Chlamydial type III secretion system is encoded on ten operons preceded by sigma 70-like promoter elements
Chlamydial type III secretion system is encoded on ten operons preceded by sigma 70-like promoter elements
复制标题
DOI：
10.1128/jb.01034-06
复制
发表时间：
2007-01-01
影响因子：
3.2
通讯作者：
Stephens, Richard S.
中科院分区：
文献类型：
--
作者：
Hefty, P. Scott;Stephens, Richard S.
许多革兰氏阴性细菌病原体采用III型分泌系统进行感染过程。衣原体是专性细胞内细菌，编码保守的III型分泌系统，这可能是生长所必需的。通常，编码III型分泌系统的基因位于单个位点；然而，对于衣原体来说，这些基因分散在整个基因组中。关于这一重要的毒力决定因素的基因调控机制知之甚少。为了方便鉴定顺式作用的转录调控元件，我们确定了操纵子的结构。该分析揭示了10个操纵子包含37个与III型分泌系统相关的基因。这些操纵子内的连锁表明这些基因中的每一个都在III型分泌中起作用，其中包括13个编码功能未知的蛋白质的基因。确定了每个操纵子的转录起始位点。结合启动子活性分析，该分析显示III型分泌系统操纵子编码sigma（70）样启动子元件。负责组成基因表达的sigma因子的转录起始表明，未定义的激活因子或抑制因子调节衣原体III型分泌系统基因的发育阶段特异性表达。
Many gram-negative bacterial pathogens employ type III secretion systems for infectious processes. Chlamydiae are obligate intracellular bacteria that encode a conserved type III secretion system that is likely requisite for growth. Typically, genes encoding type III secretion systems are located in a single locus; however, for chlamydiae these genes are scattered throughout the genome. Little is known regarding the gene regulatory mechanisms for this essential virulence determinant. To facilitate identification of cis-acting transcriptional regulatory elements, the operon structure was determined. This analysis revealed 10 operons that contained 37 genes associated with the type III secretion system. Linkage within these operons suggests a role in type III secretion for each of these genes, including 13 genes encoding proteins with unknown function. The transcriptional start site for each operon was determined. In conjunction with promoter activity assays, this analysis revealed that the type III secretion system operons encode sigma(70)-like promoter elements. Transcriptional initiation by a sigma factor responsible for constitutive gene expression indicates that undefined activators or repressors regulate developmental stage-specific expression of chlamydial type III secretion system genes.