水产品腐败希瓦氏菌冷激蛋白的结构与功能分析

Structural and Functional Analysis of Cold Shock Protein in Shewanella putrefaciens from Aquatic Products

腐败希瓦氏菌是冷藏鱼类的特定腐败菌,具有较强的低温适应能力,在冷藏条件下仍能生长而引起鱼类腐败。冷激蛋白(CSP)是影响细菌低温适应能力的一种关键蛋白。本研究通过PCR扩增获得水产品腐败希瓦氏菌的3个CSP基因,并通过生物信息学手段对其结构和功能进行分析。结果表明:腐败希瓦氏菌冷激蛋白Csp1589和Csp1376与大肠杆菌CspA亲缘关系较近,而Csp2252与大肠杆菌CspD相似性更高;CSP分子质量均在7.4 ku左右,为亲水的小分子酸性蛋白质,皆定位于细胞质,为非分泌型、非跨膜蛋白,都存在CSP特有的冷休克结构域,存在能与单链DNA和RNA结合的位点和基序。蛋白的二级结构和三级结构均符合CSP家族的特征,包含5个反向平行β-折叠。预测3个冷激蛋白在功能上分别与多种蛋白相互作用,包括参与双组分信号转导系统的组氨酸激酶,参与DNA复制的DNA聚合酶及伴侣蛋白htpG等。同时预测CSP可能的配体结合位点,为进一步阐明冷激蛋白在腐败希瓦氏菌低温适应过程中的功能提供一定参考。

As a specific spoilage organism of refrigerated fish,Shewanella putrefaciens can survive longer during cold storage due to its strong adaptability to cold and cause the fish spoilage.Cold shock protein(CSP)is one of the key proteins that affects the adaptability of bacteria to low temperature.In the present study,three CSP genes were obtained by PCR amplification,and their structure and function were analyzed by bioinformatics.The results showed that the Csp1589 and Csp1376 of S.putrefaciens shared close homology with Escherichia coli CspA,while Csp2252 was more homology with E.coli CspD;the CSPs were small hydrophilic acidic protein with molecular weight of about 7.4 ku,all of which were located in the cytoplasm and are non-secretory and non-transmembrane proteins.All of them possess specific cold shock domain,and sites and motifs that could bind to single-stranded DNA and RNA.The secondary and tertiary structures of CSPs conformed to the characteristics of CSP family,which contained five reverse parallelβ-strands.Three CSPs were functionally predicted to interact with various proteins,including histidine kinase involved in two-component signal transduction system,DNA polymerase involved in DNA replication,chaperone protein htpG,etc.And the possible ligand binding sites of CSP were predicted.It provided some references for further elucidation of the function of CSPs in the process of low temperature adaptation of S.putrefaciens.