Structure of the N-terminal domain of GRP94. Basis for ligand specificity and regulation.
GRP94, the endoplasmic reticulum (ER) paralog of the chaperone Hsp90, plays an essential role in the structural maturation or secretion of a subset of proteins destined for transport to the cell surface, such as the Toll-like receptors 2 and 4, and IgG, respectively. GRP94 differs from cytoplasmic Hsp90 by exhibiting very weak ATP binding and hydrolysis activity. GRP94 also binds selectively to a series of substituted adenosine analogs. The high resolution crystal structures at 1.75-2.1 A of the N-terminal and adjacent charged domains of GRP94 in complex with N-ethylcarboxamidoadenosine, radicicol, and 2-chlorodideoxyadenosine reveals a structural mechanism for ligand discrimination among hsp90 family members. The structures also identify a putative subdomain that may act as a ligand-responsive switch. The residues of the charged region fold into a disordered loop whose termini are ordered and continue the twisted beta sheet that forms the structural core of the N-domain. This continuation of the beta sheet past the charged domain suggests a structural basis for the association of the N-terminal and middle domains of the full-length chaperone.
Soldano
Karen L
KL
Departments of Biochemistry and Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Jivan
Arif
A
Nicchitta
Christopher V
CV
Gewirth
Daniel T
DT
D000241:Adenosine / Q000737:chemistry; D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D003593:Cytoplasm / Q000378:metabolism; D016048:Dideoxyadenosine / Q000031:analogs & derivatives* / Q000737:chemistry; D019281:Dimerization; D004285:Dogs; D004583:Electrons; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry*; D018841:HSP90 Heat-Shock Proteins / Q000737:chemistry; D007783:Lactones / Q000737:chemistry; D008024:Ligands; D018942:Macrolides; D008565:Membrane Proteins / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D007783:Lactones; D008024:Ligands; D018942:Macrolides; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; C018551:glucose-regulated proteins; C055504:2-chloro-2',3'-dideoxyadenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); D016048:Dideoxyadenosine; D005982:Glutathione Transferase; C035359:monorden; D000241:Adenosine