Type II thioesterase ScoT, associated with Streptomyces coelicolor A3(2) modular polyketide synthase Cpk, hydrolyzes acyl residues and has a preference for propionate

Appl Environ Microbiol. 2009 Feb;75(4):887-96. doi: 10.1128/AEM.01371-08. Epub 2008 Dec 12.


Type II thioesterases (TE IIs) were shown to maintain the efficiency of polyketide synthases (PKSs) by removing acyl residues blocking extension modules. However, the substrate specificity and kinetic parameters of these enzymes differ, which may have significant consequences when they are included in engineered hybrid systems for the production of novel compounds. Here we show that thioesterase ScoT associated with polyketide synthase Cpk from Streptomyces coelicolor A3(2) is able to hydrolyze acetyl, propionyl, and butyryl residues, which is consistent with its editing function. This enzyme clearly prefers propionate, in contrast to the TE IIs tested previously, and this indicates that it may have a role in control of the starter unit. We also determined activities of ScoT mutants and concluded that this enzyme is an alpha/beta hydrolase with Ser90 and His224 in its active site.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetates / metabolism
  • Amino Acid Sequence
  • Bacterial Proteins / metabolism*
  • Butyrates / metabolism
  • Catalytic Domain
  • DNA Mutational Analysis
  • Fatty Acid Synthases / genetics
  • Fatty Acid Synthases / metabolism*
  • Hydrolases / genetics
  • Hydrolases / metabolism
  • Kinetics
  • Models, Molecular
  • Molecular Sequence Data
  • Polyketide Synthases / metabolism*
  • Propionates / metabolism*
  • Protein Structure, Tertiary
  • Sequence Alignment
  • Streptomyces coelicolor / enzymology*
  • Substrate Specificity
  • Thiolester Hydrolases / genetics
  • Thiolester Hydrolases / metabolism*


  • Acetates
  • Bacterial Proteins
  • Butyrates
  • Propionates
  • Polyketide Synthases
  • Fatty Acid Synthases
  • Hydrolases
  • Thiolester Hydrolases
  • thioesterase II