期刊
JOURNAL OF BIOLOGICAL CHEMISTRY
卷 285, 期 14, 页码 10671-10677出版社
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M109.082925
关键词
-
资金
- Ministry of Education, Culture, Sports, Science and Technology
- Japanese Science and Technology Cooperation, Japan
We have used pulsed electron-electron double resonance (PELDOR) spectroscopy to measure the distance between spin labels at Cys(133) of the regulatory region of TnI (TnI133) and a native or genetically substituted cysteine of TnC (TnC44, TnC61, or TnC98). In the +Ca2+ state, the TnC44-TnI133-T distance was 42 angstrom, with a narrow distribution (half-width of 9 angstrom), suggesting that the regulatory region binds the N-lobe of TnC. Distances for TnC61-TnI133 and TnC98-TnI133 were also determined to be 38 angstrom (width of 12 angstrom) and 22 angstrom (width of 3.4 angstrom), respectively. These values were all consistent with recently published crystal structure (Vinogradova, M. V., Stone, D. B., Malanina, G. G., Karatzaferi, C., Cooke, R., Mendelson, R. A., and Fletterick, R. J. (2005) Proc. Natl Acad. Sci. U. S. A. 102, 50385043). Similar distances were obtained with the same spin pairs on a reconstituted thin filament in the +Ca2+ state. In the -Ca2+ state, the distances displayed broad distributions, suggesting that the regulatory region of TnI was physically released from the N-lobe of TnC and consequently fluctuated over a variety of distances on a large scale (20-80 angstrom). The interspin distance appeared longer on the filament than on troponin alone, consistent with the ability of the region to bind actin. These results support a concept that the regulatory region of TnI, as a molecular switch, binds to the exposed hydrophobic patch of TnC and traps the inhibitory region of TnI away from actin in Ca2+ activation of muscle.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据