Solid-State 13C NMR Detection of a Perturbed 6-s-trans Chromophore in Bacteriorhodopsin†

G. S. Harbison, S. O. Smith, R. A. Mathies, J. A. Pardoen, J. M.L. Courtin, J. Lugtenburg, R. G. Griffin, J. Herzfeld

Research output: Contribution to journalArticle

222 Citations (Scopus)

Abstract

Solid-state 13C magic angle sample spinning NMR spectroscopy has been used to study the ionone ring portion of the chromophore of bacteriorhodopsin. Spectra were obtained from fully hydrated samples regenerated with retinals 13C labeled at positions C-5, C-6, C-7, C-8, and C-18 and from lyophilized samples regenerated with retinals labeled at C-9 and C-13. C-15-labeled samples were studied in both lyophilized and hydrated forms. Three independent NMR parameters (the downfield element of the C-5 chemical shift tensor, the C-8 isotropic chemical shift, and the C-18 longitudinal relaxation time) indicate that the chromophore has a 6-s-trans conformation in the protein, in contrast to the 6-s-cis conformation that is energetically favored for retinoids in solution. We also observe an additional 27 ppm downfield shift in the middle element of the C-5 shift tensor, which provides support for the existence of a negatively charged protein residue near C-5. Evidence for a positive charge near C-7, possibly the counterion for the negative charge, is also discussed. On the basis of these results, we present a new model for the retinal binding site, which has important implications for the mechanism of the "opsin shift" observed in bacteriorhodopsin.

Original languageEnglish (US)
Pages (from-to)6955-6962
Number of pages8
JournalBiochemistry
Volume24
Issue number24
DOIs
StatePublished - Nov 1 1985

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Bacteriorhodopsins
Chemical shift
Chromophores
Tensors
Conformations
Nuclear magnetic resonance
Norisoprenoids
Opsins
Protein Conformation
Retinoids
Relaxation time
Nuclear magnetic resonance spectroscopy
Proteins
Magnetic Resonance Spectroscopy
Binding Sites
Carbon-13 Magnetic Resonance Spectroscopy
C 15

ASJC Scopus subject areas

  • Biochemistry

Cite this

Harbison, G. S., Smith, S. O., Mathies, R. A., Pardoen, J. A., Courtin, J. M. L., Lugtenburg, J., ... Herzfeld, J. (1985). Solid-State 13C NMR Detection of a Perturbed 6-s-trans Chromophore in Bacteriorhodopsin†. Biochemistry, 24(24), 6955-6962. https://doi.org/10.1021/bi00345a031

Solid-State 13C NMR Detection of a Perturbed 6-s-trans Chromophore in Bacteriorhodopsin†. / Harbison, G. S.; Smith, S. O.; Mathies, R. A.; Pardoen, J. A.; Courtin, J. M.L.; Lugtenburg, J.; Griffin, R. G.; Herzfeld, J.

In: Biochemistry, Vol. 24, No. 24, 01.11.1985, p. 6955-6962.

Research output: Contribution to journalArticle

Harbison, GS, Smith, SO, Mathies, RA, Pardoen, JA, Courtin, JML, Lugtenburg, J, Griffin, RG & Herzfeld, J 1985, 'Solid-State 13C NMR Detection of a Perturbed 6-s-trans Chromophore in Bacteriorhodopsin†', Biochemistry, vol. 24, no. 24, pp. 6955-6962. https://doi.org/10.1021/bi00345a031
Harbison GS, Smith SO, Mathies RA, Pardoen JA, Courtin JML, Lugtenburg J et al. Solid-State 13C NMR Detection of a Perturbed 6-s-trans Chromophore in Bacteriorhodopsin†. Biochemistry. 1985 Nov 1;24(24):6955-6962. https://doi.org/10.1021/bi00345a031
Harbison, G. S. ; Smith, S. O. ; Mathies, R. A. ; Pardoen, J. A. ; Courtin, J. M.L. ; Lugtenburg, J. ; Griffin, R. G. ; Herzfeld, J. / Solid-State 13C NMR Detection of a Perturbed 6-s-trans Chromophore in Bacteriorhodopsin†. In: Biochemistry. 1985 ; Vol. 24, No. 24. pp. 6955-6962.
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abstract = "Solid-state 13C magic angle sample spinning NMR spectroscopy has been used to study the ionone ring portion of the chromophore of bacteriorhodopsin. Spectra were obtained from fully hydrated samples regenerated with retinals 13C labeled at positions C-5, C-6, C-7, C-8, and C-18 and from lyophilized samples regenerated with retinals labeled at C-9 and C-13. C-15-labeled samples were studied in both lyophilized and hydrated forms. Three independent NMR parameters (the downfield element of the C-5 chemical shift tensor, the C-8 isotropic chemical shift, and the C-18 longitudinal relaxation time) indicate that the chromophore has a 6-s-trans conformation in the protein, in contrast to the 6-s-cis conformation that is energetically favored for retinoids in solution. We also observe an additional 27 ppm downfield shift in the middle element of the C-5 shift tensor, which provides support for the existence of a negatively charged protein residue near C-5. Evidence for a positive charge near C-7, possibly the counterion for the negative charge, is also discussed. On the basis of these results, we present a new model for the retinal binding site, which has important implications for the mechanism of the {"}opsin shift{"} observed in bacteriorhodopsin.",
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