The tertiary structural changes in bacteriorhodopsin occur between M states: X-ray diffraction and Fourier transform infrared spectroscopy
The tertiary structural changes occurring during the photocycle of bacteriorhodopsin (BR) are assigned by X‐ray diffraction to distinct M states, M1 and M2. Purple membranes (PM) of the mutant Asp96Asn at 15, 57, 75 and 100% relative humidity (r.h.) were studied in a parallel X‐ray diffraction and F...
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Published in | The EMBO journal Vol. 16; no. 7; pp. 1484 - 1491 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Chichester, UK
John Wiley & Sons, Ltd
01.04.1997
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Subjects | |
Online Access | Get full text |
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Summary: | The tertiary structural changes occurring during the photocycle of bacteriorhodopsin (BR) are assigned by X‐ray diffraction to distinct M states, M1 and M2. Purple membranes (PM) of the mutant Asp96Asn at 15, 57, 75 and 100% relative humidity (r.h.) were studied in a parallel X‐ray diffraction and Fourier transform infrared (FTIR) spectroscopic investigation. Light‐dependent conformational changes of BR‐Asp96Asn are observed at high hydration levels (100 and 75% r.h.) but not in partially dehydrated samples (57 and 15% r.h.). The FTIR spectra of continuously illuminated samples at low and high hydration, despite some differences, are characteristic of the M intermediate. The changes in diffraction patterns of samples in the M2 state are of the same magnitude as those of wild‐type samples trapped with GuaHCl in the MG state. Additional large changes in the amide bands of the FTIR spectra occur between M2 and MG. This suggests, that the tertiary structural changes between M1 and M2 are responsible for the switch opening the cytoplasmic half‐channel of BR for reprotonation to complete the catalytic cycle. These tertiary structural changes seem to be triggered by a charge redistribution which might be a common feature of retinal proteins also in signal transduction. |
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Bibliography: | ark:/67375/WNG-LHCX2L43-1 istex:00AB9FADA59E24ED69A52390FE34430D30A36931 ArticleID:EMBJ7590138 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 0261-4189 1460-2075 1460-2075 |
DOI: | 10.1093/emboj/16.7.1484 |