Volume 08, No.5
September issue 2003
1. SPring-8の現状／PRESENT STATUS OF SPring-8
Call for the Beam Time Application for the Public Beamlines at SPring-8
Call for the Beam Time Application for Nanotechnology Experiments
The Experiments in the 11th Research Period (2003A) at the Public Beamlines of SPring-8
Interim Evaluation of Industrial Consortium Beamlines (BL16B2, BL16XU)
2. 最近の研究から／FROM LATEST RESEARCH
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、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
- 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
- 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
Meeting on the Results of FY 2002 Research Activities by the Synchrotron Radiation Research Group of the NanoTechnology Researchers Network Project, MEXT