Analyses of sigma factor 28 of C. trachomatis

描述（由申请人提供）：沙眼衣原体是细菌性传播感染的主要原因。这种重要病原体的基因表达调控尚不清楚。我们的长期目标是研究沙眼衣原体在不同条件下存活、在宿主体内持续存在并导致人类疾病的全球调控机制。我们已经证明，沙眼衣原体替代sigma因子，sigma 28，对热休克有反应，并识别衣原体的hctB启动子和大肠杆菌的flc启动子。这表明sigma28可能参与了一组基因的转录，这些基因是适应反应所必需的，能够成功完成发育周期。本提案的目的是了解衣原体sigma因子之一sigma28的生物学功能，并表征其调节因子。我们提出了两个具体目标：1)我们将鉴定和表征沙眼衣原体中依赖sigma28的启动子和sigma28调控的靶基因。我们还将研究这些启动子及其相关靶基因在衣原体生理相关条件下的活性。2)我们将鉴定和表征衣原体中sigma28的推定调节因子，并研究sigma28与其推定调节因子之间相互作用对sigma28特异性转录的影响。从这些研究中获得的信息可能有助于更好地了解沙眼衣原体的基因全局调控、细胞内寄生、毒力、免疫逃避和持久性。

DESCRIPTION (provided by applicant): Chlamydia trachomatis is a major cause of bacterial sexually transmitted infections. The regulation of gene expression in this important pathogen has not been well understood. Our long-range goals are to investigate the global regulatory mechanisms that allow C. trachomatis to survive in different conditions, as well as to persist in the host and contribute to human disease. We have demonstrated that the C. trachomatis alternative sigma factor, sigma 28, responds to heat shock and recognizes the hctB promoter of Chlamydia and also the fliC promoter of Escherichia coli. This suggests that sigma28 may be involved in transcription of a group of genes, which are required for an adaptation response enabling the successful completion of the developmental cycle. The objective of this proposal is to understand the biological function of one of the chlamydial sigma factors, sigma28, and to characterize its regulator(s). We propose two specific aims: 1) We will identify and characterize sigma28-dependent promoters and the sigma28 regulated target genes in C. trachomatis. We will also examine the activities of these promoters and their related target genes under conditions that are physiologically relevant for Chlamydia and 2) We will identify and characterize the putative regulator(s) of sigma28 in Chlamydia, and examine the effect on sigma28 specific transcription of interactions between sigma28 and its putative regulators. Information derived from these studies may lead to a better understanding of global regulation of genes, intracellular parasitism, virulence, immune evasion and persistence of C. trachomatis.