Secondary structures comparison of aquaporin-1 and bacteriorhodopsin: A Fourier transform infrared spectroscopy study of two-dimensional membrane crystals

Véronique Cabiaux, Keith A. Oberg, Petr Pancoska, Thomas Walz, Peter C Agre, Andreas Engel

Research output: Contribution to journalArticle

Abstract

Aquaporins are integral membrane proteins found in diverse animal and plant tissues that mediate the permeability of plasma membranes to water molecules. Projection maps of two-dimensional crystals of aquaporin-1 (AQP1) reconstituted in lipid membranes suggested the presence of six to eight transmembrane helices in the protein. However, data from other sequence and spectroscopic analyses indicate that this protein may adopt a porin-like β- barrel fold. In this paper, we use Fourier transform infrared spectroscopy to characterize the secondary structure of highly purified native and proteolyzed AQP1 reconstituted in membrane crystalline arrays and compare it to bacteriorhodopsin. For this analysis the fractional secondary structure contents have been determined by using several different algorithms. In addition, a neural network-based evaluation of the Fourier transform infrared spectra in terms of numbers of secondary structure segments and their interconnections [s(ij)] has been performed. The following conclusions were reached: 1) AQP1 is a highly helical protein (42-48% α-helix) with little or no β-sheet content. 2) The α-helices have a transmembrane orientation, but are more tilted (21°or 27°, depending on the considered refractive index) than the bacteriorhodopsin helices. 3) The helices in AQP1 undergo limited hydrogen/deuterium exchange and thus are not readily accessible to solvent. Our data support the AQP1 structural model derived from sequence prediction and epitope insertion experiments: AQP1 is a protein with at least six closely associated α-helices that span the lipid membrane.

Original languageEnglish (US)
Pages (from-to)406-417
Number of pages12
JournalBiophysical Journal
Volume73
Issue number1
StatePublished - Jul 1997

Fingerprint

Aquaporin 1
Bacteriorhodopsins
Fourier Transform Infrared Spectroscopy
Membranes
Membrane Lipids
Proteins
Porins
Refractometry
Aquaporins
Deuterium
Structural Models
Fourier Analysis
Sequence Analysis
Epitopes
Hydrogen
Permeability
Membrane Proteins
Cell Membrane
Water

ASJC Scopus subject areas

  • Biophysics

Cite this

Secondary structures comparison of aquaporin-1 and bacteriorhodopsin : A Fourier transform infrared spectroscopy study of two-dimensional membrane crystals. / Cabiaux, Véronique; Oberg, Keith A.; Pancoska, Petr; Walz, Thomas; Agre, Peter C; Engel, Andreas.

In: Biophysical Journal, Vol. 73, No. 1, 07.1997, p. 406-417.

Research output: Contribution to journalArticle

Cabiaux, Véronique ; Oberg, Keith A. ; Pancoska, Petr ; Walz, Thomas ; Agre, Peter C ; Engel, Andreas. / Secondary structures comparison of aquaporin-1 and bacteriorhodopsin : A Fourier transform infrared spectroscopy study of two-dimensional membrane crystals. In: Biophysical Journal. 1997 ; Vol. 73, No. 1. pp. 406-417.
@article{e7b5dfad339248638eb247ec2c8cb935,
title = "Secondary structures comparison of aquaporin-1 and bacteriorhodopsin: A Fourier transform infrared spectroscopy study of two-dimensional membrane crystals",
abstract = "Aquaporins are integral membrane proteins found in diverse animal and plant tissues that mediate the permeability of plasma membranes to water molecules. Projection maps of two-dimensional crystals of aquaporin-1 (AQP1) reconstituted in lipid membranes suggested the presence of six to eight transmembrane helices in the protein. However, data from other sequence and spectroscopic analyses indicate that this protein may adopt a porin-like β- barrel fold. In this paper, we use Fourier transform infrared spectroscopy to characterize the secondary structure of highly purified native and proteolyzed AQP1 reconstituted in membrane crystalline arrays and compare it to bacteriorhodopsin. For this analysis the fractional secondary structure contents have been determined by using several different algorithms. In addition, a neural network-based evaluation of the Fourier transform infrared spectra in terms of numbers of secondary structure segments and their interconnections [s(ij)] has been performed. The following conclusions were reached: 1) AQP1 is a highly helical protein (42-48{\%} α-helix) with little or no β-sheet content. 2) The α-helices have a transmembrane orientation, but are more tilted (21°or 27°, depending on the considered refractive index) than the bacteriorhodopsin helices. 3) The helices in AQP1 undergo limited hydrogen/deuterium exchange and thus are not readily accessible to solvent. Our data support the AQP1 structural model derived from sequence prediction and epitope insertion experiments: AQP1 is a protein with at least six closely associated α-helices that span the lipid membrane.",
author = "V{\'e}ronique Cabiaux and Oberg, {Keith A.} and Petr Pancoska and Thomas Walz and Agre, {Peter C} and Andreas Engel",
year = "1997",
month = "7",
language = "English (US)",
volume = "73",
pages = "406--417",
journal = "Biophysical Journal",
issn = "0006-3495",
publisher = "Biophysical Society",
number = "1",

