title: Closing the gaps on the viral photosystem-I psaDCAB gene organization.
abstract: Marine photosynthesis is largely driven by cyanobacteria, namely Synechococcus and Prochlorococcus. Genes encoding for photosystem (PS) I and II reaction centre proteins are found in cyanophages and are believed to increase their fitness. Two viral PSI gene arrangements are known, psaJF→C→A→B→K→E→D and psaD→C→A→B. The shared genes between these gene cassettes and their encoded proteins are distinguished by %G + C and protein sequence respectively. The data on the psaD→C→A→B gene organization were reported from only two partial gene cassettes coming from Global Ocean Sampling stations in the Pacific and Indian oceans. Now we have extended our search to 370 marine stations from six metagenomic projects. Genes corresponding to both PSI gene arrangements were detected in the Pacific, Indian and Atlantic oceans, confined to a strip along the equator (30°N and 30°S). In addition, we found that the predicted structure of the viral PsaA protein from the psaD→C→A→B organization contains a lumenal loop conserved in PsaA proteins from Synechococcus, but is completely absent in viral PsaA proteins from the psaJF→C→A→B→K→E→D gene organization and most Prochlorococcus strains. This may indicate a co-evolutionary scenario where cyanophages containing either of these gene organizations infect cyanobacterial ecotypes biogeographically restricted to the 30°N and 30°S equatorial strip.
authors: Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel.
authors: Sheila
authors: S
authors: Roitman
authors: Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel.
authors: José
authors: J
authors: Flores-Uribe
authors: Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel.
authors: Alon
authors: A
authors: Philosof
authors: Department of Biology, San Diego State University, San Diego, CA, USA.
authors: Ben
authors: B
authors: Knowles
authors: Department of Biology, San Diego State University, San Diego, CA, USA.
authors: Forest
authors: F
authors: Rohwer
authors: Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ, USA.
authors: J Cesar
authors: JC
authors: Ignacio-Espinoza
authors: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA.
authors: Matthew B
authors: MB
authors: Sullivan
authors: Departament of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain.
authors: Francisco M
authors: FM
authors: Cornejo-Castillo
authors: Departament of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain.
authors: Pablo
authors: P
authors: Sánchez
authors: Departament of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, Barcelona, Spain.
authors: Silvia G
authors: SG
authors: Acinas
authors: Microbial and Environmental Genomics Group, J Craig Venter Institute, San Diego, CA, USA.
authors: Chris L
authors: CL
authors: Dupont
authors: Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel.
authors: Oded
authors: O
authors: Béjà
mesh_terms: D000595:Amino Acid Sequence; D059001:Aquatic Organisms / Q000235:genetics / Q000378:metabolism; D001267:Atlantic Ocean; D001435:Bacteriophages / Q000235:genetics*; D005075:Biological Evolution; D023061:Gene Order; D005814:Genes, Viral / Q000235:genetics; D019156:Indian Ocean; D056186:Metagenomics; D010140:Pacific Ocean; D010788:Photosynthesis / Q000235:genetics*; D045331:Photosystem I Protein Complex / Q000235:genetics*; D045332:Photosystem II Protein Complex / Q000235:genetics; D048929:Prochlorococcus / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D046940:Synechococcus / Q000235:genetics* / Q000378:metabolism / Q000821:virology
chemical_list: D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex