Wollmann Petra, Zeth Kornelius
Max Planck Institute of Biochemistry, Department of Membrane Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany.
Max Planck Institute of Developmental Biology, Department of Protein Evolution, Spemannstrasse 35, D-72076 Tübingen, Germany.
J Mol Biol. 2007 Sep 28;372(4):927-941. doi: 10.1016/j.jmb.2007.06.039. Epub 2007 Jun 19.
An elegant network of signal transduction has evolved in the bacterial cell envelope to respond to environmental stress. It is initiated by sensing unfavourable and harmful changes in the periplasm. The stress signal is then transmitted by a controlled degradation of the transmembrane anti-sigma-factor RseA that leads to the activation of the alternative sigma factor sigma(E). The periplasmic protein RseB exerts a crucial role in modulating the stability of RseA. RseB from Escherichia coli has been crystallized and crystal structures were determined at 2.4 A and at 2.8 A resolution. The protein forms a homodimer, with the monomer composed of two domains. The large domain resembles an unclosed beta-barrel that is structurally remarkably similar to a protein family capable of binding the lipid anchor of lipoproteins. The small C-terminal domain, connected to the large domain by a partially unstructured loop, is responsible for interaction with RseA. On the basis of the structure of RseB, we suggest that it acts as a sensor of periplasmic stress with a dual functionality: it detects mislocalized lipoproteins and propagates the signal to induce the sigma(E)-response.
细菌细胞膜中已进化出一个精妙的信号转导网络来应对环境压力。它始于感知周质中不利和有害的变化。然后，应激信号通过跨膜抗σ因子RseA的受控降解进行传递，这会导致替代σ因子σ(E)的激活。周质蛋白RseB在调节RseA的稳定性方面发挥着关键作用。来自大肠杆菌的RseB已结晶，并在2.4埃和2.8埃分辨率下确定了晶体结构。该蛋白形成同源二聚体，单体由两个结构域组成。大结构域类似于一个未封闭的β桶，在结构上与能够结合脂蛋白脂质锚的蛋白质家族非常相似。小的C末端结构域通过一个部分无结构的环与大结构域相连，负责与RseA相互作用。基于RseB的结构，我们认为它作为周质应激的传感器具有双重功能：它检测错误定位的脂蛋白并传递信号以诱导σ(E)反应。
