Biophysical Journal 68: 648-654 (1995)
© 1995 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Salamon, Z Articles by Tollin, G Search for Related Content PubMed PubMed Citation Articles by Salamon, Z Articles by Tollin, G

Photobleaching of the photoactive yellow protein from Ectothiorhodospira halophila promotes binding to lipid bilayers: evidence from surface plasmon resonance spectroscopy.

Department of Biochemistry, University of Arizona, Tucson 85721.

ABSTRACT

The photoactive yellow protein (PYP) from the phototrophic bacterium Ectothiorhodospira halophila is a small, soluble protein that undergoes reversible photobleaching upon blue light irradiation and may function to mediate the negative phototactic response. Based on previous studies of the effects of solvent viscosity and of aliphatic alcohols on PYP photokinetics, we proposed that photobleaching is concomitant with a protein conformational change that exposes a hydrophobic region on the protein surface. In the present investigation, we have used surface plasmon resonance (SPR) spectroscopy to characterize the binding of PYP to lipid bilayers deposited on a thin silver film. SPR spectra demonstrate that the net negatively charged PYP molecule can bind in a saturable manner to electrically neutral, net positively, and net negatively charged bilayers. Illumination with either blue or white light of a PYP solution, which is in contact with the bilayer, at concentrations below saturation results in an increase in the extent of binding, consistent with exposure of a high affinity hydrophobic surface in the photobleached state, a property that may contribute to its biological function. A value for the thickness of the bound PYP layer (23 A), obtained from theoretical fits to the SPR spectra, is consistent with the structure of the protein determined by x-ray crystallography and indicates that the molecule binds with its long axis parallel to the membrane surface.

This article has been cited by other articles:

				J. Vreede, W. Crielaard, K. J. Hellingwerf, and P. G. Bolhuis Predicting the Signaling State of Photoactive Yellow Protein Biophys. J., May 1, 2005; 88(5): 3525 - 3535. [Abstract] [Full Text] [PDF]