Development of a genetic system for combinatorial biosynthesis of lipopeptides in Streptomyces fradiae and heterologous expression of the A54145 biosynthesis gene cluster

Appl Environ Microbiol. 2010 Oct;76(20):6877-87. doi: 10.1128/AEM.01248-10. Epub 2010 Aug 27.

Abstract

A54145 factors are calcium-dependent lipopeptide antibiotics produced by Streptomyces fradiae NRRL 18160. A54145 is structurally related to the clinically important daptomycin, and as such may be a useful scaffold for the development of a novel lipopeptide antibiotic. We developed methods to genetically manipulate S. fradiae by deletion mutagenesis and conjugal transfer of plasmids from Escherichia coli. Cloning the complete pathway on a bacterial artificial chromosome (BAC) vector and the construction of ectopic trans-complementation with plasmids utilizing the φC31 or φBT1 site-specific integration system allowed manipulation of A54145 biosynthesis. The BAC clone pDA2002 was shown to harbor the complete A54145 biosynthesis gene cluster by heterologous expression in Streptomyces ambofaciens and Streptomyces roseosporus strains in yields of >100 mg/liter. S. fradiae mutants defective in LptI methyltransferase function were constructed, and they produced only A54145 factors containing glutamic acid (Glu₁₂), at the expense of factors containing 3-methyl-glutamic acid (3mGlu₁₂). This provided a practical route to produce high levels of pure Glu₁₂-containing lipopeptides. A suite of mutant strains and plasmids was created for combinatorial biosynthesis efforts focused on modifying the A54145 peptide backbone to generate a compound with daptomycin antibacterial activity and activity in Streptococcus pneumoniae pulmonary infections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / biosynthesis*
  • Biological Products / biosynthesis
  • Biological Products / genetics
  • Biosynthetic Pathways / genetics*
  • Chromosomes, Artificial, Bacterial
  • Conjugation, Genetic
  • Escherichia coli / genetics
  • Genetic Complementation Test
  • Genetic Engineering / methods
  • Genetic Vectors
  • Genetics, Microbial / methods
  • Lipoproteins / biosynthesis
  • Lipoproteins / genetics
  • Multigene Family*
  • Plasmids
  • Streptococcus pneumoniae / drug effects
  • Streptomyces / genetics*
  • Streptomyces / metabolism*

Substances

  • A54145
  • Anti-Bacterial Agents
  • Biological Products
  • Lipoproteins