两个溶藻弧菌胞外多糖合成基因簇的生物信息学分析

Identification of the Functions of Two Gene Clusters Putatively Involved in Extracellular Polysaccharides Biosynthesis in Vibrio alginolyticus ZJ-51

溶藻弧菌是我国南方海水养殖最重要的病原菌之一。胞外多糖(EPSs)是细菌产生的一类具有复杂结构的多糖类物质,影响其致病性和环境适应力。基因组分析发现溶藻弧菌ZJ-51存在4个与胞外多糖合成有关的基因簇,笔者对其中2个基因簇CPS1357和CPS4543进行了生物信息学分析和实验验证。结果表明,基因簇CPS4543编码3个多糖外膜转运体系的同源蛋白Wza-Wzb-Wzc,而CPS1357编码的17个蛋白与多糖合成、转运以及调控有关。但通过染色实验、菌落形态观察和运动性分析证实这2个基因簇的缺失并不影响EPSs的合成、生物膜的形成、菌落形态及运动性。这可能是这2个基因簇在当前测试条件下受到抑制或需要特殊的环境因子诱导表达,对溶藻弧菌EPSs合成调控机制的研究,能更好地了解该病原菌在环境中的适应性。

Vibrio alginolytieus is one of the most important pathogens for seafood-borne infection in South China. Extracellular polysaccharides （EPSs） are a type of polysaccharides produced by bacteria with a complex struc- ture, and affect the pathogenicity and environmental adaptability of pathogens. Genomic analysis shows that a- bout four gene clusters related to the synthesis of exopolysaccharides exist in V. alginolyticus ZJ-51. In this stud- y, bioinformatic analysis and verification experiment were used to find out the potential functions of two gene clusters of them, i.e. CPS1357 gene cluster and CPS4543 gene cluster. The results show that the gene cluster CPS4543 encoded three homologous proteins Wza-Wzb-Wzc forming an outer membrane transport system for pol- ysaccharides synthesis, while CPS1357 encoded 17 proteins which were responsible for the synthesis, transporta- tion and regulation of polysaccharides. However, the loss of these two gene clusters resulted in no change of EPSs biosynthesis, biofilm formation, colony morphology and mobility. This may be due to the fact that these two gene clusters were inhibited under the current test conditions or that some of special environmental factors were required to induce their expression. More studies of EPSs synthesis mechanism in V. alginolyticus should be taken to help better understand the adaptability of this species of bacteria in the environments.