The cloning, characterization and functional analysis of a gene encoding an acetyl-CoA acetyltransferase involved in triterpene biosynthesis in Ganoderma lucidum

To better understand the functions of key genes involved in triterpene biosynthesis in Ganoderma lucidum, we cloned and characterized an acetyl coenzyme A acetyltransferase gene (AACT), designated Ganoderma lucidum AACT (Gl-aact). The open reading frame (ORF) of Gl-aact encoded a 417-amino acid polypeptide with a theoretical pI of 8.89. The Gl-AACT sequence was highly homologous to those of other fungal AACTs. Meanwhile, analysis of the Gl-aact expression profile revealed a positive correlation between Gl-aact transcript abundance and triterpene content changes during the development of G. lucidum. The treatment of mycelia with exogenous methyl jasmonate (MeJA) caused the accumulation of Gl-aact messenger RNA. Gl-aact over-expressing transformants were obtained by Agrobacterium tumefaciens-mediated transformation (ATMT), and triterpene production was observed to be increased when Gl-aact was over-expressed. Our results suggest that this enzyme may play an important role in triterpene biosynthesis. (C) 2012 The Mycological Society of Japan. Published by Elsevier B. V. All rights reserved.