title: Diversity of viral photosystem-I psaA genes.
abstract: Marine photosynthesis is one of the major contributors to the global carbon cycle and the world's oxygen supply. This process is largely driven by cyanobacteria, namely Synechococcus and Prochlorococcus. Genes encoding photosystem-II (PSII) reaction center proteins are found in many cyanophage genomes, and are expressed during the infection of their hosts. On the basis of metagenomics, cyanophage photosystem-I (PSI) gene cassettes were recently discovered with two gene arrangements psaJF→C→A→B→K→E→D and psaD→C→A→B. It was suggested that the horizontal transfer of PSII and PSI genes is increasing phage fitness. To better understand their diversity, we designed degenerate primers to cover a wide diversity of organisms, and using PCR we targeted the psaC→A arrangement, which is unique to cyanophages cassettes. We examined viral concentrates from four islands in the Pacific Ocean and found samples containing the psaC→A arrangement. Analyses of the amplified viral psaA gene revealed six subgroups varying in their level of similarity and %G+C content, suggesting that the diversity of cyanophage PSI genes is greater than originally thought.
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Gur
authors.initials: G
authors.lastname: Hevroni
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Hagay
authors.initials: H
authors.lastname: Enav
authors.affiliation: Department of Biology, San Diego State University, San Diego, CA, USA.
authors.forename: Forest
authors.initials: F
authors.lastname: Rohwer
authors.affiliation: Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Oded
authors.initials: O
authors.lastname: Béjà
mesh_terms: D001482:Base Composition; D005787:Gene Frequency; D023061:Gene Order; D005814:Genes, Viral / Q000235:genetics*; D014644:Genetic Variation; D056186:Metagenomics; D008969:Molecular Sequence Data; D010140:Pacific Ocean; D010788:Photosynthesis / Q000235:genetics; D045331:Photosystem I Protein Complex / Q000235:genetics*; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D048929:Prochlorococcus / Q000235:genetics*; D046940:Synechococcus / Q000235:genetics*
chemical_list: D045331:Photosystem I Protein Complex