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Remarkable Rigidity of the Single α-Helical Domain of Myosin-VI As Revealed by NMR Spectroscopy

[Image: see text] Although the α-helix has long been recognized as an all-important element of secondary structure, it generally requires stabilization by tertiary interactions with other parts of a protein’s structure. Highly charged single α-helical (SAH) domains, consisting of a high percentage (...

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Autores principales: Barnes, C. Ashley, Shen, Yang, Ying, Jinfa, Takagi, Yasuharu, Torchia, Dennis A., Sellers, James R., Bax, Ad
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2019
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6556874/
https://www.ncbi.nlm.nih.gov/pubmed/31117653
http://dx.doi.org/10.1021/jacs.9b03116
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author Barnes, C. Ashley
Shen, Yang
Ying, Jinfa
Takagi, Yasuharu
Torchia, Dennis A.
Sellers, James R.
Bax, Ad
author_facet Barnes, C. Ashley
Shen, Yang
Ying, Jinfa
Takagi, Yasuharu
Torchia, Dennis A.
Sellers, James R.
Bax, Ad
author_sort Barnes, C. Ashley
collection PubMed
description [Image: see text] Although the α-helix has long been recognized as an all-important element of secondary structure, it generally requires stabilization by tertiary interactions with other parts of a protein’s structure. Highly charged single α-helical (SAH) domains, consisting of a high percentage (>75%) of Arg, Lys, and Glu residues, are exceptions to this rule but have been difficult to characterize structurally. Our study focuses on the 68-residue medial tail domain of myosin-VI, which is found to contain a highly ordered α-helical structure extending from Glu-6 to Lys-63. High hydrogen exchange protection factors (15–150), small (ca. 4 Hz) (3)J(HNHα) couplings, and a near-perfect fit to an ideal model α-helix for its residual dipolar couplings (RDCs), measured in a filamentous phage medium, support the high regularity of this helix. Remarkably, the hydrogen exchange rates are far more homogeneous than the protection factors derived from them, suggesting that for these transiently broken helices the intrinsic exchange rates derived from the amino acid sequence are not appropriate reference values. (15)N relaxation data indicate a very high degree of rotational diffusion anisotropy (D(∥)/D(⊥) ≈ 7.6), consistent with the hydrodynamic behavior predicted for such a long, nearly straight α-helix. Alignment of the helix by a paramagnetic lanthanide ion attached to its N-terminal region shows a decrease in alignment as the distance from the tagging site increases. This decrease yields a precise measure for the persistence length of 224 ± 10 Å at 20 °C, supporting the idea that the role of the SAH helix is to act as an extension of the myosin-VI lever arm.
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spelling pubmed-65568742019-06-11 Remarkable Rigidity of the Single α-Helical Domain of Myosin-VI As Revealed by NMR Spectroscopy Barnes, C. Ashley Shen, Yang Ying, Jinfa Takagi, Yasuharu Torchia, Dennis A. Sellers, James R. Bax, Ad J Am Chem Soc [Image: see text] Although the α-helix has long been recognized as an all-important element of secondary structure, it generally requires stabilization by tertiary interactions with other parts of a protein’s structure. Highly charged single α-helical (SAH) domains, consisting of a high percentage (>75%) of Arg, Lys, and Glu residues, are exceptions to this rule but have been difficult to characterize structurally. Our study focuses on the 68-residue medial tail domain of myosin-VI, which is found to contain a highly ordered α-helical structure extending from Glu-6 to Lys-63. High hydrogen exchange protection factors (15–150), small (ca. 4 Hz) (3)J(HNHα) couplings, and a near-perfect fit to an ideal model α-helix for its residual dipolar couplings (RDCs), measured in a filamentous phage medium, support the high regularity of this helix. Remarkably, the hydrogen exchange rates are far more homogeneous than the protection factors derived from them, suggesting that for these transiently broken helices the intrinsic exchange rates derived from the amino acid sequence are not appropriate reference values. (15)N relaxation data indicate a very high degree of rotational diffusion anisotropy (D(∥)/D(⊥) ≈ 7.6), consistent with the hydrodynamic behavior predicted for such a long, nearly straight α-helix. Alignment of the helix by a paramagnetic lanthanide ion attached to its N-terminal region shows a decrease in alignment as the distance from the tagging site increases. This decrease yields a precise measure for the persistence length of 224 ± 10 Å at 20 °C, supporting the idea that the role of the SAH helix is to act as an extension of the myosin-VI lever arm. American Chemical Society 2019-05-22 2019-06-05 /pmc/articles/PMC6556874/ /pubmed/31117653 http://dx.doi.org/10.1021/jacs.9b03116 Text en Copyright © 2019 U.S. Government This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
spellingShingle Barnes, C. Ashley
Shen, Yang
Ying, Jinfa
Takagi, Yasuharu
Torchia, Dennis A.
Sellers, James R.
Bax, Ad
Remarkable Rigidity of the Single α-Helical Domain of Myosin-VI As Revealed by NMR Spectroscopy
title Remarkable Rigidity of the Single α-Helical Domain of Myosin-VI As Revealed by NMR Spectroscopy
title_full Remarkable Rigidity of the Single α-Helical Domain of Myosin-VI As Revealed by NMR Spectroscopy
title_fullStr Remarkable Rigidity of the Single α-Helical Domain of Myosin-VI As Revealed by NMR Spectroscopy
title_full_unstemmed Remarkable Rigidity of the Single α-Helical Domain of Myosin-VI As Revealed by NMR Spectroscopy
title_short Remarkable Rigidity of the Single α-Helical Domain of Myosin-VI As Revealed by NMR Spectroscopy
title_sort remarkable rigidity of the single α-helical domain of myosin-vi as revealed by nmr spectroscopy
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6556874/
https://www.ncbi.nlm.nih.gov/pubmed/31117653
http://dx.doi.org/10.1021/jacs.9b03116
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