title: Crystal structure of the SENP1 mutant C603S-SUMO complex reveals the hydrolytic mechanism of SUMO-specific protease.
abstract: SUMO (small ubiquitin-related modifier)-specific proteases catalyse the maturation and de-conjugation processes of the sumoylation pathway and modulate various cellular responses including nuclear metabolism and cell cycle progression. The active-site cysteine residue is conserved among all known SUMO-specific proteases and is not substitutable by serine in the hydrolysis reactions demonstrated previously in yeast. We report here that the catalytic domain of human protease SENP1 (SUMO-specific protease 1) mutant SENP1C(C603S) carrying a mutation of cysteine to serine at the active site is inactive in maturation and de-conjugation reactions. To further understand the hydrolytic mechanism catalysed by SENP1, we have determined, at 2.8 A resolution (1 A = 0.1 nm), the X-ray structure of SENP1C(C603S)-SUMO-1 complex. A comparison of the structure of SENP2-SUMO-1 suggests strongly that SUMO-specific proteases require a self-conformational change prior to cleavage of peptide or isopeptide bond in the maturation and de-conjugation processes respectively. Moreover, analysis of the interface of SENP1 and SUMO-1 has led to the identification of four unique amino acids in SENP1 that facilitate the binding of SUMO-1. By means of an in vitro assay, we further demonstrate a novel function of SENP1 in hydrolysing the thioester linkage in E1-SUMO and E2-SUMO complexes. The results disclose a new mechanism of regulation of the sumoylation pathway by the SUMO-specific proteases.
authors.affiliation: Department of Biochemistry and Molecular Biotechnology Program, Centre for Protein Science and Crystallography, Faculty of Science, The Chinese University of Hong Kong, Shatin, Hong Kong.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Xu
authors.forename: So Fun
authors.initials: SF
authors.lastname: Chau
authors.forename: Kwok Ho
authors.initials: KH
authors.lastname: Lam
authors.forename: Ho Yin
authors.initials: HY
authors.lastname: Chan
authors.forename: Tzi Bun
authors.initials: TB
authors.lastname: Ng
authors.forename: Shannon W N
authors.initials: SW
authors.lastname: Au
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003546:Cysteine Endopeptidases; D010450:Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D025842:SUMO-1 Protein / Q000378:metabolism*
chemical_list: D025842:SUMO-1 Protein; D010450:Endopeptidases; C404512:SENP1 protein, human; D003546:Cysteine Endopeptidases; C501833:SENP2 protein, human