title: Proteorhodopsin phototrophy promotes survival of marine bacteria during starvation.
abstract: Proteorhodopsins are globally abundant photoproteins found in bacteria in the photic zone of the ocean. Although their function as proton pumps with energy-yielding potential has been demonstrated, the ecological role of proteorhodopsins remains largely unexplored. Here, we report the presence and function of proteorhodopsin in a member of the widespread genus Vibrio, uncovered through whole-genome analysis. Phylogenetic analysis suggests that the Vibrio strain AND4 obtained proteorhodopsin through lateral gene transfer, which could have modified the ecology of this marine bacterium. We demonstrate an increased long-term survival of AND4 when starved in seawater exposed to light rather than held in darkness. Furthermore, mutational analysis provides the first direct evidence, to our knowledge, linking the proteorhodopsin gene and its biological function in marine bacteria. Thus, proteorhodopsin phototrophy confers a fitness advantage to marine bacteria, representing a novel mechanism for bacterioplankton to endure frequent periods of resource deprivation at the ocean's surface.
authors.affiliation: Marine Microbiology, School of Natural Sciences, Linnaeus University, Kalmar, Sweden.
authors.forename: Laura
authors.initials: L
authors.lastname: Gómez-Consarnau
authors.forename: Neelam
authors.initials: N
authors.lastname: Akram
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Lindell
authors.forename: Anders
authors.initials: A
authors.lastname: Pedersen
authors.forename: Richard
authors.initials: R
authors.lastname: Neutze
authors.forename: Debra L
authors.initials: DL
authors.lastname: Milton
authors.forename: José M
authors.initials: JM
authors.lastname: González
authors.forename: Jarone
authors.initials: J
authors.lastname: Pinhassi
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival / Q000502:physiology*; D002874:Chromosome Mapping; D016680:Genome, Bacterial; D008027:Light; D008969:Molecular Sequence Data; D052817:Phototrophic Processes; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000145:classification / Q000235:genetics; D012243:Rhodopsin / Q000235:genetics / Q000378:metabolism*; D025604:Rhodopsins, Microbial; D012623:Seawater / Q000382:microbiology*; D014733:Vibrio / Q000145:classification / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D012336:RNA, Ribosomal, 16S; D025604:Rhodopsins, Microbial; C413548:proteorhodopsin; D012243:Rhodopsin