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Peptide and Protein Dynamics and Low-Temperature/DNP Magic Angle Spinning NMR.

ABSTRACT: In DNP MAS NMR experiments at ?80-110 K, the structurally important -13CH3 and -15NH3+ signals in MAS spectra of biological samples disappear due to the interference of the molecular motions with the 1H decoupling. Here we investigate the effect of these dynamic processes on the NMR line shapes and signal intensities in several typical systems: (1) microcrystalline APG, (2) membrane protein bR, (3) amyloid fibrils PI3-SH3, (4) monomeric alanine-CD3, and (5) the protonated and deuterated dipeptide N-Ac-VL over 78-300 K. In APG, the three-site hopping of the Ala-C? peak disappears completely at 112 K, concomitant with the attenuation of CP signals from other 13C's and 15N's. Similarly, the 15N signal from Ala-NH3+ disappears at ?173 K, concurrent with the attenuation in CP experiments of other 15N's as well as 13C's. In bR and PI3-SH3, the methyl groups are attenuated at ?95 K, while all other 13C's remain unaffected. However, both systems exhibit substantial losses of intensity at ?243 K. Finally, with spectra of Ala and N-Ac-VL, we show that it is possible to extract site specific dynamic data from the temperature dependence of the intensity losses. Furthermore, 2H labeling can assist with recovering the spectral intensity. Thus, our study provides insight into the dynamic behavior of biological systems over a wide range of temperatures, and serves as a guide to optimizing the sensitivity and resolution of structural data in low temperature DNP MAS NMR spectra.

SUBMITTER: Ni QZ

PROVIDER: S-EPMC5874497 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Peptide and Protein Dynamics and Low-Temperature/DNP Magic Angle Spinning NMR.

Ni Qing Zhe QZ Markhasin Evgeny E Can Thach V TV Corzilius Björn B Tan Kong Ooi KO Barnes Alexander B AB Daviso Eugenio E Su Yongchao Y Herzfeld Judith J Griffin Robert G RG

The journal of physical chemistry. B 20170510 19

In DNP MAS NMR experiments at ∼80-110 K, the structurally important -13CH3 and -15NH3+ signals in MAS spectra of biological samples disappear due to the interference of the molecular motions with the 1H decoupling. Here we investigate the effect of these dynamic processes on the NMR line shapes and signal intensities in several typical systems: (1) microcrystalline APG, (2) membrane protein bR, (3) amyloid fibrils PI3-SH3, (4) mon ...[more]

PMID: 28437077

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Project description:Solid-state NMR spectroscopy can be used to probe internal protein dynamics in the absence of the overall molecular tumbling. In this study, we report (15)N backbone dynamics in differentially enriched 1-73(U-(13)C,(15)N)/74-108(U-(15)N) reassembled thioredoxin on multiple time scales using a series of 2D and 3D MAS NMR experiments probing the backbone amide (15)N longitudinal relaxation, (1)H-(15)N dipolar order parameters, (15)N chemical shift anisotropy (CSA), and signal intensities in the temperature-dependent and (1)H T(2)'-filtered NCA experiments. The spin-lattice relaxation rates R(1) (R(1) = 1/T(1)) were observed in the range from 0.012 to 0.64 s(-1), indicating large site-to-site variations in dynamics on pico- to nanosecond time scales. The (1)H-(15)N dipolar order parameters, <S>, and (15)N CSA anisotropies, delta(sigma), reveal the backbone mobilities in reassembled thioredoxin, as reflected in the average <S> = 0.89 +/- 0.06 and delta(sigma) = 92.3 +/- 5.2 ppm, respectively. From the aggregate of experimental data from different dynamics methods, some degree of correlation between the motions on the different time scales has been suggested. Analysis of the dynamics parameters derived from these solid-state NMR experiments indicates higher mobilities for the residues constituting irregular secondary structure elements than for those located in the alpha-helices and beta-sheets, with no apparent systematic differences in dynamics between the alpha-helical and beta-sheet residues. Remarkably, the dipolar order parameters derived from the solid-state NMR measurements and the corresponding solution NMR generalized order parameters display similar qualitative trends as a function of the residue number. The comparison of the solid-state dynamics parameters to the crystallographic B-factors has identified the contribution of static disorder to the B-factors. The combination of longitudinal relaxation, dipolar order parameter, and CSA line shape analyses employed in this study provides snapshots of dynamics and a new insight on the correlation of these motions on multiple time scales.

Dataset Information

Peptide and Protein Dynamics and Low-Temperature/DNP Magic Angle Spinning NMR.

Publications

Peptide and Protein Dynamics and Low-Temperature/DNP Magic Angle Spinning NMR.

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