The role of water in the extracellular half channel of bacteriorhodopsin

Constanta Ganea, Csilla Gergely, Krisztina Ludmann, G. Váró

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The changes in the photocycle of the wild type and several mutant bacteriorhodopsin (D96N, E204Q, and D212N) were studied on dried samples, at relative humidities of 100% and 50%. Samples were prepared from suspensions at pH ~5 and at pH ~9. Intermediate M with unprotonated Schiff base was observed at the lower humidity, even in the case where the photocycle in suspension did not contain this intermediate (mutant D212N, high pH). The photocycle of the dried sample stopped at intermediate M1 in the extracellular conformation; conformation change, switching the accessibility of the Schiff base to the cytoplasmic side, and proton transport did not occur. The photocycle decayed slowly by dissipating the absorbed energy of the photon, and the protein returned to its initial bacteriorhodopsin state, through several M1-like substates. These substates presumably reflect different paths of the proton back to the Schiff base, as a consequence of the bacteriorhodopsin adopting different conformations by stiffening on dehydration. All intermediates requiring conformational change were hindered in the dried form. The concentration of intermediate L, which appears after isomerization of the retinal from all-trans to 13-cis, during local relaxation of the protein, was unusually low in dried samples. The lack of intermediates N and O demonstrated that the M state did not undergo a change from the extracellular to the cytoplasmic conformation (M1 to M2 transition), as already indicated by Fourier transform infrared spectroscopy, quasielastic incoherent neutron scattering, and electric signal measurements described in the literature.

Original languageEnglish
Pages (from-to)2718-2725
Number of pages8
JournalBiophysical Journal
Volume73
Issue number5
Publication statusPublished - 1997

Fingerprint

Bacteriorhodopsins
Schiff Bases
Humidity
Protons
Water
Suspensions
Neutrons
Fourier Transform Infrared Spectroscopy
Photons
Dehydration
Proteins

ASJC Scopus subject areas

  • Biophysics

Cite this

The role of water in the extracellular half channel of bacteriorhodopsin. / Ganea, Constanta; Gergely, Csilla; Ludmann, Krisztina; Váró, G.

In: Biophysical Journal, Vol. 73, No. 5, 1997, p. 2718-2725.

Research output: Contribution to journalArticle

Ganea, C, Gergely, C, Ludmann, K & Váró, G 1997, 'The role of water in the extracellular half channel of bacteriorhodopsin', Biophysical Journal, vol. 73, no. 5, pp. 2718-2725.
Ganea, Constanta ; Gergely, Csilla ; Ludmann, Krisztina ; Váró, G. / The role of water in the extracellular half channel of bacteriorhodopsin. In: Biophysical Journal. 1997 ; Vol. 73, No. 5. pp. 2718-2725.
@article{7cc11cac058c4e68bd7a990cc5dd0f57,
title = "The role of water in the extracellular half channel of bacteriorhodopsin",
abstract = "The changes in the photocycle of the wild type and several mutant bacteriorhodopsin (D96N, E204Q, and D212N) were studied on dried samples, at relative humidities of 100{\%} and 50{\%}. Samples were prepared from suspensions at pH ~5 and at pH ~9. Intermediate M with unprotonated Schiff base was observed at the lower humidity, even in the case where the photocycle in suspension did not contain this intermediate (mutant D212N, high pH). The photocycle of the dried sample stopped at intermediate M1 in the extracellular conformation; conformation change, switching the accessibility of the Schiff base to the cytoplasmic side, and proton transport did not occur. The photocycle decayed slowly by dissipating the absorbed energy of the photon, and the protein returned to its initial bacteriorhodopsin state, through several M1-like substates. These substates presumably reflect different paths of the proton back to the Schiff base, as a consequence of the bacteriorhodopsin adopting different conformations by stiffening on dehydration. All intermediates requiring conformational change were hindered in the dried form. The concentration of intermediate L, which appears after isomerization of the retinal from all-trans to 13-cis, during local relaxation of the protein, was unusually low in dried samples. The lack of intermediates N and O demonstrated that the M state did not undergo a change from the extracellular to the cytoplasmic conformation (M1 to M2 transition), as already indicated by Fourier transform infrared spectroscopy, quasielastic incoherent neutron scattering, and electric signal measurements described in the literature.",
author = "Constanta Ganea and Csilla Gergely and Krisztina Ludmann and G. V{\'a}r{\'o}",
year = "1997",
language = "English",
volume = "73",
pages = "2718--2725",
journal = "Biophysical Journal",
issn = "0006-3495",
publisher = "Biophysical Society",
number = "5",

