一株盐单胞菌属(Halomonas)细菌趋化因子受体基因挖掘及相关蛋白序列分析

Digging the chemokine receptors-encoding genes and analyzing the relative protein sequences of a Halomonas strain

为了解一株长牡蛎(Crassostrea gigas)致病性盐单胞菌(Halomonas sp.)7T的趋化性,采用毛细管法研究其趋化行为,并基于全基因组数据,利用KEGG Pathway分析其趋化信号通路,通过与同源物种比对分析趋化因子受体种类,进一步挖掘甲基受体趋化蛋白(methyl-accepting chemotaxis proteins,MCPs)序列,再结合MeMe数据库和TMHMM分析MCPs结构。结果表明:Halomonas sp.7T具备趋化行为,其全基因组含有完整趋化信号通路,共有22个基因编码MCPs,涵盖5种常见趋化因子受体;22个MCPs均含有信号转导结构域,其中,19个含有跨膜结构域,3个不含跨膜结构域;基于信号转导结构域内七肽单位保守序列和存在的对称插入缺失对这22个MCPs进行分类,发现17个为36H型,1个为40H型,其余4个与已知分类均不匹配;跨膜结构分布特征和疏水性分析发现,这22个MCPs中有20个符合拓扑结构,其中ClassⅠ型、ClassⅡ型、ClassⅢ型、ClassⅣ型分别为10、4、3、3个,另有2个MCPs不符合拓扑结构。研究表明,长牡蛎致病性盐单胞菌7T具备趋化性,其基因组存在完整趋化信号通路,有22个基因编码MCPs,这些MCPs具有独特的结构,可能参与介导与细菌生存和环境胁迫响应相关的趋化行为。

With an attempt to understand the chemotaxis of Halomonas sp.7T,a pathogenic bacterium to Pacific oyster(Crassostrea gigas),its chemotaxis was investigated by capillary tube method and the holo-genome sequencing data were utilized to analyze its chemosensory signaling pathway.Genes involved in chemotaxis were predicted and the chemosensory pathway of 7T was analyzed using KEGG Pathway.The chemokine receptors-encoding genes were dug out and sequences of the relative proteins were analyzed.The chemokine receptors were further grouped via aligning and comparing with the homologues,and structures of MCPs(methyl-accepting chemotaxis proteins)were analyzed through incorporating MeMe database and TMHMM analysis.The results showed that chemotaxis was observed in Halomonas sp.7T.Across its genome,complete signaling pathways existed and there were 22 MCPs-encoding genes,covering the 5 kinds of most conventioal MCPs.Signal transduction domains were predicted in the 22 MCPs.Additionally,19 MCPs harbored the trans-membrane domain whereas 3 did not.Based on the differences in the heptapeptide repetitive sequences,the 22 MCPs were further classified into different groups.Seventeen MCPs belonged to the group of 36H and 1 MCP was in the groups of 40H,whereas the other 4 MCPs were not categorized into any known group.Additionally,20 of the 22 MCPs harbored trans-membrane domains conforming to topology,among which 10 were grouped to ClassⅠ,4 to ClassⅡ,3 to ClassⅢ,and 3 to ClassⅣ.The results showed that chemotaxis was observed in Halomonas sp.7T,a bacterial strain pathogenic to Crossostrea gigas.Complete chemosensory signaling pathways existed in its genome.In total,22 genes encoded methyl-accepting chemotaxis proteins,which were of specific structural characteristics and might be involved in mediating chemotactic behaviours crucial to the existence as well as responses to environmental stresses of the bacterial strain.