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

• Published in: PloS one Vol. 13; no. 7; p. e0199110
• Main Authors: Wang, Yi, Geng, Changan, Yuan, Xiaolong, Hua, Mei, Tian, Fenghua, Li, Changtian
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 18.07.2018; Public Library of Science (PLoS)
• Subjects: Acids; Acyl carrier protein; Amino Acid Sequence - genetics; Aspergillus nidulans; Aspergillus oryzae; Base Sequence; Benzofurans - metabolism; Biology; Biology and Life Sciences; Biosynthesis; Chemistry; Claisen cyclase; Computer and Information Sciences; Education; Engineering research; Forestry; Fungi; Gene expression; Genes; Genetic aspects; Genomes; Genomics; Laboratories; Lichens; Lichens - enzymology; Lichens - genetics; Metabolites; Methyltransferase; Nephromopsis; Parmeliaceae - enzymology; Parmeliaceae - genetics; Phylogeny; Physical Sciences; Physiological aspects; Polyketide synthase; Polyketide Synthases - genetics; Polyketides; Proteins; Sequence Analysis, DNA; Usnic acid; United States > US; China; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0199110

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.