title: Genome sequence of the cyanobacterium Prochlorococcus marinus SS120, a nearly minimal oxyphototrophic genome.
abstract: Prochlorococcus marinus, the dominant photosynthetic organism in the ocean, is found in two main ecological forms: high-light-adapted genotypes in the upper part of the water column and low-light-adapted genotypes at the bottom of the illuminated layer. P. marinus SS120, the complete genome sequence reported here, is an extremely low-light-adapted form. The genome of P. marinus SS120 is composed of a single circular chromosome of 1,751,080 bp with an average G+C content of 36.4%. It contains 1,884 predicted protein-coding genes with an average size of 825 bp, a single rRNA operon, and 40 tRNA genes. Together with the 1.66-Mbp genome of P. marinus MED4, the genome of P. marinus SS120 is one of the two smallest genomes of a photosynthetic organism known to date. It lacks many genes that are involved in photosynthesis, DNA repair, solute uptake, intermediary metabolism, motility, phototaxis, and other functions that are conserved among other cyanobacteria. Systems of signal transduction and environmental stress response show a particularly drastic reduction in the number of components, even taking into account the small size of the SS120 genome. In contrast, housekeeping genes, which encode enzymes of amino acid, nucleotide, cofactor, and cell wall biosynthesis, are all present. Because of its remarkable compactness, the genome of P. marinus SS120 might approximate the minimal gene complement of a photosynthetic organism.
authors.affiliation: Station Biologique, Unité Mixte de Recherche 7127, Centre National de la Recherche Scientifique et Université Paris 6, BP74, 29682 Roscoff Cedex, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Dufresne
authors.forename: Marcel
authors.initials: M
authors.lastname: Salanoubat
authors.forename: Frédéric
authors.initials: F
authors.lastname: Partensky
authors.forename: François
authors.initials: F
authors.lastname: Artiguenave
authors.forename: Ilka M
authors.initials: IM
authors.lastname: Axmann
authors.forename: Valérie
authors.initials: V
authors.lastname: Barbe
authors.forename: Simone
authors.initials: S
authors.lastname: Duprat
authors.forename: Michael Y
authors.initials: MY
authors.lastname: Galperin
authors.forename: Eugene V
authors.initials: EV
authors.lastname: Koonin
authors.forename: Florence
authors.initials: F
authors.lastname: Le Gall
authors.forename: Kira S
authors.initials: KS
authors.lastname: Makarova
authors.forename: Martin
authors.initials: M
authors.lastname: Ostrowski
authors.forename: Sophie
authors.initials: S
authors.lastname: Oztas
authors.forename: Catherine
authors.initials: C
authors.lastname: Robert
authors.forename: Igor B
authors.initials: IB
authors.lastname: Rogozin
authors.forename: David J
authors.initials: DJ
authors.lastname: Scanlan
authors.forename: Nicole
authors.initials: N
authors.lastname: Tandeau de Marsac
authors.forename: Jean
authors.initials: J
authors.lastname: Weissenbach
authors.forename: Patrick
authors.initials: P
authors.lastname: Wincker
authors.forename: Yuri I
authors.initials: YI
authors.lastname: Wolf
authors.forename: Wolfgang R
authors.initials: WR
authors.lastname: Hess
mesh_terms: D000222:Adaptation, Physiological; D001482:Base Composition; D002473:Cell Wall / Q000378:metabolism; D002734:Chlorophyll / Q000096:biosynthesis; D002952:Citric Acid Cycle; D000458:Cyanobacteria / Q000235:genetics* / Q000378:metabolism; D004260:DNA Repair; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D015321:Gene Rearrangement; D016680:Genome, Bacterial; D008386:Marine Biology; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000096:biosynthesis; D009792:Oceans and Seas; D016366:Open Reading Frames; D010788:Photosynthesis / Q000235:genetics*; D010839:Phytoplankton / Q000235:genetics*; D015398:Signal Transduction
chemical_list: D004269:DNA, Bacterial; D009711:Nucleotides; D002734:Chlorophyll