The structural basis for promoter -35 element recognition by the group IV sigma factors.
The structural basis for promoter -35 element recognition by the group IV sigma factors.
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DOI：
10.1371/journal.pbio.0040269
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发表时间：
2006-09
期刊：
影响因子：
9.8
通讯作者：
Darst, Seth A
中科院分区：
文献类型：
--
作者：
Lane, William J;Darst, Seth A
细菌转录起始的控制取决于一个主要的σ因子的内务功能，以及替代σ因子控制的规则，以响应环境压力。最大和最多样化的可选σ因子亚群，即IV组胞质外功能σ因子，指导调控多种反应的基因转录，包括包膜应激和发病机制。我们确定了IV族σ因子Escherichia coli σ e4的- 35元素识别域的2.3-Å分辨率晶体结构，并与其一致的- 35元素GGAACTT结合。尽管初级因子和IV族σ因子具有相似的功能和二级结构，但它们通过不同的机制识别它们的−35元素。σE−35元素的保守序列元素诱导出AA/TT-tract DNA的几何特征，包括刚性、直的双螺旋轴和狭窄的小槽。因此，GGAACTT基序中间高度保守的AA对于σ e4识别−35元素至关重要，尽管这些DNA碱基没有直接的蛋白质- DNA相互作用。这些σ e 4/−35元素识别原理可以广泛应用于其他IV类σ因子。大肠杆菌IV群σ因子与DNA结合的晶体结构确定了依赖于DNA一致序列刚性构象的独特相互作用机制。
The control of bacterial transcription initiation depends on a primary σ factor for housekeeping functions, as well as alternative σ factors that control regulons in response to environmental stresses. The largest and most diverse subgroup of alternative σ factors, the group IV extracytoplasmic function σ factors, directs the transcription of genes that regulate a wide variety of responses, including envelope stress and pathogenesis. We determined the 2.3-Å resolution crystal structure of the −35 element recognition domain of a group IV σ factor, Escherichia coli σE 4, bound to its consensus −35 element, GGAACTT. Despite similar function and secondary structure, the primary and group IV σ factors recognize their −35 elements using distinct mechanisms. Conserved sequence elements of the σE −35 element induce a DNA geometry characteristic of AA/TT-tract DNA, including a rigid, straight double-helical axis and a narrow minor groove. For this reason, the highly conserved AA in the middle of the GGAACTT motif is essential for −35 element recognition by σE 4, despite the absence of direct protein–DNA interactions with these DNA bases. These principles of σE 4/−35 element recognition can be applied to a wide range of other group IV σ factors. A crystal structure of E. coli Group IV σ factor bound to DNA identifies a distinct mechanism of interaction reliant on the rigid conformation of the DNA consensus sequence.