Streptomyces virginiae PPDC Is a New Type of Phenylpyruvate Decarboxylase Composed of Two Subunits

ACS Chem Biol. 2017 Aug 18;12(8):2008-2014. doi: 10.1021/acschembio.7b00307. Epub 2017 Jul 18.

Abstract

Streptomyces virginiae phenylpyruvate decarboxylase (PPDC) has not been identified before. Two putative branched-chain α-keto acid dehydrogenase subunit genes bkdC and bkdD from S. virginiae are similar to halves of other PPDC coding sequences. We cloned and characterized them biochemically in this work. The two proteins formed a stable complex attested by pull-down assay, consistent with the finding that their soluble expression was obtained only when they were coexpressed in Escherichia coli. The subunits were redesignated as SvPPDCα and SvPPDCβ, because the SvPPDCα/β complex catalyzed the conversion of phenylpyruvate to phenylacetaldehyde, reflecting the nature of the enzyme. Moreover, mutations of conserved residues in either of the two subunits led to inactivation or decreased specific activity of the enzymatic reaction. All previously identified PPDCs are encoded by a single gene. Here, we identified a new type of PPDC that contains two subunits, which gives new insights into the PPDC family.

MeSH terms

  • Amino Acid Sequence
  • Carboxy-Lyases / chemistry
  • Carboxy-Lyases / genetics*
  • Carboxy-Lyases / metabolism*
  • Catalytic Domain / genetics*
  • Enzyme Activation / genetics
  • Escherichia coli / genetics
  • Gene Expression Regulation, Bacterial
  • Mutation
  • Phenylpyruvic Acids / metabolism
  • Plasmids / genetics
  • Plasmids / metabolism
  • Sequence Alignment
  • Streptomycetaceae / enzymology*
  • Streptomycetaceae / genetics*

Substances

  • Phenylpyruvic Acids
  • Carboxy-Lyases
  • phenylpyruvate decarboxylase
  • phenylpyruvic acid