Crystal structures of the human SUMO-2 protein at 1.6 Å and 1.2 Å resolution: Implication on the functional differences of SUMO proteins

Wen Chen Huang, Tzu Ping Ko, Steven S.L. Li, Andrew H.J. Wang

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)

Abstract

The SUMO proteins are a class of small ubiquitin-like modifiers. SUMO is attached to a specific lysine side chain on the target protein via an isopeptide bond with its C-terminal glycine. There are at least four SUMO proteins in humans, which are involved in protein trafficking and targeting. A truncated human SUMO-2 protein that contains residues 9-93 was expressed in Escherichia coli and crystallized in two different unit cells, with dimensions of a = b = 75.25 Å, c = 29.17 Å and a = b = 74.96 Å, c = 33.23 Å, both belonging to the rhpmbohedral space group R3. They diffracted X-rays to 1.6 Å and 1.2 Å resolution, respectively. The structures were determined by molecular replacement using the yeast SMT3 protein as a search model. Subsequent refinements yielded R/Rfree values of 0.169/0.190 and 0.119/ 0.185, at 1.6 Å and 1.2 Å, respectively. The peptide folding of SUMO-2 consists of a half-open β-barrel and two flanking α-helices with secondary structural elements arranged as ββαββαβ in the sequence, identical to those of ubiquitin, SMT3 and SUMO-1. Comparison of SUMO-2 with SUMO-1 showed a surface region near the C terminus with significantly different charge distributions. This may explain their distinct intracellular locations. In addition, crystal-packing analysis suggests a possible trimeric assembly of the SUMO-2 protein, of which the biological significance remains to be determined.

Original languageEnglish
Pages (from-to)4114-4122
Number of pages9
JournalEuropean Journal of Biochemistry
Volume271
Issue number20
DOIs
Publication statusPublished - Oct 2004
Externally publishedYes

Keywords

  • Homology modeling
  • Molecular interactions
  • Protein modification
  • Surface charge distributions
  • Synchrotron radiations

ASJC Scopus subject areas

  • Biochemistry

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