The gram-negative, obligate intracellular human pathogen, Chlamydia trachomatis has a bi-phasic developmental cycle. The histone H1-like C. trachomatis DNA binding protein, Hc2, is produced late during the developmental cycle when the dividing reticulate body transforms into the smaller, metabolically inactive elementary body. Together with Hc1, the two proteins compact the chlamydial chromosome and arrest replication and transcription. Hc2 is heterogeneous in length due to variation in the number of lysine rich pentamers. Six pentamers and one hexamer constitute a 36 amino acid long repetitive unit that, in spite of variations, is unique for Chlamydiaceae. Using synthetic peptides, the DNA-binding capacity of the 36 amino acid peptide and that of a randomized peptide was analyzed. Both peptides bound and compacted plasmid DNA, however, electron microscopy of peptide/DNA complexes showed major differences in the resulting aggregated structures. Fluorescence spectroscopy was used to analyze the binding. After complexing plasmid DNA with each of three different intercalating dyes, increasing amounts of peptides were added and fluorescence spectroscopy performed. The major groove binder, methyl green, was displaced by both peptides at low concentrations, while the minor groove binder, Hoechts, and the intercalating dye, Ethidium Bromide, were displaced only at high concentrations of peptides.

中文翻译：

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沙眼衣原体Hc2蛋白的重复36个氨基酸基序与DNA的主要沟结合。

革兰氏阴性专性细胞内人类病原体沙眼衣原体具有双相发育周期。组蛋白H1样沙眼衣原体DNA结合蛋白Hc2在发育周期的后期产生，当分裂的网状体转变为较小的，代谢不活跃的基本体时。两种蛋白与Hc1一起压实衣原体染色体并阻止复制和转录。由于富含赖氨酸的五聚体数目的变化，Hc2的长度不均一。六个五聚体和一个六聚体构成了一个36个氨基酸长的重复单元，尽管存在变异，但对于衣原体而言却是唯一的。使用合成肽，分析了36个氨基酸的肽和随机肽的DNA结合能力。两种肽都结合并压缩了质粒DNA，但是，肽/ DNA络合物的电子显微镜显示了所得聚集结构的主要差异。荧光光谱法用于分析结合。将质粒DNA与三种不同的嵌入染料复合后，添加越来越多的肽并进行荧光光谱分析。主沟结合剂甲基绿被低浓度的两种肽置换，而次沟结合剂Hoechts和嵌入染料溴化乙锭仅在高浓度的肽置换。加入增加量的肽并进行荧光光谱。主沟结合剂甲基绿被低浓度的两种肽置换，而次沟结合剂Hoechts和嵌入染料溴化乙锭仅在高浓度的肽置换。加入增加量的肽并进行荧光光谱。主沟结合剂甲基绿被低浓度的两种肽置换，而次沟结合剂Hoechts和嵌入染料溴化乙锭仅在高浓度的肽置换。