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

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.
AuthorsDylan C Alexander, Jessica Rock, Xiaowei He, Paul Brian, Vivian Miao, Richard H Baltz
JournalApplied and environmental microbiology (Appl Environ Microbiol) Vol. 76 Issue 20 Pg. 6877-87 (Oct 2010) ISSN: 1098-5336 [Electronic] United States
PMID20802082 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • A54145
  • Anti-Bacterial Agents
  • Biological Products
  • Lipoproteins
  • Anti-Bacterial Agents (biosynthesis)
  • Biological Products (biosynthesis, 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, genetics)
  • Multigene Family
  • Plasmids
  • Streptococcus pneumoniae (drug effects)
  • Streptomyces (genetics, metabolism)

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