Thiol ester-linked p-coumaric acid as a new photoactive prosthetic group in a protein with rhodopsin-like photochemistry

Biochemistry. 1994 Nov 29;33(47):13959-62. doi: 10.1021/bi00251a001.


A number of Eubacteria contain a photoactive yellow protein which has a photosensory function in negative phototaxis. It has been proposed that the cofactor responsible for the intense yellow color of this protein is retinal [McRee, D. E., et al. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 6533-6537]. This would make it the first eubacterial rhodopsin. Here we report the chemical structure of this chromophoric group to be p-coumaric acid, which is covalently bound to a unique cysteine in the apoprotein via a thiol ester bond, and thus not retinal. This makes PYP the first example of a protein containing p-coumaric acid, a metabolite previously found only in plants, as a prosthetic group and establishes the photoactive yellow proteins as a new type of photochemically active receptor molecule.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatiaceae / chemistry
  • Chromatography, High Pressure Liquid
  • Coumaric Acids / chemistry*
  • Cysteine / chemistry
  • Disulfides / chemistry
  • Dithiothreitol / pharmacology
  • Esters / chemistry
  • Hydrogen-Ion Concentration
  • Magnetic Resonance Spectroscopy
  • Photochemistry
  • Propionates
  • Rhodopsin / chemistry*
  • Sodium Hydroxide / pharmacology
  • Sulfhydryl Compounds / chemistry


  • Coumaric Acids
  • Disulfides
  • Esters
  • Propionates
  • Sulfhydryl Compounds
  • Sodium Hydroxide
  • Rhodopsin
  • trans-3-(4'-hydroxyphenyl)-2-propenoic acid
  • Cysteine
  • Dithiothreitol