Solution structure of the ubiquitin-binding domain in Swa2p from Saccharomyces cerevisiae.

Chim N, Gall WE, Xiao J, Harris MP, Graham TR, Krezel AM
Proteins. 2004 54 (4): 784-93

PMID: 14997574 · DOI:10.1002/prot.10636

The SWA2/AUX1 gene has been proposed to encode the Saccharomyces cerevisiae ortholog of mammalian auxilin. Swa2p is required for clathrin assembly/dissassembly in vivo, thereby implicating it in intracellular protein and lipid trafficking. While investigating the 287-residue N-terminal region of Swa2p, we found a single stably folded domain between residues 140 and 180. Using binding assays and structural analysis, we established this to be a ubiquitin-associated (UBA) domain, unidentified by bioinformatics of the yeast genome. We determined the solution structure of this Swa2p domain and found a characteristic three-helix UBA fold. Comparisons of structures of known UBA folds reveal that the position of the third helix is quite variable. This helix in Swa2p UBA contains a bulkier tyrosine in place of smaller residues found in other UBAs and cannot pack as close to the second helix. The molecular surface of Swa2p UBA has a mostly negative potential, with a single hydrophobic surface patch found also in the UBA domains of human protein, HHR23A. The presence of a UBA domain implicates Swa2p in novel roles involving ubiquitin and ubiquitinated substrates. We propose that Swa2p is a multifunctional protein capable of recognizing several proteins through its protein-protein recognition domains.

Copyright 2004 Wiley-Liss, Inc.

MeSH Terms (17)

Amino Acid Sequence Carrier Proteins Conserved Sequence Models, Molecular Molecular Sequence Data Nuclear Magnetic Resonance, Biomolecular Phosphoproteins Protein Binding Protein Folding Protein Structure, Secondary Protein Structure, Tertiary Saccharomyces cerevisiae Saccharomyces cerevisiae Proteins Solutions Static Electricity Ubiquitin Vesicular Transport Proteins

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