title: Structure and reactivity of an asymmetric complex between HslV and I-domain deleted HslU, a prokaryotic homolog of the eukaryotic proteasome.
abstract: In the prokaryotic homolog of the eukaryotic proteasome, HslUV, the "double donut" HslV protease is allosterically activated by HslU, an AAA protein of the Clp/Hsp100 family consisting of three (amino-terminal, carboxy-terminal, and intermediate) domains. The intermediate domains of HslU, which extend like tentacles from the hexameric ring formed by the amino-terminal and carboxy-terminal domains, have been deleted; an asymmetric HslU(DeltaI)(6)HslV(12) complex has been crystallized; and the structure has been solved to 2.5A resolution, revealing an assembly in which a HslU(DeltaI) hexamer binds one end of the HslV dodecamer. The conformation of the protomers of the HslU(DeltaI)-complexed HslV hexamer is similar to that in the symmetric wild-type HslUV complex, while the protomer conformation of the uncomplexed HslV hexamer is similar to that of HslV alone. Reaction in the crystals with a vinyl sulfone inhibitor reveals that the HslU(DeltaI)-complexed HslV hexamer is active, while the uncomplexed HslV hexamer is inactive. These results confirm that HslV can be activated by binding of a hexameric HslU(DeltaI)(6) ring lacking the I domains, that activation is effected through a conformational change in HslV rather than through alteration of the size of the entry channel into the protease catalytic cavity, and that the two HslV(6) rings in the protease dodecamer are activated independently rather than cooperatively.
authors.affiliation: Department of Structural Biology, Stanford University School of Medicine, Sherman Fairchild Building, Stanford, CA 94305, USA.
authors.forename: Ae-Ran
authors.initials: AR
authors.lastname: Kwon
authors.forename: Benedikt M
authors.initials: BM
authors.lastname: Kessler
authors.forename: Herman S
authors.initials: HS
authors.lastname: Overkleeft
authors.forename: David B
authors.initials: DB
authors.lastname: McKay
mesh_terms: D049069:ATP-Dependent Proteases; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D006193:Haemophilus influenzae / Q000201:enzymology; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D046911:Macromolecular Substances; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000737:chemistry*; D009842:Oligopeptides / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D012697:Serine Endopeptidases / Q000737:chemistry*; D013450:Sulfones / Q000494:pharmacology
chemical_list: D006360:Heat-Shock Proteins; D046911:Macromolecular Substances; D009097:Multienzyme Complexes; D009842:Oligopeptides; D011480:Protease Inhibitors; D011994:Recombinant Proteins; D013450:Sulfones; C423405:tri-leucine-vinyl-sulfone; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex