阿维链霉菌中ECF-Sig16对阿维菌素合成的影响

Effect of ECF-Sig16 on Avermectin Production in Streptomyces avermitilis

阿维菌素是阿维链霉菌产生的一种广谱、高效、低毒的杀虫抗生素,在医药、农业和畜牧业领域有着广泛的应用。ECF-Sigma因子在细菌适应生存环境变化和高效响应激活压力中起重要作用。为研究阿维链霉菌中ECF-Sig16因子对阿维菌素合成的影响,通过对sig16基因缺失、回补和过表达,利用摇瓶发酵试验初步证实Sig16能够抑制阿维菌素的合成,但不影响菌株的生长。表型观察试验显示Sig16不影响阿维链霉菌的形态分化。通过凝胶阻滞试验(EMSA)确定Sig16直接结合在支链氨基酸ABC转运体操纵子SAV1190~SAV1194的启动子区,暗示Sig16可能通过影响阿维菌素生物合成的前体物质,抑制阿维菌素的合成。

Streptomyces avermitilis produces avermectin,which is a kind of anthelmintic antibiotics with broadspectrum,low toxicity activities and high potency and widely used in agricultural and medical fields.Extracytoplasmic function Sigma(ECF-Sigma)regulators play key roles for adaptation to changes of living environment and activating stress responses efficiently.To investigate the function of ECF-Sig16 regulator in avermectin biosynthesis,shaking flask fermentation of sig16 gene deletion,complementary,and overexpression strains were test.The results indicated that Sig16 inhibited avermectin biosynthesis,but exerted no function on cell growth.Phenotype observation experiment showed that Sig16 didn’t affect Streptomyces avermitilis morphological differentiation in some conditions.Electrophoretic mobility shift assay(EMSA)showed that Sig16 binded to the promoter of branched-chain amino acid ABC transporter operon SAV1190~SAV1194,which indicated Sig16 could inhibit avermectin production by affecting avermectin precursor supply.