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The crystal structure of the enzyme 3-isopropylmalate dehydrogenase (IPMDH) from Mycobacterium tuberculosis (LeuB, Mtb-IPMDH, Rv2995c) without substrate or co-factor was determined at 1.65 A resolution, which is the highest resolution reported for an IPMDH to date. The crystals contain two functional dimers in the asymmetric unit in an arrangement close to a tetramer of D2 symmetry. Despite the absence of a substrate or inhibitor bound to the protein, the structure of the monomer resembles the previously observed closed form of the enzyme more closely than the open form. A comparison with the substrate complex of IPMDH from Thiobacillus ferrooxidans and the co-factor complex of the Thermus thermophilus enzyme revealed a close relationship of the active-site architecture between the various bacterial enzymes. The inhibitor O-isobutenyl oxalylhydroxamate was found to bind to the active site of IPMDH in a mode similar to the substrate isopropylmalate.

The high-resolution Structure of LeuB (Rv2995c) from Mycobacterium tuberculosis., Singh RK, Kefala G, Janowski R, Mueller-Dieckmann C, von Kries JP, Weiss MS, J Mol Biol. 2005 Feb 11;346(1):1-11. Epub 2004 Dec 23. PMID:15663922

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

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Categories: 3-isopropylmalate dehydrogenase | Mycobacterium tuberculosis | Janowski, R. | Kefala, G. | Mueller-Dieckmann, C. | Singh, R K. | TBSGC, TB Structural Genomics Consortium. | Weiss, M S. | Dehydrogenase,oxidoreductase,leucine biosynthesis,nad | Structural genomics,psi,protein structure initiative | Tb structural genomics consortium,tb | Tbsgc