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.
