title: Bowl-shaped oligomeric structures on membranes as DegP's new functional forms in protein quality control.
abstract: 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.
authors.affiliation: Department of Biological Sciences and Biotechnology, State-Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China.
authors.forename: Qing-Tao
authors.initials: QT
authors.lastname: Shen
authors.forename: Xiao-Chen
authors.initials: XC
authors.lastname: Bai
authors.forename: Lei-Fu
authors.initials: LF
authors.lastname: Chang
authors.forename: Yi
authors.initials: Y
authors.lastname: Wu
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Wang
authors.forename: Sen-Fang
authors.initials: SF
authors.lastname: Sui
mesh_terms: 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
chemical_list: D006360:Heat-Shock Proteins; D008055:Lipids; D018832:Molecular Chaperones; D033903:Periplasmic Proteins; C061682:DegP protease; D012697:Serine Endopeptidases