TAILIEUCHUNG - Báo cáo khoa học: Crystal structures of the human SUMO-2 protein at 1.6 A and 1.2 A resolution

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 least fourSUMOproteins in humans, which are involved in protein trafficking and tar- geting. A truncated human SUMO-2 protein that contains residues 9–93 was expressed inEscherichia coliand crystal- lized in two different unit cells, with dimensions of a ¼b¼ A ˚ ,c¼ A ˚ and a¼b¼ A ˚ ,c¼ A ˚ , both belonging to the rhombohedral space groupR3. They diffractedX-rays A˚ A ˚ resolution, respectively | Eur. J. Biochem. 271 4114-4122 2004 FEBS 2004 doi Crystal structures of the human SUMO-2 protein at A and A resolution Implication on the functional differences of SUMO proteins Wen-Chen Huang1 2 Tzu-Ping Ko1 Steven Li3 and Andrew . Wang1 Institute of Biological Chemistry Academia Sinica Taipei Taiwan 2Institute of Biomedical Sciences National Sun Yat-Sen University Kaoshiung Taiwan 3Department of Biotechnology College of Life Sciences Kaoshiung Medical University Taiwan 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 Ả c A and a b Ả c A both belonging to the rhombohedral space group R3. They diffracted X-rays to A and A 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 and at A and A respectively. The peptide folding of SUMO-2 consists of a half-open b-barrel and two flanking a-helices with secondary structural elements arranged as bbabbab 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 crystalpacking analysis suggests a possible trimeric assembly of the SUMO-2 protein of which the biological significance remains to be determined. Keywords homology modeling molecular interactions protein modification surface charge .

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