1uch

From Proteopedia

Revision as of 17:26, 12 November 2007

DEUBIQUITINATING ENZYME UCH-L3 (HUMAN) AT 1.8 ANGSTROM RESOLUTION

Overview

Ubiquitin C-terminal hydrolases catalyze the removal of adducts from the, C-terminus of ubiquitin. We have determined the crystal structure of the, recombinant human Ubiquitin C-terminal Hydrolase (UCH-L3) by X-ray, crystallography at 1.8 A resolution. The structure is comprised of a, central antiparallel beta-sheet flanked on both sides by alpha-helices., The beta-sheet and one of the helices resemble the well-known papain-like, cysteine proteases, with the greatest similarity to cathepsin B. This, similarity includes the UCH-L3 active site catalytic triad of Cys95, His169 and Asp184, and the oxyanion hole residue Gln89. Papain and UCH-L3, differ, however, in strand and helix connectivity, which in the UCH-L3, structure includes a disordered 20 residue loop (residues 147-166) that is, positioned over the active site and may function in the definition of, substrate specificity. Based upon analogy with inhibitor complexes of the, papain-like enzymes, we propose a model describing the binding of, ubiquitin to UCH-L3. The UCH-L3 active site cleft appears to be masked in, the unliganded structure by two different segments of the enzyme (residues, 9-12 and 90-94), thus implying a conformational change upon substrate, binding and suggesting a mechanism to limit non-specific hydrolysis.

About this Structure

1UCH is a Single protein structure of sequence from Homo sapiens. Active as Ubiquitin thiolesterase, with EC number 3.1.2.15 Structure known Active Site: CAT. Full crystallographic information is available from OCA.

Reference

Crystal structure of a deubiquitinating enzyme (human UCH-L3) at 1.8 A resolution., Johnston SC, Larsen CN, Cook WJ, Wilkinson KD, Hill CP, EMBO J. 1997 Jul 1;16(13):3787-96. PMID:9233788

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