A bacterial proteorhodopsin proton pump in marine eukaryotes

• Published in: Nature communications Vol. 2; no. 1; p. 183
• Main Authors: Keeling, Patrick J, Slamovits, Claudio H, Okamoto, Noriko, Burri, Lena, James, Erick R
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08.02.2011; Nature Publishing Group
• Subjects: 631/158/2446; 631/326/41/2535; 631/45/49/1142; 639/638/439/943; Amino Acid Sequence; Base Sequence; Biological Evolution; Blotting, Western; Dinoflagellida - genetics; Dinoflagellida - metabolism; Expressed Sequence Tags; Fluorescent Antibody Technique; Gene Transfer, Horizontal - genetics; Humanities and Social Sciences; Likelihood Functions; Models, Genetic; Molecular Sequence Data; multidisciplinary; Phylogeny; Protein Structure, Secondary; Proton Pumps - genetics; Proton Pumps - metabolism; Rhodopsin - genetics; Rhodopsin - metabolism; Rhodopsins, Microbial; Science; Science (multidisciplinary); Sequence Alignment; Sequence Analysis, DNA; Species Specificity
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms1188

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. Proteorhodopsin is used by prokaryotes to generate energy from light. In this study, the authors describe a prokaryote-to-eukaryote horizontal gene transfer of a bacterial proteorhodopsin gene to dinoflagellates, suggesting that these eukaryotes can also use proteorhodopsin to obtain light and produce energy.