Molecular annotation of ketol-acid reductoisomerases from Streptomyces reveals a novel amino acid biosynthesis interlock mediated by enzyme promiscuity.

ABSTRACT: The 6-phosphogluconate dehydrogenase superfamily oxidize and reduce a wide range of substrates, making their functional annotation challenging. Ketol-acid reductoisomerase (KARI), encoded by the ilvC gene in branched-chain amino acids biosynthesis, is a promiscuous reductase enzyme within this superfamily. Here, we obtain steady-state enzyme kinetic parameters for 10 IlvC homologues from the genera Streptomyces and Corynebacterium, upon eight selected chemically diverse substrates, including some not normally recognized by enzymes of this superfamily. This biochemical data suggested a Streptomyces biosynthetic interlock between proline and the branched-chain amino acids, mediated by enzyme substrate promiscuity, which was confirmed via mutagenesis and complementation analyses of the proC,

SUBMITTER: Verdel-Aranda K 

PROVIDER: S-EPMC4353338 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature