大肠杆菌Top10Na^+/H^+反向运输体A基因的克隆及生物信息学分析

Molecular Cloning and Bioinformatics Analysis of Na^+/H^+ Antiporter A Gene in Escherichia coli Top10

根据细菌中存在的Na+/H+反向运输体(Na+/H+antiporterA,nhaA)的基因序列,采用PCR扩增的方法从大肠杆菌(Escherichia coli)Top10中克隆到了nhaA基因(Acession Numeber:EU368045)。nhaA开放阅读框为1 167 bp,编码含有388个氨基酸残基,分子量为41.3 kDa的蛋白,预测等电点为9.23。nhaA含有25个碱性氨基酸,19个酸性氨基酸,211个疏水氨基酸及63个极性氨基酸。二级结构预测表明,该蛋白含约50%的α-螺旋、18%的延伸链、7%的β-转角和25%的不规则卷曲。亲疏水性分析显示,nhaA是疏水性蛋白。跨膜结构进行分析显示该蛋白含有11个跨膜区域。序列分析表明,大肠杆菌Top10 nhaA基因与大肠杆菌DH5α、大肠杆菌HS、大肠杆菌SECEC SMS-3-5和大肠杆菌CFT073的nhaA基因同源性分别为100%、98%、95%和92%。大肠杆菌Top10 nhaA基因的克隆及生物信息学分析为今后对nhaA的进一步深入研究奠定了基础。

nhaA （Na^＋/H^＋ antiporter A） was cloned from Escherichia coil Top10 by PCR, with primers designed according to public nhaA sequences. The open reading frame of nhaA gene has 1167 bp in length and encodes a protein of 388 amino acid residues. The estimated molecular weight and isoelectric point of the putative protein were 41.3 kDa and 9.23, respectively. Components of amino acids encoded nhaA contained 25 basic amino acids, 19 acidic amino acids, 211 hydrophobic amino acids and 63 polar amino acids. The predicted secondary structure of the protein had about 50% alpha helixes, 18% extended strand, 7% beta turn and 25% random coil. Hydrophobic analysis indicted that nhaA was a hydrophobic protein, nhaA contained 11 transmembrane segments. It shared 100 %, 98 %, 95 % and 92 % homologies in DNA sequence level with E.coli DH5 or, E. coli HS, E.coli SECEC SMS-3-5 and E.coli CFT073, respectively. Molecular cloning and bioinformatics analysis of nhaA in Escherichia coli Top10 will be helpful for the further analysis of nhaA.