Site-Specific Internal Motions in GB1 Protein Microcrystals Revealed by 3D (2)H-(13)C-(13)C Solid-State NMR Spectroscopy.
 

Site-Specific Internal Motions in GB1 Protein Microcrystals Revealed by 3D (2)H-(13)C-(13)C Solid-State NMR Spectroscopy.

Related Articles Site-Specific Internal Motions in GB1 Protein Microcrystals Revealed by 3D (2)H-(13)C-(13)C Solid-State NMR Spectroscopy.

J Am Chem Soc. 2016 Feb 5;

Authors: Shi X, Rienstra CM

Abstract
(2)H quadrupolar line shapes deliver rich information about protein dynamics. A newly designed 3D (2)H-(13)C-(13)Csolid-state NMR magic angle spinning (MAS) experiment is presented and demonstrated on the microcrystalline ?1 immunoglobulin binding domain of protein G (GB1). The implementation of (2)H-(13)C adiabatic rotor-echo-short-pulse-irradiation cross polarization (RESPIRATION CP) ensures the accuracy of the extracted line shapes and provides enhanced sensitivity relative to conventional CP methods. The 3D (2)H-(13)C-(13)C spectrum reveals 2H line shapes for 140 resolved aliphatic deuterium sites. Motional averaged (2)H quadrupolar parameters obtained from the line shape fitting identify side chain motions. Restricted side chain dynamics are observed for a number of polar residues including K13, D22, E27, K31, D36, N37, D46, D47, K50, and E56, which we attribute to the effects of salt bridges and hydrogen bonds. In contrast, we observe significantly enhanced side chain flexibility for Q2, K4, K10, E15, E19, N35, N40, and E42, due to solvent exposure and low packing density. T11, T16 and T17 side chains exhibit motions with larger amplitudes than other Thr residues due to solvent interactions. The side chains of L5, V54 and V29 are highly rigid because they are packed in the core of the protein.High correlations were demonstrated between GB1 side chain dynamics and its biological function. Large-amplitude side chain motions are observed for regions contacting and interacting with immunoglobulin G (IgG). In contrast, rigid side chains are primarily found for residues in the structural core of the protein that are absent from protein binding and interactions.


PMID: 26849428 [PubMed - as supplied by publisher]



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