Current Genetics

, Volume 56, Issue 2, pp 151–162

Identification of a hybrid PKS–NRPS required for the biosynthesis of NG-391 in Metarhizium robertsii

  • Bruno Giuliano Garisto Donzelli
  • Stuart B. Krasnoff
  • Alice C. L. Churchill
  • John D. Vandenberg
  • Donna M. Gibson
Research Article

DOI: 10.1007/s00294-010-0288-0

Cite this article as:
Donzelli, B.G.G., Krasnoff, S.B., Churchill, A.C.L. et al. Curr Genet (2010) 56: 151. doi:10.1007/s00294-010-0288-0

Abstract

The fungal entomopathogen Metarhizium robertsii (formerly known as M. anisopliae var. anisopliae) is a prolific producer of secondary metabolites of which very little is known at the genetic level. To establish the genetic bases for the biosynthesis of the mutagenic compound NG-391, we identified a 19,818 kb genomic region harboring the predicted hybrid polyketide synthase-nonribosomal peptide synthetase NGS1, plus five additional ORFs. NGS1 knockouts generated by Agrobacterium-mediated transformation failed to produce detectable levels of NG-391, indicating the involvement of this locus in its biosynthesis. NGS1 deletion mutants had no significant changes in virulence levels against larvae of Spodoptera exigua and in resistance to hydrogen peroxide-generated oxidative stress compared to the wild-type strain. All 6 ORFs were expressed in medium supporting production of NG-391, and NGS1 was expressed during the interaction with the S. exigua host. The use of an NGS1 promoter–GFP reporter fusion showed that during in vitro growth in still broth cultures, NGS1 expression is restricted to the early exponential phase and is affected by M. robertsii cell density.

Keywords

Metarhizium robertsiiPKS–NRPSSecondary metabolismNG-391GFP reporter

Copyright information

© US Government 2010

Authors and Affiliations

  • Bruno Giuliano Garisto Donzelli
    • 1
  • Stuart B. Krasnoff
    • 1
  • Alice C. L. Churchill
    • 2
  • John D. Vandenberg
    • 1
  • Donna M. Gibson
    • 1
  1. 1.Biological Integrated Pest Management Research Unit, Robert W. Holley Center for Agriculture and Health USDA-ARSIthacaUSA
  2. 2.Department of Plant Pathology and Plant-Microbe BiologyCornell UniversityIthacaUSA