A combined approach of classical mutagenesis and rational metabolic engineering improves rapamycin biosynthesis and provides insights into methylmalonyl-CoA precursor supply pathway in Streptomyces hygroscopicus ATCC 29253

Won Seok Jung, Young Ji Yoo, Je Won Park, Sung Ryeol Park, Ah Reum Han, Yeon Hee Ban, Eun Ji Kim, Eunji Kim, Yeo Joon Yoon

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Rapamycin is a macrocyclic polyketide with immunosuppressive, antifungal, and anticancer activity produced by Streptomyces hygroscopicus ATCC 29253. Rapamycin production by a mutant strain (UV2-2) induced by ultraviolet mutagenesis was improved by approximately 3.2-fold (23.6 mg/l) compared to that of the wild-type strain. The comparative analyses of gene expression and intracellular acyl-CoA pools between wild-type and the UV2-2 strains revealed that the increased production of rapamycin in UV2-2 was due to the prolonged expression of rapamycin biosynthetic genes, but a depletion of intracellular methylmalonyl-CoA limited the rapamycin biosynthesis of the UV2-2 strain. Therefore, three different metabolic pathways involved in the biosynthesis of methylmalonyl-CoA were evaluated to identify the effective precursor supply pathway that can support the high production of rapamycin: propionyl-CoA carboxylase (PCC), methylmalonyl-CoA mutase, and methylmalonyl-CoA ligase. Among them, only the PCC pathway along with supplementation of propionate was found to be effective for an increase in intracellular pool of methylmalonyl-CoA and rapamycin titers in UV2-2 strain (42.8 mg/l), indicating that the PCC pathway is a major methylmalonyl-CoA supply pathway in the rapamycin producer. These results demonstrated that the combined approach involving traditional mutagenesis and metabolic engineering could be successfully applied to the diagnosis of yield-limiting factors and the enhanced production of industrially and clinically important polyketide compounds.

Original languageEnglish
Pages (from-to)1389-1397
Number of pages9
JournalApplied Microbiology and Biotechnology
Issue number5
Publication statusPublished - 2011 Sep 1



  • Metabolic engineering
  • Methylmalonyl-CoA
  • Propionyl-CoA carboxylase
  • Random mutagenesis
  • Rapamycin

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology

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