Volume 08, No.5
September issue 2003
（財）高輝度光科学研究センター 副理事長、放射光研究所長 Director General of Synchrotron Radiation Research Laboratory, Vice President of JASRI
1. SPring-8の現状／PRESENT STATUS OF SPring-8
（財）高輝度光科学研究センター 所長室 計画調整グループ Planning and Coordination Section, Directorﾕs Office, JASRI
東京工業大学 応用セラミックス研究所 Materials and Structures Laboratory, Tokyo Institute of Technology
2. 最近の研究から／FROM LATEST RESEARCH
[1]国立循環器病センター研究所 心臓生理部 Department of Cardiac Physiology, National Cardiovascular Center Research Institute、[2]理化学研究所 播磨研究所 構造生物化学研究室 Laboratory of Structural Biochemistry, Riken Harima Institute
- Abstract
- Troponin (Tn) plays key roles in the Ca2+ regulation of skeletal and cardiac muscle contraction. It consists of three subunits (TnT, TnC and TnI), and, together with tropomyosin (Tm), is located on the actin filament. We have solved crystal structures of the core domains (relative molecular mass of 46kDa and 52kDa) of human cardiac Tn in the Ca2+-saturated form. The structures reveal that the core domain is further divided into structurally distinct sub-domains that are connected by flexible linkers, making the entire molecule highly flexible. The α-helical coiled-coil formed between TnT and TnI is integrated in a rigid and asymmetric structure (about 80Å long), the IT-arm, which bridges putative Tm-anchoring regions. The structures of Tn ternary complex imply that the Ca2+-binding to the regulatory site of TnC removes the C-terminal portion of TnI from actin/Tm, thereby alters the flexibility of Tn/Tm on the actin filament.
東京大学大学院 理学系研究科 Graduate School of Science, The University of Tokyo
- Abstract
- The archaeal/eukaryotic tyrosyl-tRNA synthetase (TyrRS)–tRNATyr pairs do not cross-react with their bacterial counterparts. This ‘orthogonal’ condition is essential for using the archaeal pair to expand the bacterial genetic code. We solved the 1.95 Å-resolution structure of an archaeal TyrRS–tRNATyr–L-tyrosine complex by using the X-ray diffraction data sets collected at the beamline BL41XU, SPring-8. This structure reveals that this archaeal TyrRS strictly recognizes the C1:G72 base pair, whereas the bacterial TyrRS recognizes the G1:C72 in a different manner using different residues. These diverse tRNA recognition modes form the basis for the orthogonality.
3. 研究会等報告／WORKSHOP AND COMMITTEE REPORT
（財）高輝度光科学研究センター 所長室 研究事務グループ Research Secretariat, Director’s Office, JASRI
姫路工業大学大学院 理学研究科 Graduate School and Faculty of Science, Himeji Institute of Technology
研究成果報告会 プログラム委員会 Program Committee, Meeting on the Results of Research Actirities
4. 談話室・ユーザー便り／OPEN HOUSE・A LETTER FROM SPring-8 USERS
（財）高輝度光科学研究センター 利用研究促進部門Ⅰ Materials Science Division, JASRI
