【摘要】 从青霉素工业生产菌产黄青霉(Penicilliumchrysogenum)中首次克隆了一个谷胱甘肽S-转移酶(GST)基因,定名为PcgstA.该基因的开放阅读框长840bp,含有两个内含子,编码一个238氨基酸残基的蛋白质.其推断的氨基酸序列与一些已经鉴定的丝状真菌GST具有50%左右的序列一致性.PcgstA的完整编码区经RT-PCR扩增、验证,插入原核表达载体pET11a,转化大肠杆菌BL21(DE3)-RP菌株,表达得到重组PcGSTA蛋白.酶活测定证实,重组PcGSTA具有GST活性,其对底物CDNB(1-chloro-2,4-dinitrobenzene)的比活为(0.159±0.031)μmol/(min·mg).利用TaqMan探针法,对PcgstA的表达情况进行了比较.结果表明,在添加了侧链前体苯乙酸的青霉素生产培养基中,PcgstA的表达水平和在不含苯乙酸培养基中的表达相比明显下调,显示了该基因与苯乙酸代谢的关系.更多还原

【Abstract】 Glutathione S-transferase (GST) gene, PcgstA was cloned from the penicillin producing strain Penicillium chrysogenum, which is important for understanding the industrial fermentation process. PcgstA gene has an open-reading-frame of 840 bp in length, which is interrupted by two introns. The deduced amino acid sequence shows about 50% identity to several characterized filamentous fungi GSTs. The recombinant PcGSTA in Escherichia coli were overexpressed and purified. Enzymatic assays showed that the recombinant PcGSTA had a specific activity with 1-chloro-2, 4-dinitrobenzene of (0.159±0.031) μmol/(min·mg). It was found that the expression level of PcgstA in the penicillin producing medium supplemented with phenylacetic acid, the side chain precursor of penicillin G, was significant down regulated than that in medium without phenylacetic acid. This result suggested that PcGST may be related to phenylacetic acid metabolism in the penicillin producing strain.更多还原