幽门螺杆菌Cag-PAI hp0523基因的克隆及功能预测

Cloning and functional prediction of hp0523 gene from Cag-PAI in Helicobacter pylori

目的：明确幽门螺杆菌Cag-PAIhp0523基因的功能，探讨其在幽门螺杆菌致病中的作用。方法：设计引物，以幽门螺杆菌NCTC11637为模板，采用聚合酶链反应（PCR）扩增获得目的片段；将其进行T-A克隆后，进行测序。将该基因序列与其他菌株做BLAST比对分析，并结合生物信息学数据库和软件，分析其序列特征和理化特性。结果：经酶切，测序分析表明，插入的基因片断为510 bp，与基因库公布的幽门螺杆菌26695及J99序列相比较，同源性高达94%；软件预测其编码的蛋白为169个氨基酸，其相对分子质量约为19.7 kDa，等电点约为9.53；基序分析表明，在33-165位氨基酸之间存在一个保守的SLT催化基序，可能是溶菌糖基转移酶；对其催化能力进行预测，结果表明，HP0523（33.7%）催化能力可能较T4溶菌酶（32.3%）和溶菌酶SLT70（28.6%）的活性高。结论：成功克隆了幽门螺杆菌Cag-PAI的hp0523基因，对其序列进行了深入分析，为进一步研究其功能，阐明幽门螺杆菌Cag-PAI的致病机制奠定了基础。

Objective： To analyze the function and the role of hp0523 gene in Helicobacter pylori（H, pylori） Cag-PAI for pathogenicity; Methods： Polymerase chain reaction（PCR） was used to amplify the hp0523 gene from H. pylori NCTC 11637, and then cloned into the pGEM-T-easy plasmid and sequenced. Use the bioinformation databases and tools to analyze the information and properties of the target sequence. Results： Sequence analysis suggests that this fragment with 510 bp and encoded 169 aa which experiences a relative molecular weight at 19.7 kDa and isoionic point was at 9.53. The identity of this gene was 94% approximately in H. pylori strains 26695 and J99. Motif analysis suggests that it may be lytic transglycosylase, which harbored a conserved catalysis domain between 33 to 165 sites in the target sequence. From the general acid-base catalysis potential suggest that HP0523 （33.7%） with a higher catalysis activity than T4 lysozyme （32.3%） and SLT70 （28.6%）. Conclusion： The hp0523 gene was cloned from H. pylori NCTC11637 successfully, and provide a solid base for the research on the pathogenicity mechanism of H. pylori Cag-PAI.