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Bacterial rhodopsin: evidence for a new type of phototrophy in the sea.

Extremely halophilic archaea contain retinal-binding integral membrane proteins called bacteriorhodopsins that function as light-driven proton pumps. So far, bacteriorhodopsins capable of generating a chemiosmotic membrane potential in response to light have been demonstrated only in halophilic archaea. We describe here a type of rhodopsin derived from bacteria that was discovered through genomic analyses of naturally occuring marine bacterioplankton. The bacterial rhodopsin was encoded in the genome of an uncultivated gamma-proteobacterium and shared highest amino acid sequence similarity with archaeal rhodopsins. The protein was functionally expressed in Escherichia coli and bound retinal to form an active, light-driven proton pump. The new rhodopsin exhibited a photochemical reaction cycle with intermediates and kinetics characteristic of archaeal proton-pumping rhodopsins. Our results demonstrate that archaeal-like rhodopsins are broadly distributed among different taxa, including members of the domain Bacteria. Our data also indicate that a previously unsuspected mode of bacterially mediated light-driven energy generation may commonly occur in oceanic surface waters worldwide.

Pubmed ID: 10988064


  • Béjà O
  • Aravind L
  • Koonin EV
  • Suzuki MT
  • Hadd A
  • Nguyen LP
  • Jovanovich SB
  • Gates CM
  • Feldman RA
  • Spudich JL
  • Spudich EN
  • DeLong EF


Science (New York, N.Y.)

Publication Data

September 15, 2000

Associated Grants

  • Agency: NHGRI NIH HHS, Id: HG01775-02S1
  • Agency: NIGMS NIH HHS, Id: R01GM27750

Mesh Terms

  • Aerobiosis
  • Amino Acid Sequence
  • Archaea
  • Bacteria
  • Bacterial Physiological Phenomena
  • Cloning, Molecular
  • Escherichia coli
  • Gammaproteobacteria
  • Molecular Sequence Data
  • Oceans and Seas
  • Photochemistry
  • Photosynthesis
  • Phylogeny
  • Phytoplankton
  • Protein Binding
  • Proton Pumps
  • Retinaldehyde
  • Rhodopsin
  • Water Microbiology