Secondary structure analysis of purified functional CHIP28 water channels by CD and FTIR spectroscopy

Hoek, Alfred N. Van; Wiener, Michael C.; Bicknese, S.; Miercke, Larry J. W.; Biwersi, Joachim; Verkman, A. S.

doi:10.1021/bi00095a013

Cited by 72 publications

(54 citation statements)

References 40 publications

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“…This could be related to the fact that the main function of the CHIP28 protein is to act as a water channel. The main function of the [20], using CHIP28 in a partially dehydrated state; the CD analysis is from of van Hoek et al [20], with CHIP28 in an aqueous medium. The error margins for FTIR analyses I and I1 are related to the factor analysis method used [27].…”

Section: Resultsmentioning

confidence: 99%

“…The error margins for FTIR analyses I and I1 are related to the factor analysis method used [27]. For FTIR analysis I11 and the CD analysis, the mean error margin for 3-5 separate spectral determinations [20] is presented. glucose transporter is in transporting sugars.…”

Section: Resultsmentioning

confidence: 99%

“…The CHIP28 protein in N-lauroylsarcosine-stripped ghost membranes used in our studies is similar to the preparation used by van Hoek et al [20]. Approximately 5O-pl aliquots of the membrane protein, suspended in aqueous buffer, were placed between two CaF, windows separated by either a 6 pm tin (for H,O samples) or 50 pm Teflon (for 'H,O) spacer.…”

Section: Methodsmentioning

confidence: 99%

“…FTIR spectra of the lyophilised samples were similar to those of non-lyophilised samples. Van Hoek et al [20] in their FTIR study obtained dehydrated films of the CHIP28 protein. For comparison, we have also obtained such films for our studies.…”

Section: Methodsmentioning

confidence: 99%

“…Infrared spectra of membrane protein contain bands from the different functional groups present and it is possible to obtain information on protein secondary structure, amino acid side chains, hydrogen-deuterium exchange, thermal denaturation characteristics and other properties [is, 191. A previous FTIR study on CHIP28 has been reported [20]. However, the measurements were limited to dry samples and detailed analysis using derivative and deconvolution procedures were not carried out, presumably due to the poor signal-to-noise ratio of the spectra.…”

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confidence: 99%

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A Fourier‐Transform Infrared Spectroscopic Investigation of the Hydrogen‐Deuterium Exchange and Secondary Structure of the 28‐kDa Channel‐Forming Integral Membrane Protein (CHIP28)

Haris

Chapman

Benga

1995

European Journal of Biochemistry

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Fourier-transform infrared spectroscopy (FTIR) has been employed to investigate the structural properties of the 28-kDa channel-forming integral membrane protein (CHIP28) present in phospholipid vesicles suspended in aqueous media. This study reports the FTIR spectra of this membrane protein present in H,O and *H,O. The secondary structure of the protein was determined and found to consist of 36% ahelical and 42% P-sheet structures. These results are in close agreement with the results of a previous CD study [Van Hoek, A. N., Wiener, M., Bicknese, S., Miercke, L., Biwersi, J. & Verkman, A. S. (1993) Biochemistry 32, 11 847-11 8561. However, the results differ from those given in an FTIR analysis by the same workers who recorded FTIR spectra of the CHIP28 protein in a dehydrated state. An unusually high extent of hydrogen-deuterium exchange of the peptide groups of this protein occurs. The magnitude of the spectral changes observed upon exposure of the protein to 'H,O is greater than has been observed with any other membrane protein previously studied. Thus, over 80% of the peptide groups exchange within 5 min and the amide I band maximum shifts to low frequency by approximately 20 cm-'. This high hydrogen-deuterium exchange observed with the CHIP28 protein is consistent with the presence of an aqueous pore within the protein structure.Keyvvords: membrane protein conformation ; 28-kDa channel-forming integral membrane protein (CHIP28) ; water channel : Fourier-transform infrared spectroscopy ; hydrogen-deuterium exchange.One of the main functions of the plasma membrane of living cells is the control of movement of water and solutes into and out of the cell. The availability, its simple structure (i.e. the lack of intracellular membranes), and the rather detailed knowledge of its biomembrane structure makes the red blood cell (RBC) ideally suited for studying plasma membrane permeability. A prominent feature of the RBC membrane is its high permeability to water [I]. Recognition of very high water transport across RBC plasma membranes, the low activation energy of this process [2, 31, and the inhibitory effects of mercurial SH blocking reagents [4-61 has led to the suggestion that water channels must be present within some of these membrane proteins 17-101.Consistent with this hypothesis, the first channel-forming integral membrane protein of molecular mass 28 kDa (called CHIP28 or aquaporin) from RBC was identified by Agre and coworkers [I 21. The CHIP-mediated water channel activity was demonstrated both with a Xenopus laevis oocyte expression system and also with CHIP28 reconstituted into liposomes 112-141. In both systems, CHIP28 markedly increases the water per- Abhreviutions. CHIP28, 28-kDa channel-forming integral membrane protein; FTIR, Fourier-transform infrared spectroscopy; RBC, red blood cell(s).Note. The permanent address of' G. Benga is: Department of Cell and Molecular Biology, 'Iulin Hatiagano' University of Medicine and Pharmacy, Cluj-Napoca, 6 Pasteur St., RO-3400 Cluj-Napoca, Romania. meabilit...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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A Fourier‐Transform Infrared Spectroscopic Investigation of the Hydrogen‐Deuterium Exchange and Secondary Structure of the 28‐kDa Channel‐Forming Integral Membrane Protein (CHIP28)