}

TY - JOUR

T1 - The role of water in the extracellular half channel of bacteriorhodopsin

AU - Ganea, Constanta

AU - Gergely, Csilla

AU - Ludmann, Krisztina

AU - Váró, G.

PY - 1997

Y1 - 1997

N2 - The changes in the photocycle of the wild type and several mutant bacteriorhodopsin (D96N, E204Q, and D212N) were studied on dried samples, at relative humidities of 100% and 50%. Samples were prepared from suspensions at pH ~5 and at pH ~9. Intermediate M with unprotonated Schiff base was observed at the lower humidity, even in the case where the photocycle in suspension did not contain this intermediate (mutant D212N, high pH). The photocycle of the dried sample stopped at intermediate M1 in the extracellular conformation; conformation change, switching the accessibility of the Schiff base to the cytoplasmic side, and proton transport did not occur. The photocycle decayed slowly by dissipating the absorbed energy of the photon, and the protein returned to its initial bacteriorhodopsin state, through several M1-like substates. These substates presumably reflect different paths of the proton back to the Schiff base, as a consequence of the bacteriorhodopsin adopting different conformations by stiffening on dehydration. All intermediates requiring conformational change were hindered in the dried form. The concentration of intermediate L, which appears after isomerization of the retinal from all-trans to 13-cis, during local relaxation of the protein, was unusually low in dried samples. The lack of intermediates N and O demonstrated that the M state did not undergo a change from the extracellular to the cytoplasmic conformation (M1 to M2 transition), as already indicated by Fourier transform infrared spectroscopy, quasielastic incoherent neutron scattering, and electric signal measurements described in the literature.

AB - The changes in the photocycle of the wild type and several mutant bacteriorhodopsin (D96N, E204Q, and D212N) were studied on dried samples, at relative humidities of 100% and 50%. Samples were prepared from suspensions at pH ~5 and at pH ~9. Intermediate M with unprotonated Schiff base was observed at the lower humidity, even in the case where the photocycle in suspension did not contain this intermediate (mutant D212N, high pH). The photocycle of the dried sample stopped at intermediate M1 in the extracellular conformation; conformation change, switching the accessibility of the Schiff base to the cytoplasmic side, and proton transport did not occur. The photocycle decayed slowly by dissipating the absorbed energy of the photon, and the protein returned to its initial bacteriorhodopsin state, through several M1-like substates. These substates presumably reflect different paths of the proton back to the Schiff base, as a consequence of the bacteriorhodopsin adopting different conformations by stiffening on dehydration. All intermediates requiring conformational change were hindered in the dried form. The concentration of intermediate L, which appears after isomerization of the retinal from all-trans to 13-cis, during local relaxation of the protein, was unusually low in dried samples. The lack of intermediates N and O demonstrated that the M state did not undergo a change from the extracellular to the cytoplasmic conformation (M1 to M2 transition), as already indicated by Fourier transform infrared spectroscopy, quasielastic incoherent neutron scattering, and electric signal measurements described in the literature.

UR - http://www.scopus.com/inward/record.url?scp=0030780883&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030780883&partnerID=8YFLogxK

M3 - Article

C2 - 9370465

AN - SCOPUS:0030780883

VL - 73

SP - 2718

EP - 2725

JO - Biophysical Journal

JF - Biophysical Journal

SN - 0006-3495

IS - 5

ER -