溶藻弧菌Ⅲ型分泌系统分子伴侣护航蛋白VscO的基因克隆及其生物信息学分析

Molecular Cloning and Bioinformatics Analysis of T3SS Chaperone Escort Protein VscO from Vibrio alginolyticus

克隆了溶藻弧菌(Vibrio alginolyticus)ZJ03株Ⅲ型分泌系统(T3SS)分子伴侣护航蛋白(Chaperone escort protein)vscO基因,并对其进行生物信息学分析。结果表明,vscO基因全长462 bp,编码153个氨基酸,理论分子量约为18.43 kD,pI值为9.22。细胞定位分析显示vscO基因位于外周质,不存在信号肽,无跨膜区。vscO基因具有转录起始区-35区和-10区,以及翻译识别信号SD序列(Shine-Dalgarno sequence)。该氨基酸序列含有多种活性位点,如蛋白激酶C磷酸化位点等。系统进化树发现溶藻弧菌的VscO蛋白与副溶血弧菌聚为同一亚族。VscO亚基三维结构模型显示其与副溶血弧菌T3SS的YscO蛋白有相似构型。信号通路分析推测VscO位于T3SS的针状样结构上。蛋白网络互作图谱发现VscO与10种T3SS蛋白具有相邻关系。本研究结果将为溶藻弧菌Ⅲ型分泌系统护航机制的研究奠定基础。

Primers for PCR cloning were designed according to the whole genome sequence of Vibrio alginolyticus published in GenBank. The type III secretion system（T3SS）chaperone escort protein vscO gene of V.alginolyticus strain ZJ03 was amplified by PCR and cloned into pMD18-T vector. Sequence analysis revealed that vscO gene is 462 bp and encodes a putative protein of 153 amino acids. The predicted molecular weight（MW）of VscO was 18.43 kD with an estimated pI of 9.22. Using SignalP 4.0 and TMHMM Server 2.0 software, it was predicted that the VscO protein was located in periplasm. It did not contain a signal peptide or a transmembranous region. The vscO gene with transcription initiation region at-35 and-10 region, and a translation recognition signal sequence（SD Shine-Dalgarno sequence）. This protein had some active sites, such as phosphorylation sites. To further analyze the evolutionary relationship among VscO, a molecular phylogenetic tree was constructed using Mega 5.0 software. In this tree, the VscO protein showed high genetic relationship with Vibrio parahaemolyticus. The three-dimensional structure of VscO was determined using SWISS-MODEL work-space and it had a similar structure with YscO protein of V. parahaemolyticus. Signaling pathway analysis showed that VscO is located at the“needle”site of T3SS. Protein interaction map network found that the relation between VscO and 10 kinds of T3SS proteins was neighbourhood. These results can provide a basis for further studies on the chaperone escort machanism used by T3SS export pathway of Vibrio species.