findings demonstrate that the ligand-dependent conformational changes are a conserved feature of all DHNA-CoA synthases, providing new insights into the catalytic mechanism of this essential tubercular enzyme.

Ligand-dependent active-site closure revealed in the crystal structure of Mycobacterium tuberculosis MenB complexed with product analogues.,Song H, Sung HP, Tse YS, Jiang M, Guo Z Acta Crystallogr D Biol Crystallogr. 2014 Nov;70(Pt 11):2959-69. doi:, 10.1107/S1399004714019440. Epub 2014 Oct 23. PMID:25372686^[1]

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