致病菌III型分泌系统分子伴侣序列保守性分析及新伴侣的预测

很多革兰氏阴性致病菌使用Ⅲ型分泌系统(type Ⅲ secretion system，TTSS)将毒力因子直接注射到宿主细胞质中，其中某些效应蛋白(即毒素)需要专一的Ⅲ型分泌系统分子伴侣才能有效分泌。尽管2000年Cheng等提出这些分子伴侣中应该存在保守的氨基酸序列或保守的分泌信号，但是以往的研究并没有发现保守的氨基酸序列或分泌信号。文章作者通过生物信息学模体搜索对45个Ⅲ型分泌系统分子伴侣的氨基酸序列进行分析，找出5个与Ⅲ型分泌系统分子伴侣功能有关的保守模体和模体组合。其中一个为已知的，一个比已知的34氨基酸多肽重复(tetratdco peptide repeat，TPR)模体更具有Ⅲ型分泌系统分子伴侣SycD家族特征，其他3个为新的模体。每个Ⅲ型分泌系统分子伴侣家族包含一个或多个模体，这揭示了同类分子伴侣序列中确实存在保守的位点，暗示着同类分子伴侣可能存在相同的空间结构和功能，进一步支持了Birtanlan有关相同的空间结构具有普遍TTSS三维分泌信号的假说，并基于此分析和同源分析预测出27个新的可能的Ⅲ型分泌系统分子伴侣。

Conservative analysis of type III secretion system chaperone protein sequence and prediction of new chaperone

Many Gram negative pathogen utilize type III secretion system (TTSS) to inject toxins into the cytosol of eukaryotic cell. Some effector proteins (toxins) are secreted by their cognate chaperones through the TTSS. Previous studies indicated that there is little amino-acid sequence similarity among these chaperones. However, by bioinformatics methods, we find that many chaperones have more than one homologous chaperones, and two known motifs and three newly identified motifs exist widely in these chaperones which indicate that there must exist some conservative sites in TTSS chaperones protein sequences. Base on above, we predicted 27 new prossible TTSS chaperones.