Publications

• Studies in valine biosynthesis. V. Characteristics of the purified dihydroxyacid dehydratase from spinach leaves.

  KANAMORI M., WIXOM R.L.

  J Biol Chem 238:998-1005(1963) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• The active site of the Mycobacterium tuberculosis branched-chain amino acid biosynthesis enzyme dihydroxyacid dehydratase contains a 2Fe-2S cluster.

  Bashiri G., Grove T.L., Hegde S.S., Lagautriere T., Gerfen G.J., Almo S.C., Squire C.J., Blanchard J.S., Baker E.N.

  Iron-sulfur clusters are protein cofactors with an ancient evolutionary origin. These clusters are best known for their roles in redox proteins such as ferredoxins, but some iron-sulfur clusters have nonredox roles in the active sites of enzymes. Such clusters are often prone to oxidative degradat ... >> More

  Iron-sulfur clusters are protein cofactors with an ancient evolutionary origin. These clusters are best known for their roles in redox proteins such as ferredoxins, but some iron-sulfur clusters have nonredox roles in the active sites of enzymes. Such clusters are often prone to oxidative degradation, making the enzymes difficult to characterize. Here we report a structural and functional characterization of dihydroxyacid dehydratase (DHAD) from <i>Mycobacterium tuberculosis</i> (<i>Mtb</i>), an essential enzyme in the biosynthesis of branched-chain amino acids. Conducting this analysis under fully anaerobic conditions, we solved the DHAD crystal structure, at 1.88 Å resolution, revealing a 2Fe-2S cluster in which one iron ligand is a potentially exchangeable water molecule or hydroxide. UV and EPR spectroscopy both suggested that the substrate binds directly to the cluster or very close to it. Kinetic analysis implicated two ionizable groups in the catalytic mechanism, which we postulate to be Ser-491 and the iron-bound water/hydroxide. Site-directed mutagenesis showed that Ser-491 is essential for activity, and substrate docking indicated that this residue is perfectly placed for proton abstraction. We found that a bound Mg²⁺ ion 6.5 Å from the 2Fe-2S cluster plays a key role in substrate binding. We also identified a putative entry channel that enables access to the cluster and show that <i>Mtb</i>-DHAD is inhibited by a recently discovered herbicide, aspterric acid, that, given the essentiality of DHAD for <i>Mtb</i> survival, is a potential lead compound for the design of novel anti-TB drugs. << Less

  J. Biol. Chem. 294:13158-13170(2019) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• A reverse-phase high-performance liquid chromatography assay for dihydroxy-acid dehydratase.

  Smyk-Randall E.M., Brown O.R.

  A sensitive method for assaying dihydroxy-acid dehydratase activity is described. This enzyme produces alpha-ketoisovaleric and alpha-keto-beta-methylvaleric acids, respectively, in the biosynthesis of valine and isoleucine. These alpha-keto acids, after derivatization with 2,4-dinitrophenyl-hydra ... >> More

  A sensitive method for assaying dihydroxy-acid dehydratase activity is described. This enzyme produces alpha-ketoisovaleric and alpha-keto-beta-methylvaleric acids, respectively, in the biosynthesis of valine and isoleucine. These alpha-keto acids, after derivatization with 2,4-dinitrophenyl-hydrazine, were separated and quantified by reverse-phase high-performance liquid chromatography on a Zorbax octadecylsilane C-18 column. As little as 50 pmol of alpha-ketoisovaleric was detected in assays using cell-free extracts from Escherichia coli, whose measured specific activity was 8 mumol of alpha-ketoisovaleric acid produced per hour per milligram protein. << Less

  Anal Biochem 164:434-438(1987) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Dihydroxy acid dehydrase: an enzyme involved in the biosynthesis of isoleucine and valine.

  Myers J.W.

  J. Biol. Chem. 236:1414-1418(1961) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.