生物大分子结构模拟与精确测定:The Three-Dimensional Structure and X-Ray Sequence Reveal that Trichomaglin...

  • 关键字: Trichomaglin Is a Novel S-like Ribonuclease 发布者:J.-H. Gan, Z.-X. Xia* 发布时间:2009-03-02 21:03:04 点击数: 3815次

Structure, 2004, 12, 1015-1025
The Three-Dimensional Structure and X-Ray Sequence Reveal that Trichomaglin Is a Novel S-like Ribonuclease
J.-H. Gan, L. Yu, J. Wu, H. Xu, J. S. Choudhary, W. P. Blackstock, W.-Y. Liu, Z.-X. Xia*
1State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China. 2Cell Map Project, GlaxoSmithKline, Stevenage, United Kingdom 3State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
Abstract: Trichomaglin is a protein isolated from root tuber of the plant Maganlin (Trichosanthes Lepiniate, Cucurbitaceae). The crystal structure of trichomaglin has been determined by multiple-isomorphous replacement and refined at 2.2 Å resolution. The X-ray sequence was established, based on electron density combined with the experimentally determined N-terminal sequence, and the sequence information derived from mass spectroscopic analysis. X-ray sequence-based homolog search and the three-dimensional structure reveal that trichomaglin is a novel S-like RNase, which was confirmed by biological assay. Trichomaglin molecule contains an additional β sheet in the HVb region, compared with the known plant RNase structures. Fourteen cystein residues form seven disulfide bridges, more than those in the other known structures of S- and S-like RNases. His43 and His105 are expected to be the catalytic acid and base, respectively. Four hydrosulfate ions are bound in the active site pocket, three of them mimicking the substrate binding sites.