【摘要】 目的分枝杆菌中类固醇3β位脱氢酶(3β-HSD)及其同工酶是植物甾醇降解过程中的关键限速步骤,本文作者在基因水平上确证其组成和生物学功能。方法以结核分枝杆菌中功能明确的Rv1106c基因序列为模板在新金分枝杆菌基因组中进行序列比对,对基因片段进行体外表达验证其活性,再通过基因敲除验证其在类固醇代谢中的生理功能。结果在新金分枝杆菌基因组中筛选获得4条类固醇3位脱氢酶基因同源序列,具有3β羟基氧化功能,敲除突变菌株对植物甾醇代谢只减慢约10%。结论证实了新金分枝杆菌中有多个3β位脱氢酶基因参与类固醇的代谢。更多还原

【Abstract】 Objective 3β-hydroxyl steroid dehydrogenases and isoenzymes(3β-HSD/isomerases)are the key rate-limiting steps in the degradation of phytosterols in mycobacteria.To confirm their compositions and biological functions at the genetic level.Methods The function of Rv1106c gene in Mycobacterium tuberculosis H37 Rv had been verified and was used as reference sequence to identify putative 3β-hsd genes in Mycobacterium neoaurumDSM44074 genome.Four putative genes were identified and expressed heterologously for 3β-hsd activity.Their physiological roles as 3β-hydroxyl dehydrogenasein phytosterol metabolism were verified by gene knockout.Results Four functional 3β-hydroxyl dehydrogenase genes were discovered in Mycobacterium neoaurumDSM44074.The metabolism level of phytosterols in the knockout mutant of all these four genes was reduced by 10%.Conclusion Besides choM1,choM2 and the four hsd genes,there are more genes involved in 3β-hydroxyl steroid dehydrogenation in Mycobacterium neoaurumDSM44074.更多还原