title: A bacterial proteorhodopsin proton pump in marine eukaryotes.
abstract: Proteorhodopsins are light-driven proton pumps involved in widespread phototrophy. Discovered in marine proteobacteria just 10 years ago, proteorhodopsins are now known to have been spread by lateral gene transfer across diverse prokaryotes, but are curiously absent from eukaryotes. In this study, we show that proteorhodopsins have been acquired by horizontal gene transfer from bacteria at least twice independently in dinoflagellate protists. We find that in the marine predator Oxyrrhis marina, proteorhodopsin is indeed the most abundantly expressed nuclear gene and its product localizes to discrete cytoplasmic structures suggestive of the endomembrane system. To date, photosystems I and II have been the only known mechanism for transducing solar energy in eukaryotes; however, it now appears that some abundant zooplankton use this alternative pathway to harness light to power biological functions.
authors.affiliation: Canadian Institute for Advanced Research, Botany Department, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
authors.forename: Claudio H
authors.initials: CH
authors.lastname: Slamovits
authors.forename: Noriko
authors.initials: N
authors.lastname: Okamoto
authors.forename: Lena
authors.initials: L
authors.lastname: Burri
authors.forename: Erick R
authors.initials: ER
authors.lastname: James
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Keeling
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D015153:Blotting, Western; D004141:Dinoflagellida / Q000235:genetics* / Q000378:metabolism; D020224:Expressed Sequence Tags; D005455:Fluorescent Antibody Technique; D022761:Gene Transfer, Horizontal / Q000235:genetics*; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D017433:Protein Structure, Secondary; D017494:Proton Pumps / Q000235:genetics / Q000378:metabolism*; D012243:Rhodopsin / Q000235:genetics / Q000378:metabolism*; D025604:Rhodopsins, Microbial; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D017494:Proton Pumps; D025604:Rhodopsins, Microbial; C413548:proteorhodopsin; D012243:Rhodopsin