Fourier Transform Infrared Study of the Halorhodopsin Chloride Pump

Kenneth J. Rothschild, Olaf Bousché, Mark S. Braiman, C. A. Hasselbacher, John L. Spudich

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45 Scopus citations

Abstract

halorhodopsin(hR) is a light-driven chloride pump located in the cell membrane of Halo-bacterium halobium. Fourier transform infrared difference spectroscopy has been used to study structural alterations occurring during the hR photocycle. The frequencies of peaks attributed to the retinylidene chromophore are similar to those observed in the spectra of the related protein bacteriorhodopsin (bR), indicating that in hR as in bR an all-trans → 13-cis isomerization occurs during formation of the early bathoproduct. Spectral features due to protein structural alterations are also similar for the bR and hR photocycles. For example, formation of the red-shifted primary photoproducts of both hR and bR results in similar carboxyl peaks in the 1730-1745-cm-1region. However, in contrast to bR, no further changes are observed in the carboxyl region during subsequent steps in the hR photocycle, indicating that additional carboxyl groups are not directly involved in chloride translocation. Overall, the close similarity of vibrations in hR and bR photoproduct difference spectra supports the existence of some common elements in the molecular mechanisms of energy transduction and active transport by these two proteins.

Original languageEnglish (US)
Pages (from-to)2420-2424
Number of pages5
JournalBiochemistry
Volume27
Issue number7
DOIs
StatePublished - Apr 1 1988

ASJC Scopus subject areas

  • Biochemistry

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    Rothschild, K. J., Bousché, O., Braiman, M. S., Hasselbacher, C. A., & Spudich, J. L. (1988). Fourier Transform Infrared Study of the Halorhodopsin Chloride Pump. Biochemistry, 27(7), 2420-2424. https://doi.org/10.1021/bi00407a026