1uel

From Proteopedia

Revision as of 12:31, 20 March 2008

Solution structure of ubiquitin-like domain of hHR23B complexed with ubiquitin-interacting motif of proteasome subunit S5a

Overview

Ubiquitination, a modification in which single or multiple ubiquitin molecules are attached to a protein, serves signaling functions that control several cellular processes. The ubiquitination signal is recognized by downstream effectors, many of which carry a ubiquitin-interacting motif (UIM). Such interactions can be modulated by regulators carrying a ubiquitin-like (UbL) domain, which binds UIM by mimicking ubiquitination. Of them, HR23B regulates the proteasomal targeting of ubiquitinated substrates, DNA repair factors, and other proteins. Here we report the structure of the UIM of the proteasome subunit S5a bound to the UbL domain of HR23B. The UbL domain presents one hydrophobic and two polar contact sites for interaction with UIM. The residues in these contact sites are well conserved in ubiquitin, but ubiquitin also presents a histidine at the interface. The pH-dependent protonation of this residue interferes with the access of ubiquitin to the UIM and the ubiquitin-associated domain (UBA), and its mutation to a smaller residue increases the affinity of ubiquitin for UIM.

About this Structure

1UEL is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.

Reference

Structure of the ubiquitin-interacting motif of S5a bound to the ubiquitin-like domain of HR23B., Fujiwara K, Tenno T, Sugasawa K, Jee JG, Ohki I, Kojima C, Tochio H, Hiroaki H, Hanaoka F, Shirakawa M, J Biol Chem. 2004 Feb 6;279(6):4760-7. Epub 2003 Oct 29. PMID:14585839

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