Isolation of a novel cutinase homolog with polyethylene terephthalate-degrading activity from leaf-branch compost by using a metagenomic approach

Appl Environ Microbiol. 2012 Mar;78(5):1556-62. doi: 10.1128/AEM.06725-11. Epub 2011 Dec 22.

Abstract

The gene encoding a cutinase homolog, LC-cutinase, was cloned from a fosmid library of a leaf-branch compost metagenome by functional screening using tributyrin agar plates. LC-cutinase shows the highest amino acid sequence identity of 59.7% to Thermomonospora curvata lipase. It also shows the 57.4% identity to Thermobifida fusca cutinase. When LC-cutinase without a putative signal peptide was secreted to the periplasm of Escherichia coli cells with the assistance of the pelB leader sequence, more than 50% of the recombinant protein, termed LC-cutinase*, was excreted into the extracellular medium. It was purified and characterized. LC-cutinase* hydrolyzed various fatty acid monoesters with acyl chain lengths of 2 to 18, with a preference for short-chain substrates (C(4) substrate at most) most optimally at pH 8.5 and 50°C, but could not hydrolyze olive oil. It lost activity with half-lives of 40 min at 70°C and 7 min at 80°C. LC-cutinase* had an ability to degrade poly(ε-caprolactone) and polyethylene terephthalate (PET). The specific PET-degrading activity of LC-cutinase* was determined to be 12 mg/h/mg of enzyme (2.7 mg/h/μkat of pNP-butyrate-degrading activity) at pH 8.0 and 50°C. This activity is higher than those of the bacterial and fungal cutinases reported thus far, suggesting that LC-cutinase* not only serves as a good model for understanding the molecular mechanism of PET-degrading enzyme but also is potentially applicable for surface modification and degradation of PET.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carboxylic Ester Hydrolases / chemistry
  • Carboxylic Ester Hydrolases / isolation & purification*
  • Carboxylic Ester Hydrolases / metabolism*
  • Enzyme Stability
  • Escherichia coli / genetics
  • Fatty Acids / metabolism
  • Gene Library
  • Hydrogen-Ion Concentration
  • Metagenome*
  • Molecular Sequence Data
  • Polyethylene Terephthalates / metabolism*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Soil Microbiology*
  • Soil*
  • Substrate Specificity
  • Temperature

Substances

  • Fatty Acids
  • Polyethylene Terephthalates
  • Recombinant Proteins
  • Soil
  • Carboxylic Ester Hydrolases
  • cutinase

Associated data

  • GENBANK/HQ704839