title: Characterization of the Grp94/OS-9 chaperone-lectin complex.
abstract: Grp94 is a macromolecular chaperone belonging to the hsp90 family and is the most abundant glycoprotein in the endoplasmic reticulum (ER) of mammals. In addition to its essential role in protein folding, Grp94 was proposed to participate in the ER-associated degradation quality control pathway by interacting with the lectin OS-9, a sensor for terminally misfolded proteins. To understand how OS-9 interacts with ER chaperone proteins, we mapped its interaction with Grp94. Glycosylation of the full-length Grp94 protein was essential for OS-9 binding, although deletion of the Grp94 N-terminal domain relieved this requirement suggesting that the effect was allosteric rather than direct. Although yeast OS-9 is composed of a well-established N-terminal mannose recognition homology lectin domain and a C-terminal dimerization domain, we find that the C-terminal domain of OS-9 in higher eukaryotes contains "mammalian-specific insets" that are specifically recognized by the middle and C-terminal domains of Grp94. Additionally, the Grp94 binding domain in OS-9 was found to be intrinsically disordered. The biochemical analysis of the interacting regions provides insight into the manner by which the two associate and it additionally hints at a plausible biological role for the Grp94/OS-9 complex.
authors.affiliation: Department of Structural Biology, University at Buffalo, 700 Ellicott Street, Buffalo, NY 14203, USA; Hauptman Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203, USA.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Seidler
authors.affiliation: Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, 766 Irving Aveenue, Syracuse, NY 13210, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Shinsky
authors.affiliation: Department of Microbiology and Immunology, Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Hong
authors.affiliation: Department of Microbiology and Immunology, Hollings Cancer Center, Medical University of South Carolina, 86 Jonathan Lucas Street, Charleston, SC 29425, USA.
authors.forename: Zihai
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, 766 Irving Aveenue, Syracuse, NY 13210, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Cosgrove
authors.affiliation: Department of Structural Biology, University at Buffalo, 700 Ellicott Street, Buffalo, NY 14203, USA; Hauptman Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203, USA. Electronic address: gewirth@hwi.buffalo.edu.
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Gewirth
mesh_terms: D000495:Allosteric Site; D000818:Animals; D002417:Cattle; D004285:Dogs; D004926:Escherichia coli / Q000378:metabolism; D006031:Glycosylation; D057809:HEK293 Cells; D006801:Humans; D037102:Lectins / Q000737:chemistry* / Q000502:physiology; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000502:physiology; D018832:Molecular Chaperones / Q000737:chemistry*; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000502:physiology; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D051381:Rats; D013816:Thermodynamics; D014461:Ultracentrifugation; D015003:Yeasts
chemical_list: D037102:Lectins; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; C098898:OS9 protein, human; C000594871:OS9 protein, rat; C053387:endoplasmin
keywords: ER-associated degradation; Grp94; Hsp90; chaperone; intrinsically disordered protein