单核细胞增生李斯特菌新疆野毒株XS5 SigmaB操纵子的克隆、序列分析及其编码蛋白结构预测

为了解单核细胞增生李斯特菌(Listeria monocytogenes LM.)新疆野毒株XS5 SigmaB操纵子的分子生物学特征。对LM-XS5的SigmaB操纵子部分基因序列进行了克隆与序列分析，预测该操纵子各基因编码蛋白质的二三级结构及功能活性位点，分析其同源性。结果表明：成功扩增出3000 bp的SigmaB操纵子片段，序列分析显示该片段中包含RsbV、RsbW、RsbX和SigmaB 4个基因，它们编码的蛋白质含有不同的功能活性位点，其中RsbV的5~102位AA为“STAS-抗-抗-SigamB因子”，RsbW的43~157位AA间为HATPase_c功能域，RsbX的32~198位AA间为PP2Cc超家族区域，SigmaB的8~264位AA为RNA聚合酶全酶中的SigmaB因子的区域。LM-XS5与其他3种革兰氏阳性菌的SigmaB基因的同源率在50%左右，与LM参考株的同源率在92.18%~100%之间。

Cloning, Sequence Analysis and the Prediction of the Protein Structure of SigmaB Operon Sequence of XinjiangStrain XS5 of Listeria monocytogenes

In order to understand the biological characteristics of the SigmaB operon of Xinjiang Strain XS5 of Listeria monocytogenes, a part of SigmaB operon sequences of XS5 was amplified using PCR technique, then cloned and analyzed. The secondary and tertiary structure were predicted and analyzed for all the genes in SigmaB operon. Identity of SigmaB gene was analyzed among LM-XS5 and reference strains of LM together with other three kinds of gram-positive bacteria, and then Phylogenetic trees was constructed by MEGA5. The results showed that the amplified fragment of 3000 bp contained four genes (RsbV, RsbW, RsbX and SigmaB). All of them had different functional domains which were structural basis of their functions. The 5 to 102 AA of RsbV was "STAS-anti-anti-SigamB factor"; the 43 to 157 AA of RsbW was HATPase_c; the 32 to 198 AA of RsbX belonged to PP2Cc super family; the 8 to 264 AA of SigmaB was SigmaB factor of RNA polymerase. Compared with the SigmaB gene sequence of other three kinds of gram-positive bacteria, the identities were around 50%, and the identities among strains of LM ranged from 92.18% to 100%.