Haris

Chapman

Benga

1995

European Journal of Biochemistry

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Quantitation of the water channel protein aquaporin (CHIP28) from red blood cell membranes by densitometry of silver stained polyacrylamide gels

1996

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A protein determination procedure which involves the densitometry of silver stained polyacrylamide gels is described. It involves calibration with bovine serum albumin and molecular weight markers on the same gel with the protein to be quantitated. The procedure is simple, rapid, reproducible and accurate and is more sensitive than other procedures for protein determination. The procedure is particularly useful in quantitating proteins purified in small amounts since the determination can be performed on the same gel used to check the purification. It avoids interference by detergents and other substances usually present in solutions of purified proteins. The procedure has been applied to the quantitation of a recently identified protein, aquaporin (CHIP28), assumed to be a major water channel in the red blood cell membrane. A quantitative analysis of a purified fraction of this protein shows that the 28 kDa component represents approximately two thirds of the protein content of the sample, with the remainder comprising a glycosylated, high molecular mass component. The procedure may be useful for quantitating proteins revealed on silver stained gels and could be included as a standard part of any protocol for protein purification.

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The three-dimensional structure of human erythrocyte aquaporin CHIP.

et al. 1994

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Water‐permeable membranes of several plant and mammalian tissues contain specific water channel proteins, the ‘aquaporins’. The best characterized aquaporin is CHIP, a 28 kDa red blood cell channel‐forming integral protein. Isolated CHIP and Escherichia coli lipids may be assembled into 2‐D crystals for structural analyses. Here we present (i) a structural characterization of the solubilized CHIP oligomers, (ii) projections of CHIP arrays after negative staining or metal‐shadowing, and (iii) the 3‐D structure at 1.6 nm resolution. Negatively stained CHIP oligomers exhibited a side length of 6.9 nm with four‐fold symmetry, and a mass of 202 +/‐ 3 kDa determined by scanning transmission electron microscopy. Reconstituted into lipid bilayers, CHIP formed 2‐D square lattices with unit cell dimensions a = b = 9.6 nm and a p422(1) symmetry. The 3‐D map revealed that CHIP tetramers contain central stain‐filled depressions about the fourfold axis. These cavities extend from both sides into the transbilayer domain of the molecule leaving only a thin barrier to be penetrated by the water pores. Although CHIP monomers behave as independent pores, we propose that their particular structure requires tetramerization for stable integration into the bilayer.

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Secondary structure analysis of purified functional CHIP28 water channels by CD and FTIR spectroscopy

Cited by 72 publications

References 40 publications

A Fourier‐Transform Infrared Spectroscopic Investigation of the Hydrogen‐Deuterium Exchange and Secondary Structure of the 28‐kDa Channel‐Forming Integral Membrane Protein (CHIP28)

A Fourier‐Transform Infrared Spectroscopic Investigation of the Hydrogen‐Deuterium Exchange and Secondary Structure of the 28‐kDa Channel‐Forming Integral Membrane Protein (CHIP28)

Quantitation of the water channel protein aquaporin (CHIP28) from red blood cell membranes by densitometry of silver stained polyacrylamide gels

The three-dimensional structure of human erythrocyte aquaporin CHIP.

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