Shen Qing-Tao, Bai Xiao-Chen, Chang Lei-Fu, Wu Yi, Wang Hong-Wei, Sui Sen-Fang
Department of Biological Sciences and Biotechnology, State-Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China.
Proc Natl Acad Sci U S A. 2009 Mar 24;106(12):4858-63. doi: 10.1073/pnas.0811780106. Epub 2009 Mar 2.
In the periplasm of Escherichia coli, DegP (also known as HtrA), which has both chaperone-like and proteolytic activities, prevents the accumulation of toxic misfolded and unfolded polypeptides. In solution, upon binding to denatured proteins, DegP forms large cage-like structures. Here, we show that DegP forms a range of bowl-shaped structures, independent of substrate proteins, each with a 4-, 5-, or 6-fold symmetry and all with a DegP trimer as the structural unit, on lipid membranes. These membrane-bound DegP assemblies have the capacity to recruit and process substrates in the bowl chamber, and they exhibit higher proteolytic and lower chaperone-like activities than DegP in solution. Our findings imply that DegP might regulate its dual roles during protein quality control, depending on its assembly state in the narrow bacterial envelope.
在大肠杆菌的周质空间中，具有伴侣样活性和蛋白水解活性的DegP（也称为HtrA）可防止有毒的错误折叠和未折叠多肽的积累。在溶液中，DegP与变性蛋白结合后会形成大型笼状结构。在此，我们发现DegP在脂质膜上形成一系列碗状结构，这些结构独立于底物蛋白，每个结构具有四重、五重或六重对称性，且均以DegP三聚体作为结构单元。这些膜结合的DegP聚集体有能力在碗状腔室中招募和处理底物，并且它们比溶液中的DegP表现出更高的蛋白水解活性和更低的伴侣样活性。我们的研究结果表明，DegP可能在蛋白质质量控制过程中根据其在狭窄细菌包膜中的组装状态来调节其双重作用。
