Complex regulation of csgD promoter activity by global regulatory proteins
Complex regulation of csgD promoter activity by global regulatory proteins
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DOI：
10.1046/j.1365-2958.2003.03594.x
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发表时间：
2003-08-01
影响因子：
3.6
通讯作者：
Römling, U
中科院分区：
文献类型：
--
作者：
Gerstel, U;Park, C;Römling, U
鼠伤寒沙门氏菌饥饿诱导的 csgD 基因编码细胞外基质成分卷毛菌毛和纤维素的正转录调节因子。为了分析 csgD 启动子 (PcsgD) 反应的调控元件，进行了结合体外实验的遗传学研究。通过凝胶位移和 DNase I 足迹鉴定了转录调节因子 OmpR 的 6 个结合位点（D1 至 D6）。虽然 OmpR 是 PcsgD 表达所必需的，但 OmpR-P 与位于 D1 上游 -70.5 位的 D2 的结合被认为可以抑制 PcsgD 活性。响应微需氧条件，调节性和半组成性 PcsgD 的表达升高需要整合宿主因子 (IHF)。随后，在 PcsgD 的上游和下游鉴定了两个 IHF 结合位点。 IHF 与 OmpR-P 竞争在其上游位点 IHF1 上的结合，IHF1 与 D3-D6 重叠，从而调节对微需氧条件的响应。提出了一个涉及 IHF、H-NS 和 OmpR 的复杂调控网络，其中 csgD-csgBA 基因间区域中的核复合物组成会响应氧张力而改变。
The starvation-induced csgD gene of Salmonella typhimurium encodes for the positive transcriptional regulator of extracellular matrix components curli fimbriae and cellulose. To analyse regulatory elements of csgD promoter (PcsgD) response genetic studies combined with in vitro experiments were performed. Six binding sites (D1 to D6) for OmpR, a transcriptional regulator, were identified by gel shifts and DNase I footprints. While ompR is required for PcsgD expression, binding of OmpR-P to D2 centred immediately upstream of D1 at position -70.5 is proposed to repress PcsgD activity. The elevated expression of regulated and semiconstitutive PcsgD in response to microaerophilic conditions required integration host factor (IHF). Subsequently, two IHF-binding sites were identified up- and downstream of PcsgD. IHF competes with OmpR-P for binding at its upstream site IHF1, which overlaps with D3-D6 and thereby modulates the response to microaerophilic conditions. A complex regulatory network involving IHF, H-NS and OmpR is proposed whereby the nucleo-complex composition in the csgD-csgBA intergenic region is altered in response to oxygen tension.