3auj

Publication Abstract from PubMed

Coenzyme B(12) dependent diol dehydratase undergoes mechanism-based inactivation by glycerol, accompanying the irreversible cleavage of the coenzyme Co-C bond. Bachovchin et al. [Biochemistry16, 1082-1092 (1977)] reported that glycerol bound in the G(S) conformation, in which the pro-S-CH(2) OH group is oriented to the hydrogen-abstracting site, primarily contributes to the inactivation reaction. To understand the mechanism of inactivation by glycerol, we analyzed the X-ray structure of diol dehydratase complexed with cyanocobalamin and glycerol. Glycerol is bound to the active site preferentially in the same conformation as that of (S)-1,2-propanediol, i.e. in the G(S) conformation, with its 3-OH group hydrogen bonded to Seralpha301, but not to nearby Glnalpha336. k(inact) of the Salpha301A, Qalpha336A and Salpha301A/Qalpha336A mutants with glycerol was much smaller than that of the wild-type enzyme. k(cat) /k(inact) showed that the Salpha301A and Qalpha336A mutants are substantially more resistant to glycerol inactivation than the wild-type enzyme, suggesting that Seralpha301 and Glnalpha336 are directly or indirectly involved in the inactivation. The degree of preference for (S)-1,2-propanediol decreased on these mutations. The substrate activities towards longer chain 1,2-diols significantly increased on the Salpha301A/Qalpha336A double mutation, probably because these amino acid substitutions yield more space for accommodating a longer alkyl group on C3 of 1,2-diols. Database Structural data are available in the Protein Data Bank under the accession number 3AUJ. Structured digital abstract * Diol dehydrase gamma subunit, Diol dehydrase beta subunit and Diol dehydrase alpha subunit physically interact by X-ray crystallography (View interaction).

Redesign of coenzyme B(12) dependent diol dehydratase to be resistant to the mechanism-based inactivation by glycerol and act on longer chain 1,2-diols.,Yamanishi M, Kinoshita K, Fukuoka M, Saito T, Tanokuchi A, Ikeda Y, Obayashi H, Mori K, Shibata N, Tobimatsu T, Toraya T FEBS J. 2012 Mar;279(5):793-804. doi: 10.1111/j.1742-4658.2012.08470.x. Epub 2012, Jan 30. PMID:22221669^[1]

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