期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 107, 期 14, 页码 6270-6274出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0910246107
关键词
allostery; conformational dynamics; fluorescence correlation spectroscopy; molecular chaperones; chaperonins
资金
- National Institutes of Health [R01GM080515]
- Minerva Foundation
The molecular chaperone GroEL exists in at least two allosteric states, Tand R, that interconvert in an ATP-controlled manner. Thermodynamic analysis suggests that the T-state population becomes negligible with increasing ATP concentrations, in conflict with the requirement for conformational cycling, which is essential for the operation of molecular machines. To solve this conundrum, we performed fluorescence correlation spectroscopy on the single-ring version of GroEL, using a fluorescent switch recently built into its structure, which turns on, i.e., increases its fluorescence dramatically, when ATP is added. A series of correlation functions was measured as a function of ATP concentration and analyzed using singular-value decomposition. The analysis assigned the signal to two states whose dynamics clearly differ. Surprisingly, even at ATP saturation, similar to 50% of the molecules still populate the T state at any instance of time, indicating constant out-of-equilibrium cycling between T and R. Only upon addition of the cochaperonin GroES does the T-state population vanish. Our results suggest a model in which the T/R ratio is controlled by the rate of ADP release after hydrolysis, which can be determined accordingly.
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