Abstract
Electric field induced conformational changes of bacteriorhodopsin were studied in six types of dried film (randomly and electrically oriented membranes of purple as well as cation-depleted blue bacteriorhodopsin) by measuring the frequency dependence of the optical absorbance change and the dielectric dispersion and absorption. For the purple bacteriorhodopsin the optical absorbance change induced by alternating rectangular electric fields of ±300 kV/cm altered the sign twice in the frequency range from 0.001 Hz to 100 kHz (around 0.03 Hz and 100 kHz), indicating that the electric field induced conformational change in these samples consists of, at least, three steps. Similarly, it was found for the blue bacteriorhodopsin that at least two steps are involved. In accord with optical measurements, the dielectric behaviour due to alternating sinusoidal electric fields of±6kV/cm in the frequency range from 10 Hz to 10 MHz showed two broad dispersion/absorption regions, one below 1 kHz and the other around 10–100 kHz. This suggests that the conformational change of bacteriorhodopsin is also reflected by its dielectrical properties and that it is partially induced at 6 kV/cm. Including previous results obtained by analysis of the action of DC fields on purple membrane films, a model for a field-induced cyclic reaction for purple as well as blue bacteriorhodopsin is proposed. In addition it was found that there are electrical interactions among purple membrane fragments in dried films.
Similar content being viewed by others
References
Böttcher CJF, Bordewijk P (1978) Theory of electric polarization, Vol II. Elsevier, Amsterdam
Borisevitch GP, Lukashev EP, Kononenko AA, Rubin AB (1979) Bacteriorhodopsin (BR570) bathochromic band shift in an external electric field. Biochim Biophys Acta 546:171–174
Chamorovsky SK, Lukashev EP, Kononenko AA, Rubin AB (1983) Effects of electric field on the photocycle of bacteriorhodopsin. Biochim Biophys Acta 725:403–406
Fisher K, Yanagimoto K, Stoeckenius W (1978) Oriented absorption of purple membrane to cation surfaces. J Cell Biol 77:611–620
Fredericq E, Houssier C (1973) Electric dichroism and electric birefringence. Clarendon Press, Oxford
Govindjee R, Ebrey TG, Crofts AR (1980) The quantum efficiency of proton pumping by the purple membrane of Halobacterium halobium. Biophys J 30:231–242
Hess B (1978) Intervention. In: Lefever R (ed) Molecular movements and chemical reactivity. John Wiley and Sons, New York, pp 226–227
Kimura Y, Ikegami A, Stoeckenius W (1984) Salt and pH-dependent changes of the purple membrane absorption spectrum. Photochem Photobiol 40:641–646
Kohl K-D, Engelhard M, Hess B (1984) Specific requirement of cations for the photocycle of bacteriorhodopsin (bR). EBEC Rep 3 B:647
Korenstein R, Hess B (1977a) Hydration effects on cis-trans isomerization of bacteriorhodopsin. FEBS Lett 82:7–11
Korenstein R, Hess B (1977b) Hydration effects on the photocycle of bacteriorhodopsin in thin layers of purple membrane. Nature 270:184–186
Korenstein R, Hess B (1982) Analysis of photocycle and orientation in thin layers. Methods Enzymol 88:180–193
Lozier RH, Bogomolni RA, Stoeckenius W (1975) Bacteriorhodopsin: a light-driven proton pump in Halobacterium halobium. Biophys J 15:955–962
Lukashev EP, Vozary E, Kononenko AA, Rubin AB (1980) Electric field promotion of the bacteriorhodopsin BR570 to BR412 photo-conversion in films of Halobacterium halobium purple membranes. Biochim Biophys Acta 592:258–266
Maximychev AB, Lukashev EP, Kononenko AA, Chekulaeva LN, Timashev SF (1984) Photopotential and electric field regeneration of bacteriorhodopsin photocycles in highly oriented purple membrane films. Biol Membr 1:294–304
Michel H, Oesterhelt D (1976) Light-induced changes of the pH gradient and the membrane potential in H. halobium. FEBS Lett 65:175–178
Oesterhelt D, Stoeckenius W (1974) Isolation of the cell membrane of Halobacterium halobium and its fractionation into red and purple membrane. Methods Enzymol 31 A: 667–678
Oesterhelt D, Meentzen M, Schuhmann L (1973) Reversible dissociation of the purple complex in bacteriorhodopsin and identification of 13-cis and all-trans-retinal as its chromophores. Eur J Biochem 40:453–463
Shinar R, Druckmann S, Ottolenghi M, Korenstein R (1977) Electric field effects in bacteriorhodopsin. Biophys J 19:1–5
Tsuji K, Hess B (1986) Electric field induced conformational changes of bacteriorhodopsin in purple membrane dried films. I. DC field effects. Eur Biophys J 13:273–280
Tsuji K, Neumann E (1981a) Structural changes in bacteriorhodopsin induced by electric impulses. Int. J Biol Macromol 3:231–242
Tsuji K, Neumann E (1981b) Electric field induced pK changes in bacteriorhodopsin. FEBS Lett 128:265–268
Tsuji K, Neumann E (1983) Conformational flexibility of membrane proteins in electric fields. I. Ultraviolet absorbance and light scattering of bacteriorhodopsin in purple membranes. Biophys Chem 17:153–163
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Tsuji, K., Müller, S.C. & Hess, B. Electric field induced conformational changes of bacteriorhodopsin in purple membrane films. Eur Biophys J 15, 329–337 (1988). https://doi.org/10.1007/BF00254720
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00254720