Solution structure of the ubiquitin-binding domain in Swa2p from Saccharomyces cerevisiae.
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.
Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37232, USA.
Nicholas
N
Chim
Walter E
WE
Gall
Jing
J
Xiao
Mark P
MP
Harris
Todd R
TR
Graham
Andrzej M
AM
Krezel
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D017124:Conserved Sequence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism*; D012996:Solutions / Q000737:chemistry; D055672:Static Electricity; D025801:Ubiquitin / Q000378:metabolism*; D033921:Vesicular Transport Proteins
D002352:Carrier Proteins; D010750:Phosphoproteins; C419865:SWA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D012996:Solutions; D025801:Ubiquitin; D033921:Vesicular Transport Proteins