Ultrasensitive Measurements of Microbial Rhodopsin Photocycles Using Photochromic FRET

  1. Halil Bayraktar1,
  2. Alexander P. Fields2,
  3. Joel M. Kralj1,
  4. John L. Spudich3,
  5. Kenneth J. Rothschild4,
  6. Adam E. Cohen1,5,*

Article first published online: 17 NOV 2011

DOI: 10.1111/j.1751-1097.2011.01011.x

Issue

Photochemistry and Photobiology

Photochemistry and Photobiology

Volume 88, Issue 1, pages 90–97, January/February 2012

Additional Information

How to Cite

Bayraktar, H., Fields, A. P., Kralj, J. M., Spudich, J. L., Rothschild, K. J. and Cohen, A. E. (2012), Ultrasensitive Measurements of Microbial Rhodopsin Photocycles Using Photochromic FRET. Photochemistry and Photobiology, 88: 90–97. doi: 10.1111/j.1751-1097.2011.01011.x

Author Information

  1. 1

    Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA

  2. 2

    Graduate Program in Biophysics, Harvard University, Cambridge, MA

  3. 3

    Department of Biochemistry and Molecular Biology, Center for Membrane Biology, The University of Texas Health Science Center, Houston, TX

  4. 4

    Department of Physics and Photonics Center, Boston University, Boston, MA

  5. 5

    Department of Physics, Harvard University, Cambridge, MA

* Corresponding author email: cohen@chemistry.harvard.edu (Adam Cohen)

Publication History

  1. Issue published online: 3 JAN 2012
  2. Article first published online: 17 NOV 2011
  3. Accepted manuscript online: 19 OCT 2011 11:20AM EST
  4. Received 12 July 2011, accepted 27 September 2011

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Abstract

Microbial rhodopsins are an important class of light-activated transmembrane proteins whose function is typically studied on bulk samples. Herein, we apply photochromic fluorescence resonance energy transfer to investigate the dynamics of these proteins with sensitivity approaching the single-molecule limit. The brightness of a covalently linked organic fluorophore is modulated by changes in the absorption spectrum of the endogenous retinal chromophore that occur as the molecule undergoes a light-activated photocycle. We studied the photocycles of blue-absorbing proteorhodopsin and sensory rhodopsin II (SRII). Clusters of 2–3 molecules of SRII clearly showed a light-induced photocycle. Single molecules of SRII showed a photocycle upon signal averaging over several illumination cycles.

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