摘要
通过反向PCR和细菌Fosmid文库筛选,克隆得到1株三价砷[As(Ⅲ)]氧化细菌Acidovorax sp.GW2的As(Ⅲ)氧化酶Aox基因簇,包括aoxRSXABCD7个基因,分别预测编码双组分信号传导系统转录调控子AoxR(同源性68%),周质感应组氨酸激酶AoxS(同源性55%),周质结合蛋白AoxX(同源性55%),砷氧化酶AoxAB(同源性分别为74%和71%),硝基还原酶AoxC(同源性46%),细胞色素c AoxD(同源性63%)。反转录PCR结果显示,编码双组分系统的aoxRS基因共转录,而与之转录方向相反的结构基因aoxABCD处于同一操纵子中,aoxX基因和aoxRS基因不在同一操纵子中。通过对aoxS、aoxX、aoxD的基因敲除功能研究发现aoxS和aoxX基因为GW2三价砷氧化的必需基因,aoxD的功能丧失减慢了三价砷的氧化速率,但非关键基因。
Using reverse transcriptase PCR method and a bacterial fosmid library screening,an arsenite oxidase gene cluster were isolated from an arsenite-oxidizing bacterium Acidovorax sp.GW2.There are seven genes including aoxRSXABCD putatively encoding the transcriptional regulator AoxR of a two-component signal transduction system （68% identity）,a periplasmic sensor histidine kinase AoxS （55% identity）,a periplasmic binding protein AoxX （55% identity）,arsenite oxidase AoxAB（74% and 71% identity,respectively）,nitroreductase AoxC （46% identity） and cytochrome c AoxD （63% identity） respectively.According to the reverse transcriptase PCR experiments,aoxR and aoxS encoding for a two-component system proteins are co-transcribed and located in opposite to structural genes aoxABCD.aoxX and aoxRS are not in the same operon.Functional analyses through gene knock-out of aoxS,aoxX and aoxD showed that aoxS and aoxX are the essential genes in arsenite oxidation of GW2,and the loss of aoxD did not show significant effects on arsenite oxidation.
出处
《华中农业大学学报》
CAS
CSCD
北大核心
2011年第1期23-29,共7页
Journal of Huazhong Agricultural University
基金
国家自然科学基金项目(30970075)
"863"计划(2007AA06Z332)
