红色红曲菌M7中色素聚酮合酶基因敲除突变体的鉴定

Identification of a pigment-polyketide synthase gene deleted mutant of Monascus ruber M7

摘要:

摘要:【目的】研究红色红曲菌(Monascus ruber) M7中控制红曲色素合成的聚酮合酶基因(pksPT)的功能。【方法】对M7 中pksPT进行了生物信息学分析;借助农杆菌介导的红曲菌转化技术敲除M7中pksPT，获得pksPT缺失突变体(ΔpksPT)，比较M7和ΔpksPT菌落形态、产孢能力、生长速度、色素和桔霉素产量的差异。【结果】pksPT全长8687 bp，编码蛋白含有2690个氨基酸，属于非还原Ⅲ型聚酮合酶，包括β-酮酯酰基合成酶(KS)、酰基载体蛋白(ACP)、酰基转移酶(AT)和甲基转移酶(ME)四种结构域，组合形式为KS-AT-ACPACP-ME。ΔpksPT的分析结果显示，pksPT的敲除不影响其产分生孢子和闭囊壳的能力;ΔpksPT不能产生任何一种红曲色素;其生长速度明显快于野生菌株M7;桔霉素产量较M7 提高了2.8倍。【结论】pksPT是M7中控制红曲色素合成的关键基因，红曲色素的合成显著影响红曲菌产桔霉素能力和生长速度。

Abstract:

Abstract:［Objective］ To reveal the function of a polyketide synthase gene (pksPT)，probably responsible for the synthesis of Monascus pigments in Monascus ruber M7.［Methods］The pksPT was analyzed using bioinformatics method; it was disrupted using Agrobacterium tumefaciens mediated transformation method，generating the pksPT-deleted mutant (ΔpksPT)．Colonial morphology，conidial germination，pigment and citrinin production，and growth rate of ΔpksPT were analyzed.［Results］The pksPT with the length of 8687 bp encoded a putative protein of 2690 amino acids，which is a non-reduced type III polyketide synthase and has some active domains with the arrangement of KS (β-ketosynthase)-AT (Acyltransferase)-ACP (Acyl carrier protein)-ACP-ME (Methyltransferase)．The analysis of ΔpksPT displayed that it could generate cleistothecum and conidum normally and was unable to produce any kinds of Monascus pigments; compared to M7，the growth rate of ΔpksPT was increased obviously and the yield of citrinin in ΔpksPT was increased about 2.8 times.［Conclusion］pksPT is of extremely importance to the biosynthetic pathways of Monascus pigments in M7 and the synthesis of Monascus pigments gives a significant effect on the produce of citrinin as well as the growth of M7.