嗜酸氧化亚铁硫杆菌细胞色素C家族afe_0378基因转录表达差异及生物信息学挖掘

Differential of Transcription Expression&Bioinformatics Tapping of a Cytochrome c Family Gene of afe_0378 in Acidithiobacillus ferrooxidans

嗜酸氧化亚铁硫杆菌是一种极为重要的浸矿微生物,具有氧化各种还原性含硫物及亚铁等功能。采用实时荧光定量PCR技术及生物信息学等手段对该菌一个涉及铁硫氧化由afe_0378基因编码的细胞色素C家族蛋白CycA2进行了研究。结果表明,afe_0378基因在单质硫培养条件下转录水平是亚铁培养条件下的2.67倍。生物信息学分析表明afe_0378编码蛋白CycA2是分子质量为22.959 ku,pI为9.75的结合内膜的周质蛋白,二级结构为全α-螺旋,无β-折叠,包含2个相似结构域及N端一段跨膜疏水螺旋,属于细胞色素C4型蛋白家族。CycA2蛋白分子三维结构模建表明,双血红素与CycA2蛋白序列片段域C48-X-X-C51-H52及C149-X-X-C152-H153中的半胱氨酸共价连接。结合该菌硫代谢背景知识,推测CycA2蛋白的功能是介导细胞色素bc1复合体及终端氧化酶细胞色素aa3复合体之间的电子传递而参与硫代谢。

Acidithiobacillus ferrooxidans is a very important ore-immersing microbe possessing the functions of oxidation of various reductive inorganic sulfur compounds and ferrous.In this study quantitative real-time PCR and bioinformatic means were adopted to carry out the study involving cytochrome protein family aims at the CycA2 protein involved iron and sulfur oxidation encoded by gene afe_0378.The results showed that the down transcription level under sulphur simple substance-culturing conditions of afe_0378 gene was 2.67-fold of that under ferrous culturing conditions.Bioinformatic analyses suggested that the molecular weight of afe_0378 gene encoded CycA2 was 22.959 ku,endomembrane combined periplasmic protein of pI at 9.75.Its secondary structure was all α-helix without β-folding,and composed of two similar domains and a N-terminal transmembrane hydrophobic helix,and belonged to C4type protein family.The established model of CycA2 protein molecular three dimensions structure suggested that di-heme was linked covalently with cysteine of C48-X-X-C51-H52 and C149-X-X-C152-H153 in CycA2 protein sequence fragments domains.Combining the background knowledge about sulfur oxidation,it was speculated that the function of CycA2 was electron communication that intermediated cytochrome bc1complex and terminal oxidase cytochrome aa3complex participating in sulfur oxidation in Acidithiobacillus ferrooxidans.