1a5r
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STRUCTURE DETERMINATION OF THE SMALL UBIQUITIN-RELATED MODIFIER SUMO-1, NMR, 10 STRUCTURES
OverviewOverview
The recently discovered small ubiquitin-related modifier SUMO-1 belongs to, the growing family of ubiquitin-related proteins involved in, postranslational protein modification. Unlike ubiquitin, SUMO-1 does not, appear to target proteins for degradation but seems to be involved in the, modulation of protein-protein interactions. Independent studies, demonstrate an essential function of SUMO-1 in the regulation of, nucleo-cytoplasmic transport, and suggest a role in cell-cycle regulation, and apoptosis. Here, we present the first three-dimensional structure of, SUMO-1 solved by NMR. Although having only 18% amino acid sequence, identity with ubiquitin, the overall structure closely resembles that of, ubiquitin, featuring the betabetaalphabetabetaalphabeta fold of the, ubiquitin protein family. In addition, the position of the two C-terminal, Gly residues required for isopeptide bond formation is conserved between, ubiquitin and SUMO-1. The most prominent feature of SUMO-1 is a long and, highly flexible N terminus, which protrudes from the core of the protein, and which is absent in ubiquitin. Furthermore, ubiquitin Lys48, required, to generate ubiquitin polymers, is substituted in SUMO-1 by Gln69 at the, same position, which provides an explanation of why SUMO-1 has not been, observed to form polymers. Moreover, the hydrophobic core of SUMO-1 and, ubiquitin is maintained by conserved hydrophobic residues, whereas the, overall charge topology of SUMO-1 and ubiquitin differs significantly, suggesting specific modifying enzymes and target proteins for both, proteins.
About this StructureAbout this Structure
1A5R is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
Structure determination of the small ubiquitin-related modifier SUMO-1., Bayer P, Arndt A, Metzger S, Mahajan R, Melchior F, Jaenicke R, Becker J, J Mol Biol. 1998 Jul 10;280(2):275-86. PMID:9654451
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