Publications

• chy1, an Arabidopsis mutant with impaired beta-oxidation, is defective in a peroxisomal beta-hydroxyisobutyryl-CoA hydrolase.

  Zolman B.K., Monroe-Augustus M., Thompson B., Hawes J.W., Krukenberg K.A., Matsuda S.P., Bartel B.

  The Arabidopsis chy1 mutant is resistant to indole-3-butyric acid, a naturally occurring form of the plant hormone auxin. Because the mutant also has defects in peroxisomal beta-oxidation, this resistance presumably results from a reduced conversion of indole-3-butyric acid to indole-3-acetic acid ... >> More

  The Arabidopsis chy1 mutant is resistant to indole-3-butyric acid, a naturally occurring form of the plant hormone auxin. Because the mutant also has defects in peroxisomal beta-oxidation, this resistance presumably results from a reduced conversion of indole-3-butyric acid to indole-3-acetic acid. We have cloned CHY1, which appears to encode a peroxisomal protein 43% identical to a mammalian valine catabolic enzyme that hydrolyzes beta-hydroxyisobutyryl-CoA. We demonstrated that a human beta-hydroxyisobutyryl-CoA hydrolase functionally complements chy1 when redirected from the mitochondria to the peroxisomes. We expressed CHY1 as a glutathione S-transferase (GST) fusion protein and demonstrated that purified GST-CHY1 hydrolyzes beta-hydroxyisobutyryl-CoA. Mutagenesis studies showed that a glutamate that is catalytically essential in homologous enoyl-CoA hydratases was also essential in CHY1. Mutating a residue that is differentially conserved between hydrolases and hydratases established that this position is relevant to the catalytic distinction between the enzyme classes. It is likely that CHY1 acts in peroxisomal valine catabolism and that accumulation of a toxic intermediate, methacrylyl-CoA, causes the altered beta-oxidation phenotypes of the chy1 mutant. Our results support the hypothesis that the energy-intensive sequence unique to valine catabolism, where an intermediate CoA ester is hydrolyzed and a new CoA ester is formed two steps later, avoids methacrylyl-CoA accumulation. << Less

  J. Biol. Chem. 276:31037-31046(2001) [PubMed] [EuropePMC]

• Primary structure and tissue-specific expression of human beta-hydroxyisobutyryl-coenzyme A hydrolase.

  Hawes J.W., Jaskiewicz J., Shimomura Y., Huang B., Bunting J., Harper E.T., Harris R.A.

  beta-Hydroxyisobutyryl-CoA (HIBYL-CoA) hydrolase is responsible for the specific hydrolysis of HIBYL-CoA, a saline catabolite, as well as the hydrolysis of beta-hydroxypropionyl-CoA, an intermediate in a minor pathway of propionate metabolism. We have obtained the amino acid sequences of several t ... >> More

  beta-Hydroxyisobutyryl-CoA (HIBYL-CoA) hydrolase is responsible for the specific hydrolysis of HIBYL-CoA, a saline catabolite, as well as the hydrolysis of beta-hydroxypropionyl-CoA, an intermediate in a minor pathway of propionate metabolism. We have obtained the amino acid sequences of several tryptic peptides derived from purified rat liver HIBYL-CoA hydrolase, and the NH2-terminal peptize sequence was matched to the translated sequence of a human expressed sequence tag present in the data base of the IMAGE Consortium (Lawrence Livermore National Laboratory, Livermore, CA). The complete nucleotide sequence and the deduced amino acid sequence showed no similarity to the sequences of well known thioesterases but showed significant homology to the enoyl-CoA hydratase/isomerase enzyme family. The cDNA fragment corresponding to the mature (processed) protein was expressed in Escherichia coli. The purified recombinant enzyme displayed substrate specificity very similar to that of the rat enzyme and was specifically bound by polyclonal antibodies raised against purified rat liver HIBYL-CoA hydrolase. Northern and Western blot analyses with various human tissues indicated predominant expression in liver, heart, and kidney, with discrepancies occurring in the amounts of HIBYL-CoA hydrolase mRNA compared to stably expressed protein in several tissues. << Less

  J. Biol. Chem. 271:26430-26434(1996) [PubMed] [EuropePMC]

• Divergent function in the crotonase superfamily: an anhydride intermediate in the reaction catalyzed by 3-hydroxyisobutyryl-CoA hydrolase.

  Wong B.J., Gerlt J.A.

