Karamanou Spyridoula, Bariami Vassiliki, Papanikou Efrosyni, Kalodimos Charalampos G, Economou Anastassios
Institute of Molecular Biology and Biotechnology-FoRTH, PO Box 1385, Iraklio, Crete, Greece.
Mol Microbiol. 2008 Oct;70(2):311-22. doi: 10.1111/j.1365-2958.2008.06402.x. Epub 2008 Aug 22.
Bacterial protein secretion is catalysed by the SecYEG protein-conducting channel complexed with the SecA ATPase motor. To gain insight into the SecA-SecYEG interaction we used peptide arrays, thermodynamic quantification, mutagenesis and functional assays. Our data reveal that: (i) SecA binds with low affinity on several, peripheral, exposed SecYEG sites. This largely electrostatic association is modulated by temperature and nucleotides. (ii) Binding sites cluster in five major binding 'regions': three that are exclusively cytoplasmic and two that reach the periplasm. (iii) Both the N-terminal and c-terminal regions of SecA participate in binding interactions and share some sites. (iv) Several of these sites are essential for translocase catalysis. Our data provide residue-level dissection of the SecYEG-SecA interaction. Two models of assembly of SecA on dimeric SecYEG are discussed.
细菌蛋白质分泌由与SecA ATP酶马达复合的SecYEG蛋白质传导通道催化。为深入了解SecA与SecYEG的相互作用，我们使用了肽阵列、热力学定量、诱变和功能测定。我们的数据表明：（i）SecA以低亲和力结合在几个外周暴露的SecYEG位点上。这种主要为静电作用的结合受温度和核苷酸调节。（ii）结合位点聚集在五个主要结合“区域”：三个完全位于细胞质中，两个延伸到周质。（iii）SecA的N端和C端区域都参与结合相互作用并共享一些位点。（iv）这些位点中的几个对转位酶催化至关重要。我们的数据提供了SecYEG与SecA相互作用的残基水平剖析。讨论了SecA在二聚体SecYEG上组装的两种模型。
