ChxR is a transcriptional activator in Chlamydia
ChxR is a transcriptional activator in Chlamydia
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DOI：
10.1073/pnas.0509690103
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发表时间：
2006-01-17
影响因子：
11.1
通讯作者：
Stephens, RS
中科院分区：
文献类型：
--
作者：
Koo, IC;Walthers, D;Stephens, RS
衣原体属物种是专性细胞内细菌病原体，在两种代谢和形态上不同的发育形式之间交替，分化取决于转录调控。沙眼衣原体的基因组测序揭示了一个ORF，CT630（chxR），其氨基酸序列包含一个有翼的螺旋-转角-螺旋基序，类似于OmpR亚家族中反应调节因子的DNA结合结构域。ChxR与许多反应调节剂的不同之处在于缺乏受体或磷酸化结构域中的必需残基。ChxR作为转录调节因子发挥作用，因为它在大肠杆菌中表达时激活ompF和ompC的转录。结合微阵列分析的体外转录也表明，ChxR通过直接结合chxR上游位点激活自身表达;它还激活infA、tufA、oppA和CT 084。DNA酶I保护研究表明，ChxR结合的ompF和ompC启动子近端区域的重叠，但不同的OmpR结合位点。这两种蛋白质可以同时结合到它们的非重叠结合位点。这份报告确定了一个阶段特异性转录调控因子和它的一些靶基因在衣原体。
Chlamydia spp. are obligate intracellular bacterial pathogens that alternate between two metabolically and morphologically distinct developmental forms, and differentiation depends on transcriptional regulation. Genome sequencing of Chlamydia trachomatis revealed an ORF, CT630 (chxR), whose amino acid sequence contains a winged helix-turn-helix motif similar to the DNA-binding domain of response regulators in the OmpR subfamily. ChxR differs from many response regulators in that essential residues in the receiver or phosphorylation domain are lacking. ChxR functions as a transcriptional regulator because it activated transcription of ompF and ompC when expressed in Escherichia coli. in vitro transcription combined with microarray analysis also demonstrated that ChxR activates its own expression by binding directly to sites upstream of chxR; it also activates infA, tufA, oppA, and CT084. DNase I protection studies showed that ChxR bound to sites in the ompF and ompC promoter proximal regions that overlap but were distinct from OmpR binding sites. Both proteins could bind simultaneously to their nonoverlapping binding sites. This report identifies a stage-specific transcriptional regulator and some of its target genes in Chlamydia.