title: The CarO rhodopsin of the fungus Fusarium fujikuroi is a light-driven proton pump that retards spore germination.
abstract: Rhodopsins are membrane-embedded photoreceptors found in all major taxonomic kingdoms using retinal as their chromophore. They play well-known functions in different biological systems, but their roles in fungi remain unknown. The filamentous fungus Fusarium fujikuroi contains two putative rhodopsins, CarO and OpsA. The gene carO is light-regulated, and the predicted polypeptide contains all conserved residues required for proton pumping. We aimed to elucidate the expression and cellular location of the fungal rhodopsin CarO, its presumed proton-pumping activity and the possible effect of such function on F. fujikuroi growth. In electrophysiology experiments we confirmed that CarO is a green-light driven proton pump. Visualization of fluorescent CarO-YFP expressed in F. fujikuroi under control of its native promoter revealed higher accumulation in spores (conidia) produced by light-exposed mycelia. Germination analyses of conidia from carO(-) mutant and carO(+) control strains showed a faster development of light-exposed carO(-) germlings. In conclusion, CarO is an active proton pump, abundant in light-formed conidia, whose activity slows down early hyphal development under light. Interestingly, CarO-related rhodopsins are typically found in plant-associated fungi, where green light dominates the phyllosphere. Our data provide the first reliable clue on a possible biological role of a fungal rhodopsin.
authors.affiliation: Department of Genetics, Faculty of Biology, University of Seville, E-41012 Seville, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: García-Martínez
authors.affiliation: Department of Biotechnology and Biophysics, Biocenter, Julius Maximilian University Würzburg, D-97074 Würzburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Brunk
authors.affiliation: Department of Genetics, Faculty of Biology, University of Seville, E-41012 Seville, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Avalos
authors.affiliation: Department of Biotechnology and Biophysics, Biocenter, Julius Maximilian University Würzburg, D-97074 Würzburg, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Terpitz
mesh_terms: D000595:Amino Acid Sequence; D015139:Blotting, Southern; D002264:Carboxylic Acids / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000528:radiation effects; D015169:Colony Count, Microbial; D003624:Darkness; D055724:Electrophysiological Phenomena; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D005670:Fusarium / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects*; D005942:Gluconates / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008027:Light; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D017494:Proton Pumps / Q000737:chemistry / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry / Q000378:metabolism*; D013172:Spores, Fungal / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects
chemical_list: D002264:Carboxylic Acids; D005656:Fungal Proteins; D005942:Gluconates; D007477:Ions; D017494:Proton Pumps; D011993:Recombinant Fusion Proteins; D012243:Rhodopsin