1ofh: Difference between revisions

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.

1OFH is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Haemophilus_influenzae Haemophilus influenzae] with PO4, MG and ADP as [http://en.wikipedia.org/wiki/ligands ligands]. Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1OFH OCA].  

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