Bowl-shaped oligomeric structures on membranes as DegP's new functional forms in protein quality control.
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.
Shen
Qing-Tao
QT
Department of Biological Sciences and Biotechnology, State-Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China.
Bai
Xiao-Chen
XC
Chang
Lei-Fu
LF
Wu
Yi
Y
Wang
Hong-Wei
HW
Sui
Sen-Fang
SF
D002462:Cell Membrane / Q000201:enzymology* / Q000648:ultrastructure; D004926:Escherichia coli / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000648:ultrastructure; D008055:Lipids / Q000737:chemistry; D018832:Molecular Chaperones / Q000378:metabolism; D033903:Periplasmic Proteins / Q000737:chemistry* / Q000648:ultrastructure; D011499:Protein Processing, Post-Translational; D020836:Protein Structure, Quaternary; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000648:ultrastructure; D013379:Substrate Specificity
D006360:Heat-Shock Proteins; D008055:Lipids; D018832:Molecular Chaperones; D033903:Periplasmic Proteins; C061682:DegP protease; D012697:Serine Endopeptidases