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

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

为了解单核细胞增生李斯特茵（Listeda monocytogenes LM．）新疆野毒株XS5SigmaB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3000bp的SigmaB操纵子片段，序列分析显示该片段中包含Rsb认RsbW,RsbX和SigmaB4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”，咫6Ⅳ的43-157位AA间为HATPasec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种革兰氏阳性茵的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。

In order to understand Listeria monocytogenes, a part of the biological characteristics of the SigmaB operon of Xinjiang Strain XS5 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 SigrnaB 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 （Rsb V, Rsb W, RsbX and SigmaS. All of them had different functional domains which were structural basis of their functions. The 5 to 102 AA ofRsbVwas ＂STAS-anti-anti-SigaraB factor＂; the 43 to 157 AA of RsbWwas 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%.