Robson Alice, Carr Beatrice, Sessions Richard B, Collinson Ian
Department of Biochemistry, University of Bristol, University Walk, Bristol, UK.
FEBS Lett. 2009 Jan 5;583(1):207-12. doi: 10.1016/j.febslet.2008.12.003. Epub 2008 Dec 10.
A short helix in the centre of the SecY subunit serves as a 'plug' blocking the protein channel. This site must be vacated if the channel is to open and accommodate translocating protein. We have synthesised a peptide mimic of this plug, and show that it binds to E. coli SecYEG, identifying a distinct and peripheral binding site. We propose that during active translocation the plug moves to this second discrete site and chart its position. Deletion of the plug in SecY increases the stoichiometry of the peptide-SecYEG interaction by also exposing the location it occupies in the channel. Binding of the plug peptide to the channel is unaffected by SecA.
SecY亚基中心的一个短螺旋充当“塞子”，阻塞蛋白质通道。如果通道要打开并容纳正在转运的蛋白质，这个位点必须空出来。我们合成了这种塞子的肽模拟物，并表明它与大肠杆菌SecYEG结合，确定了一个独特的外周结合位点。我们提出，在主动转运过程中，塞子会移动到这个第二个离散位点并确定其位置。SecY中塞子的缺失也通过暴露它在通道中占据的位置增加了肽与SecYEG相互作用的化学计量。塞子肽与通道的结合不受SecA的影响。