}

TY - JOUR

T1 - Secondary structures comparison of aquaporin-1 and bacteriorhodopsin

T2 - A Fourier transform infrared spectroscopy study of two-dimensional membrane crystals

AU - Cabiaux, Véronique

AU - Oberg, Keith A.

AU - Pancoska, Petr

AU - Walz, Thomas

AU - Agre, Peter C

AU - Engel, Andreas

PY - 1997/7

Y1 - 1997/7

N2 - Aquaporins are integral membrane proteins found in diverse animal and plant tissues that mediate the permeability of plasma membranes to water molecules. Projection maps of two-dimensional crystals of aquaporin-1 (AQP1) reconstituted in lipid membranes suggested the presence of six to eight transmembrane helices in the protein. However, data from other sequence and spectroscopic analyses indicate that this protein may adopt a porin-like β- barrel fold. In this paper, we use Fourier transform infrared spectroscopy to characterize the secondary structure of highly purified native and proteolyzed AQP1 reconstituted in membrane crystalline arrays and compare it to bacteriorhodopsin. For this analysis the fractional secondary structure contents have been determined by using several different algorithms. In addition, a neural network-based evaluation of the Fourier transform infrared spectra in terms of numbers of secondary structure segments and their interconnections [s(ij)] has been performed. The following conclusions were reached: 1) AQP1 is a highly helical protein (42-48% α-helix) with little or no β-sheet content. 2) The α-helices have a transmembrane orientation, but are more tilted (21°or 27°, depending on the considered refractive index) than the bacteriorhodopsin helices. 3) The helices in AQP1 undergo limited hydrogen/deuterium exchange and thus are not readily accessible to solvent. Our data support the AQP1 structural model derived from sequence prediction and epitope insertion experiments: AQP1 is a protein with at least six closely associated α-helices that span the lipid membrane.

AB - Aquaporins are integral membrane proteins found in diverse animal and plant tissues that mediate the permeability of plasma membranes to water molecules. Projection maps of two-dimensional crystals of aquaporin-1 (AQP1) reconstituted in lipid membranes suggested the presence of six to eight transmembrane helices in the protein. However, data from other sequence and spectroscopic analyses indicate that this protein may adopt a porin-like β- barrel fold. In this paper, we use Fourier transform infrared spectroscopy to characterize the secondary structure of highly purified native and proteolyzed AQP1 reconstituted in membrane crystalline arrays and compare it to bacteriorhodopsin. For this analysis the fractional secondary structure contents have been determined by using several different algorithms. In addition, a neural network-based evaluation of the Fourier transform infrared spectra in terms of numbers of secondary structure segments and their interconnections [s(ij)] has been performed. The following conclusions were reached: 1) AQP1 is a highly helical protein (42-48% α-helix) with little or no β-sheet content. 2) The α-helices have a transmembrane orientation, but are more tilted (21°or 27°, depending on the considered refractive index) than the bacteriorhodopsin helices. 3) The helices in AQP1 undergo limited hydrogen/deuterium exchange and thus are not readily accessible to solvent. Our data support the AQP1 structural model derived from sequence prediction and epitope insertion experiments: AQP1 is a protein with at least six closely associated α-helices that span the lipid membrane.

UR - http://www.scopus.com/inward/record.url?scp=0030997806&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030997806&partnerID=8YFLogxK

M3 - Article

C2 - 9199804

AN - SCOPUS:0030997806

VL - 73

SP - 406

EP - 417

JO - Biophysical Journal

JF - Biophysical Journal

SN - 0006-3495

IS - 1

ER -