  3-Hydroxyisobutyryl-CoA hydrolase (HICH), a member of the enoyl-CoA (crotonase) superfamily, catalyzes the hydrolysis of 3-hydroxyisobutyryl-CoA to 3-hydroxyisobutyrate. Like other members of the superfamily, the sequence of HICH contains conserved sequences for an oxyanion hole that stabilizes an ... >> More

  3-Hydroxyisobutyryl-CoA hydrolase (HICH), a member of the enoyl-CoA (crotonase) superfamily, catalyzes the hydrolysis of 3-hydroxyisobutyryl-CoA to 3-hydroxyisobutyrate. Like other members of the superfamily, the sequence of HICH contains conserved sequences for an oxyanion hole that stabilizes anionic intermediates. In contrast to most members of the superfamily, the reaction catalyzed by HICH does not proceed via formation of a thioester enolate anion; instead, evidence based on substrate deuterium isotope effects, the reactivity of substrate analogues that cannot form thioester enolate anions, single-turnover experiments in H218O, and the kinetic phenotypes of site-directed mutants provide evidence for a mechanism involving the formation of an anhydride intermediate involving Glu143 in the active site. In the reactions catalyzed by many members of the superfamily, homologues of Glu143 abstract the alpha proton of the thioester substrate to generate the thioester enolate anion intermediate. Presumably, one or more of the anionic tetrahedral intermediates on the HICH reaction coordinate are stabilized by the oxyanion hole. Thus, we conclude that the conserved oxyanion hole in this superfamily can be used to stabilize a variety of anionic intermediates. << Less

  J Am Chem Soc 125:12076-12077(2003) [PubMed] [EuropePMC]

• The biochemistry of peroxisomal beta-oxidation in the yeast Saccharomyces cerevisiae.

  Hiltunen J.K., Mursula A.M., Rottensteiner H., Wierenga R.K., Kastaniotis A.J., Gurvitz A.

  Peroxisomal fatty acid degradation in the yeast Saccharomyces cerevisiae requires an array of beta-oxidation enzyme activities as well as a set of auxiliary activities to provide the beta-oxidation machinery with the proper substrates. The corresponding classical and auxiliary enzymes of beta-oxid ... >> More

  Peroxisomal fatty acid degradation in the yeast Saccharomyces cerevisiae requires an array of beta-oxidation enzyme activities as well as a set of auxiliary activities to provide the beta-oxidation machinery with the proper substrates. The corresponding classical and auxiliary enzymes of beta-oxidation have been completely characterized, many at the structural level with the identification of catalytic residues. Import of fatty acids from the growth medium involves passive diffusion in combination with an active, protein-mediated component that includes acyl-CoA ligases, illustrating the intimate linkage between fatty acid import and activation. The main factors involved in protein import into peroxisomes are also known, but only one peroxisomal metabolite transporter has been characterized in detail, Ant1p, which exchanges intraperoxisomal AMP with cytosolic ATP. The other known transporter is Pxa1p-Pxa2p, which bears similarity to the human adrenoleukodystrophy protein ALDP. The major players in the regulation of fatty acid-induced gene expression are Pip2p and Oaf1p, which unite to form a transcription factor that binds to oleate response elements in the promoter regions of genes encoding peroxisomal proteins. Adr1p, a transcription factor, binding upstream activating sequence 1, also regulates key genes involved in beta-oxidation. The development of new, postgenomic-era tools allows for the characterization of the entire transcriptome involved in beta-oxidation and will facilitate the identification of novel proteins as well as the characterization of protein families involved in this process. << Less

  FEMS Microbiol. Rev. 27:35-64(2003) [PubMed] [EuropePMC]

• Purification and partial characterization of 3-hydroxyisobutyryl-coenzyme A hydrolase of rat liver.

  Shimomura Y., Murakami T., Fujitsuka N., Nakai N., Sato Y., Sugiyama S., Shimomura N., Irwin J., Hawes J.W., Harris R.A.

  An unusual feature of valine catabolism is a reaction in which an intermediate of its catabolic pathway, (S)-3-hydroxyisobutyryl-CoA, is hydrolyzed to give the free acid and CoA-SH. The enzyme responsible for this reaction, 3-hydroxyisobutyryl-CoA hydrolase (EC 3.1.2.4), was purified 7200-fold fro ... >> More

  An unusual feature of valine catabolism is a reaction in which an intermediate of its catabolic pathway, (S)-3-hydroxyisobutyryl-CoA, is hydrolyzed to give the free acid and CoA-SH. The enzyme responsible for this reaction, 3-hydroxyisobutyryl-CoA hydrolase (EC 3.1.2.4), was purified 7200-fold from rat liver in this study. The purified enzyme consists of a single polypeptide with an M(r) of 36,000 in the native and denatured forms. The hydrolase is highly specific for (S)-3-hydroxyisobutyryl-CoA and 3-hydroxypropionyl-CoA (Km, 6 and 25 microM, respectively) with optimal activity around pH 8. The turnover rate of the enzyme for (S)-3-hydroxyisobutyryl-CoA is 270 s-1, which is high relative to other enzymes of the valine pathway. Likewise, activity of the enzyme expressed on a wet weight basis is also very high in the major tissues of the rat. These findings suggest that rapid destruction of (S)-3-hydroxyisobutyryl-CoA produced during valine catabolism is physiologically important. We propose that the need for a mechanism to protect cells against the toxic effects of methacrylyl-CoA, which is maintained in equilibrium with (S)-3-hydroxyisobutyryl-CoA by crotonase, explains why valine catabolism involves this enzyme and why its tissue activity is so high. << Less

  J. Biol. Chem. 269:14248-14253(1994) [PubMed] [EuropePMC]