Dataset Information

Ultrafast Dynamics of Water-Protein Coupled Motions around the Surface of Eye Crystallin.

ABSTRACT: Water dynamics on the protein surface mediate both protein structure and function. However, many questions remain about the role of the protein hydration layers in protein fluctuations and how the dynamics of these layers relate to specific protein properties. The fish eye lens protein ?M7-crystallin (?M7) is found in vivo at extremely high concentrations nearing the packing limit, corresponding to only a few water layers between adjacent proteins. In this study, we conducted a site-specific probing of hydration water motions and side-chain dynamics at nine selected sites around the surface of ?M7 using a tryptophan scan with femtosecond spectroscopy and NMR nuclear spin relaxation (NSR). We observed correlated fluctuations between hydration water and protein side chains on the time scales of a few picoseconds and hundreds of picoseconds, corresponding to local reorientations and network restructuring, respectively. These motions are heterogeneous over the protein surface and relate to the various steric and chemical properties of the local protein environment. Overall, we found that ?M7 has relatively slower water dynamics within the hydration shell than a similar ?-sheet protein, which may contribute to the high packing limit of this unique protein.

SUBMITTER: Houston P

PROVIDER: S-EPMC7261499 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Ultrafast Dynamics of Water-Protein Coupled Motions around the Surface of Eye Crystallin.

Houston Patrick P Macro Nicolas N Kang Minhee M Chen Long L Yang Jin J Wang Lijuan L Wu Zhengrong Z Zhong Dongping D

Journal of the American Chemical Society 20200211 8

Water dynamics on the protein surface mediate both protein structure and function. However, many questions remain about the role of the protein hydration layers in protein fluctuations and how the dynamics of these layers relate to specific protein properties. The fish eye lens protein γM7-crystallin (γM7) is found in vivo at extremely high concentrations nearing the packing limit, corresponding to only a few water layers between adjacent proteins. In this study, we conducted a site-specific pro ...[more]

PMID: 31991083

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Project description:Lipid membranes are more than just barriers between cell compartments; they provide molecular environments with a finely tuned balance between hydrophilic and hydrophobic interactions that enable proteins to dynamically fold and self-assemble to regulate biological function. Characterizing dynamics at the lipid-water interface is essential to understanding molecular complexities from the thermodynamics of liquid-liquid phase separation down to picosecond-scale reorganization of interfacial hydrogen-bond networks.Ultrafast vibrational spectroscopy, including two-dimensional infrared (2D IR) and vibrational sum-frequency generation (VSFG) spectroscopies, is a powerful tool to examine picosecond interfacial dynamics. Two-dimensional IR spectroscopy provides a bond-centered view of dynamics with subpicosecond time resolutions, as vibrational frequencies are highly sensitive to the local environment. Recently, 2D IR spectroscopy has been applied to carbonyl and phosphate vibrations intrinsically located at the lipid-water interface. Interface-specific VSFG spectroscopy probes the water vibrational modes directly, accessing H-bond strength and water organization at lipid headgroup positions. Signals in VSFG arise from the interfacial dipole contributions, directly probing headgroup ordering and water orientation to provide a structural view of the interface.In this Account we discuss novel applications of ultrafast spectroscopy to lipid membranes, a field that has experienced significant growth over the past decade. In particular, ultrafast experiments now offer a molecular perspective on increasingly complex membranes. The powerful combination of ultrafast, interface-selective spectroscopy and simulations opens up new routes to understanding multicomponent membranes and their function. This Account highlights key prevailing views that have emerged from recent experiments: (1) Water dynamics at the lipid-water interface are slow compared to those of bulk water as a result of disrupted H-bond networks near the headgroups. (2) Peptides, ions, osmolytes, and cosolvents perturb interfacial dynamics, indicating that dynamics at the interface are affected by bulk solvent dynamics and vice versa. (3) The interfacial environment is generally dictated by the headgroup structure and orientation, but hydrophobic interactions within the acyl chains also modulate interfacial dynamics. Ultrafast spectroscopy has been essential to characterizing the biophysical chemistry of the lipid-water interface; however, challenges remain in interpreting congested spectra as well as designing appropriate model systems to capture the complexity of a membrane environment.

Dataset Information

Ultrafast Dynamics of Water-Protein Coupled Motions around the Surface of Eye Crystallin.

Publications

Ultrafast Dynamics of Water-Protein Coupled Motions around the Surface of Eye Crystallin.

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