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...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.展开更多
Mevalonate pathway for isoprenoid biosynthesis was constructed in Escherichia coli cells by the transformation with a gene cluster isolated from Streptomyces sp., and farnesyl diphosphate synthase and δ-guaiene synth...Mevalonate pathway for isoprenoid biosynthesis was constructed in Escherichia coli cells by the transformation with a gene cluster isolated from Streptomyces sp., and farnesyl diphosphate synthase and δ-guaiene synthase genes were coexpressed in this strain. This transformant was capable of liberating an appreciable amount of δ-guaiene, an aroma sesquiterpene compound accumulated in agarwood, and its concentration was elevated to more than 30 μg/ml culture by the incubation with mevalonolactone as an isoprene precursor in a nutrient-enriched Terrific broth. Coexpression of type 1 isopentenyl diphosphate isomerase plus acetoacetyl-CoA ligase genes also enhanced δ-guaiene production, and the concentration of the compound was approximately 38 - 42 μg/ml culture in the presence of mevalonolactone or lithium acetoacetate. These results clearly indicate that mevalonate pathway-engineered E. coli cells showed an appreciable δ-guaiene producing activity in the en- riched medium in the presence of appropriate isoprene precursors.展开更多
文摘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.
文摘Mevalonate pathway for isoprenoid biosynthesis was constructed in Escherichia coli cells by the transformation with a gene cluster isolated from Streptomyces sp., and farnesyl diphosphate synthase and δ-guaiene synthase genes were coexpressed in this strain. This transformant was capable of liberating an appreciable amount of δ-guaiene, an aroma sesquiterpene compound accumulated in agarwood, and its concentration was elevated to more than 30 μg/ml culture by the incubation with mevalonolactone as an isoprene precursor in a nutrient-enriched Terrific broth. Coexpression of type 1 isopentenyl diphosphate isomerase plus acetoacetyl-CoA ligase genes also enhanced δ-guaiene production, and the concentration of the compound was approximately 38 - 42 μg/ml culture in the presence of mevalonolactone or lithium acetoacetate. These results clearly indicate that mevalonate pathway-engineered E. coli cells showed an appreciable δ-guaiene producing activity in the en- riched medium in the presence of appropriate isoprene precursors.
