Angelini Sandra, Deitermann Sandra, Koch Hans-Georg
Institute for Biochemistry & Molecular Biology, University Freiburg, Hermann-Herder-Strasse 7, 79104 Freiburg, Germany.
EMBO Rep. 2005 May;6(5):476-81. doi: 10.1038/sj.embor.7400385.
Co-translational membrane targeting of proteins by the bacterial signal-recognition particle (SRP) requires the specific interaction of the SRP-ribosome nascent chain complex with FtsY, the bacterial SRP receptor (SR). FtsY is homologous to the SRalpha-subunit of the eukaryotic SR, which is tethered to the endoplasmic-reticulum membrane by its interaction with the integral SRbeta-subunit. In contrast to SRalpha, FtsY is partly membrane associated and partly located in the cytosol. However, the mechanisms by which FtsY associates with the membrane are unclear. No gene encoding an SRbeta homologue has been found in bacterial genomes, and the presence of an FtsY-specific membrane receptor has not been shown so far. We now provide evidence for the direct interaction between FtsY and the SecY translocon. This interaction offers an explanation of how the bacterial SRP cycle is regulated in response to available translocation channels.
细菌信号识别颗粒（SRP）对蛋白质进行共翻译膜靶向需要SRP-核糖体新生链复合物与细菌SRP受体（SR）FtsY发生特异性相互作用。FtsY与真核生物SR的SRα亚基同源，后者通过与整合的SRβ亚基相互作用而锚定在内质网膜上。与SRα不同，FtsY部分与膜相关，部分位于胞质溶胶中。然而，FtsY与膜结合的机制尚不清楚。在细菌基因组中未发现编码SRβ同源物的基因，并且迄今为止尚未证明存在FtsY特异性膜受体。我们现在提供了FtsY与SecY易位子之间直接相互作用的证据。这种相互作用解释了细菌SRP循环如何响应可用的易位通道进行调节。
