It is now widely recognized that dynamics are important to consider for understanding allosteric protein function. However, dynamics occur over a wide range of timescales, and how these different motions relate to one another is not well understood. Here, we report an NMR relaxation study of dynamics over multiple timescales at both backbone and side-chain sites upon an allosteric response to phosphorylation. The response regulator, Escherichia coli CheY, allosterically responds to phosphorylation with a change in dynamics on both the microsecond-to-millisecond (μs-ms) timescale and the picosecond-to- nanosecond (ps-ns) timescale. We observe an apparent decrease and redistribution of μs-ms dynamics upon phosphorylation (and accompanying Mg2 + saturation) of CheY. Additionally, methyl groups with the largest changes in ps-ns dynamics localize to the regions of conformational change measured by μs-ms dynamics. The limited spread of changes in ps-ns dynamics suggests a distinct relationship between motions on the μs-ms and ps-ns timescales in CheY. The allosteric mechanism utilized by CheY highlights the diversity of roles dynamics play in protein function.
Bibliographical noteFunding Information:
This work was supported by National Institutes of Health grant GM066009 (to A.L.L.), and additional support was provided to L.R.M. through National Institutes of Health training grant GM008570 .
- CPMG relaxation dispersion
- response regulator
- side-chain dynamics