Identification of a putative polyketide synthase gene involved in usnic acid biosynthesis in the lichen Nephromopsis pallescens

PLoS One. 2018 Jul 18;13(7):e0199110. doi: 10.1371/journal.pone.0199110. eCollection 2018.

Abstract

Usnic acid is a unique polyketide produced by lichens. To characterize usnic acid biosynthesis, the transcriptome of the usnic-acid-producing lichen-forming fungus Nephromopsis pallescens was sequenced using Illumina NextSeq technology. Seven complete non-reducing polyketide synthase genes and nine highly-reducing polyketide synthase genes were obtained through transcriptome analysis. Gene expression results obtained by qPCR and usnic acid detection with LCMS-IT-TOF showed that Nppks7 is probably involved in usnic acid biosynthesis in N. pallescens. Nppks7 is a non-reducing polyketide synthase with a MeT domain that also possesses beta-ketoacyl-ACP synthase, acyl transferase, product template, acyl carrier protein, C-methyltransferase, and Claisen cyclase domains. Phylogenetic analysis shows that Nppks7and other polyketide synthases from lichens form a unique monophyletic clade. Taken together, our data indicate that Nppks7 is a novel PKS in N. pallescens that is likely involved in usnic acid biosynthesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence / genetics
  • Base Sequence
  • Benzofurans / metabolism*
  • Lichens / enzymology*
  • Lichens / genetics
  • Parmeliaceae / enzymology*
  • Parmeliaceae / genetics
  • Phylogeny
  • Polyketide Synthases / genetics*
  • Sequence Analysis, DNA

Substances

  • Benzofurans
  • usnic acid
  • Polyketide Synthases

Grants and funding

This work was supported by a grant from National Natural Science Foundation of China (31400488), by the Applied Basic Research Project of Yunnan Province Grant (2016FB055) and by the Yunnan Academy of Forestry Innovation Fund Project, Grant (QN2018-01).