Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, 92697-4560.
Protein Sci. 2019 Jun;28(6):984-989. doi: 10.1002/pro.3619. Epub 2019 May 1.
Much is known about the structure, function, and stability of the SecA motor ATPase that powers the secretion of periplasmic proteins across the inner membrane of Escherichia coli. Most studies of SecA are carried out in buffered sodium or potassium chloride salt solutions. However, the principal intracellular salt of E. coli is potassium glutamate (KGlu), which is known to stabilize folded proteins and protein-nucleic acid complexes. Here we report that KGlu stabilizes SecA, including its dimeric state, and increases its ATPase activity, suggesting that SecA is likely fully folded, stable, and active in vivo at 37°C. Furthermore, KGlu also stabilizes a precursor form of the secreted maltose-binding protein.
关于驱动周质蛋白穿过大肠杆菌内膜分泌的 SecA 马达 ATP 酶的结构、功能和稳定性，人们已经了解很多。大多数 SecA 的研究都是在缓冲的氯化钠或氯化钾盐溶液中进行的。然而，大肠杆菌的主要细胞内盐是谷氨酸钾（KGlu），它已知可以稳定折叠的蛋白质和蛋白质-核酸复合物。在这里，我们报告说 KGlu 稳定了 SecA，包括其二聚体状态，并增加了其 ATP 酶活性，这表明 SecA 在 37°C 下可能完全折叠、稳定且在体内具有活性。此外，KGlu 还稳定了分泌型麦芽糖结合蛋白的前体形式。
