Cloning and expression analysis of a polyketide synthase gene vv-alb from the edible straw mushroom, Volvariella volvacea
草菇聚酮合酶编码基因vv-alb的克隆及其表达的初步分析

Polyketides are secondary metabolites that exhibit a broad range of biological activities. The key enzyme involved in biosynthesis is polyketide synthase (PKS). We report the cloning of a putative PKS gene (vv-alb) by nested PCR using degenerate primers and chromosome walking from the edible straw mushroom, Volvariella volvacea. The gene vv-alb is 6,704bp in size and contains a 6,279bp coding region (encoding 2,093 amino acid residues) and eight introns. The encoded product of the vv-alb gene contains four functional domains: ketosynthase (KS), acyl transferase (AT), thioesterase (TE) and acyl carrier protein (ACP), the typical characteristics of PKS. Real-time quantitative PCR analysis revealed that vv-alb expression was 5-10-fold higher in the stipe region as compared with the vegetative mycelium, primordia and pileus.