Structural characterization of the L-to-M transition of the bacteriorhodopsin photocycle.

Structural intermediates occurring in the photocycle of wild-type bacteriorhodopsin are trapped by illuminating hydrated, glucose-embedded purple membrane at 170 K, 220 K, 230 K, and 240 K. We characterize light-induced changes in protein conformation by electron diffraction difference Fourier maps,...

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Main Authors: Hendrickson, F M, Burkard, F, Glaeser, R M
Formato: Artigo
Idioma:English
Publicado em: 1998
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Research Article
Acesso em linha:https://ncbi.nlm.nih.gov/pmc/articles/PMC1299819/
https://ncbi.nlm.nih.gov/pubmed/9726946
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spelling pubmed-12998192006-01-17 Structural characterization of the L-to-M transition of the bacteriorhodopsin photocycle. Hendrickson, F M Burkard, F Glaeser, R M Biophys J Research Article Structural intermediates occurring in the photocycle of wild-type bacteriorhodopsin are trapped by illuminating hydrated, glucose-embedded purple membrane at 170 K, 220 K, 230 K, and 240 K. We characterize light-induced changes in protein conformation by electron diffraction difference Fourier maps, and relate these to previous work on photocycle intermediates by infrared (FTIR) spectroscopy. Samples illuminated at 170 K are confirmed by FTIR spectroscopy to be in the L state; a difference Fourier projection map shows no structural change within the 0.35-nm resolution limit of our data. Difference maps obtained with samples illuminated at 220 K, 230 K, and 240 K, respectively, reveal a progressively larger structural response in helix F when the protein is still in the M state, as judged by the FTIR spectra. Consistent with previous structural studies, an adjustment in the position or in the degree of ordering of helix G accompanies this motion. The model of the photocycle emerging from this and previous studies is that bacteriorhodopsin experiences minimal change in protein structure until a proton is transferred from the Schiff base to Asp85. The M intermediate then undergoes a conformational evolution that opens a hydrated "half-channel," allowing the subsequent reprotonation of the Schiff base by Asp96. 1998-09 /pmc/articles/PMC1299819/ /pubmed/9726946 Text en
institution US National Library of Medicine
collection PubMed Central
language English
format Article
topic Research Article
spellingShingle Research Article
Hendrickson, F M
Burkard, F
Glaeser, R M
Structural characterization of the L-to-M transition of the bacteriorhodopsin photocycle.
description Structural intermediates occurring in the photocycle of wild-type bacteriorhodopsin are trapped by illuminating hydrated, glucose-embedded purple membrane at 170 K, 220 K, 230 K, and 240 K. We characterize light-induced changes in protein conformation by electron diffraction difference Fourier maps, and relate these to previous work on photocycle intermediates by infrared (FTIR) spectroscopy. Samples illuminated at 170 K are confirmed by FTIR spectroscopy to be in the L state; a difference Fourier projection map shows no structural change within the 0.35-nm resolution limit of our data. Difference maps obtained with samples illuminated at 220 K, 230 K, and 240 K, respectively, reveal a progressively larger structural response in helix F when the protein is still in the M state, as judged by the FTIR spectra. Consistent with previous structural studies, an adjustment in the position or in the degree of ordering of helix G accompanies this motion. The model of the photocycle emerging from this and previous studies is that bacteriorhodopsin experiences minimal change in protein structure until a proton is transferred from the Schiff base to Asp85. The M intermediate then undergoes a conformational evolution that opens a hydrated "half-channel," allowing the subsequent reprotonation of the Schiff base by Asp96.
author Hendrickson, F M
Burkard, F
Glaeser, R M
author_facet Hendrickson, F M
Burkard, F
Glaeser, R M
author_sort Hendrickson, F M
title Structural characterization of the L-to-M transition of the bacteriorhodopsin photocycle.
title_short Structural characterization of the L-to-M transition of the bacteriorhodopsin photocycle.
title_full Structural characterization of the L-to-M transition of the bacteriorhodopsin photocycle.
title_fullStr Structural characterization of the L-to-M transition of the bacteriorhodopsin photocycle.
title_full_unstemmed Structural characterization of the L-to-M transition of the bacteriorhodopsin photocycle.
title_sort structural characterization of the l-to-m transition of the bacteriorhodopsin photocycle.
publishDate 1998
url https://ncbi.nlm.nih.gov/pmc/articles/PMC1299819/
https://ncbi.nlm.nih.gov/pubmed/9726946
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