ABSTRACT
Three cDNA clones encoding δ-guaiene synthase, a sesquiterpene cyclase, were isolated from tissue
cultures of Aquilaria microcarpa, and data mining analysis of the orthologous genes suggested
that 10 and 9 amino acid residues of N- and C-terminal ends of the translated products of these
clones remained undefined. The recombinant enzyme proteins, to which the putative missing Nand
C-terminal amino acid sequences (MSSAKLGSAS and ALLRHAIEI, respectively) were ligated,
exhibited the catalytic activities of sesquiterpene biosynthesis. Among these three δ-guaiene synthases,
two isoforms were capable of liberating α-guaiene, δ-guaiene, β-elemene plus α-humulene
as a minor product, while remaining one isoenzyme generated α-, δ-guaiene and β-elemene but
not α-humulene. Although the enzyme protein solely lacking in the N-terminal 10 amino acid residues
was capable of synthesizing the sesquiterpenoids, the protein without 9 amino acids at Cterminal
did not exhibit the catalytic activity. These results suggest that two types of δ-guaiene
synthase; α-, δ-guaiene, β-elemene-producing type, and α-, δ-guaiene, β-elemene plus α-humulene-producing type; concomitantly occur in A. microcarpa cell cultures, and several amino acid residues
at C-terminal of the synthase protein are essential to exhibit the catalytic activities as the
sesquiterpene cyclase.
Share and Cite:
Kurosaki, F. , Hirohashi, S. , Katoh, T. , Taura, F. and Lee, J. (2015) Cloning and Characterization of δ-Guaiene Synthase Genes Encoding a Sesquiterpene Cyclase from Aquilaria microcarpa Cell Cultures.
American Journal of Plant Sciences,
6, 2603-2611. doi:
10.4236/ajps.2015.616263.