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

Science (New York, N.Y.) | Sep 15, 2000

http://www.ncbi.nlm.nih.gov/pubmed/10988064

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 RIS Download

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