Chlamydial histone-DNA interactions are disrupted by a metabolite in the methylerythritol phosphate pathway of isoprenoid biosynthesis
Chlamydial histone-DNA interactions are disrupted by a metabolite in the methylerythritol phosphate pathway of isoprenoid biosynthesis
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DOI：
10.1073/pnas.0400754101
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发表时间：
2004-05-11
影响因子：
11.1
通讯作者：
Hackstadt, T
中科院分区：
文献类型：
--
作者：
Grieshaber, NA;Fischer, ER;Hackstadt, T
衣原体发育周期的特点是细胞内的复制形式，称为网状体，和细胞外的形式，称为初级体。初级体的特点是染色质浓缩，由组蛋白h1样蛋白Hc1维持。随着衣原体转录变得活跃，初级体向网状体的分化伴随着染色质的分散，尽管Hc1从DNA释放的机制尚不清楚。类核的解离需要衣原体转录和翻译，而Hc1的损失可以忽略不计。因此，设计了一种遗传筛选来鉴定衣原体基因，使大肠杆菌免受Hc1过表达的致命影响。CT804是一个与ispE同源的基因，编码类异戊二烯生物合成非甲戊酸甲基赤藓糖醇磷酸（MEP）途径的中间酶。共表达CT804和Hc1的大肠杆菌生长正常，尽管它们表达Hc1的水平相当于表达ho的亲本对照的浓缩染色质。fosmidomycin抑制MEP通路可消除表达hc1的大肠杆菌的IspE拯救。来自表达IspE的细菌的脱蛋白提取物导致纯化的衣原体类核扩散，这表明衣原体组蛋白- dna相互作用被MEP途径中的一个小代谢物破坏，而不是由IspE的直接作用。通过MEP途径的部分重建，我们确定2- c -甲基赤藓糖醇2,4-环二磷酸将Hc1从衣原体染色质中解离。这些结果表明，衣原体组蛋白与dna的相互作用在萌发时被类异戊二烯生物合成MEP途径中的一个小代谢物破坏。
The chlamydial developmental cycle is characterized by an intracellular replicative form, termed the reticulate body, and an extracellular form called the elementary body. Elementary bodies are characterized by a condensed chromatin, which is maintained by a histone H1-like protein, Hc1. Differentiation of elementary bodies to reticulate bodies is accompanied by dispersal of the chromatin as chlamydiae become transcriptionally active, although the mechanisms of Hc1 release from DNA have remained unknown. Dissociation of the nucleoid requires chlamydial transcription and translation with negligible loss of Hc1. A genetic screen was therefore designed to identify chlamydial genes rescuing Escherichia coli from the lethal effects of Hc1 overexpression. CT804, a gene homologous to ispE, which encodes an intermediate enzyme of the non-mevalonate methylerythritol phosphate (MEP) pathway of isoprenoid biosynthesis, was selected. E. coli coexpressing CT804 and Hc1 grew normally, although they expressed Hc1 to a level equivalent to that which condensed the chromatin of parent HO-expressing controls. Inhibition of the MEP pathway with fosmidomycin abolished IspE rescue of Hc1-expressing E. coli. Deproteinated extract from IspE-expressing bacteria caused dispersal of purified chlamydial nucleoids, suggesting that chlamydial histone-DNA interactions are disrupted by a small metabolite within the MEP pathway rather than by direct action of IspE. By partial reconstruction of the MEP pathway, we determined that 2-C-methylerythritol 2,4-cyclodiphosphate dissociated Hc1 from chlamydial chromatin. These results suggest that chlamydial histone-DNA interactions are disrupted upon germination by a small metabolite in the MEP pathway of isoprenoid biosynthesis.