title: Genome streamlining in a cosmopolitan oceanic bacterium.
abstract: The SAR11 clade consists of very small, heterotrophic marine alpha-proteobacteria that are found throughout the oceans, where they account for about 25% of all microbial cells. Pelagibacter ubique, the first cultured member of this clade, has the smallest genome and encodes the smallest number of predicted open reading frames known for a free-living microorganism. In contrast to parasitic bacteria and archaea with small genomes, P. ubique has complete biosynthetic pathways for all 20 amino acids and all but a few cofactors. P. ubique has no pseudogenes, introns, transposons, extrachromosomal elements, or inteins; few paralogs; and the shortest intergenic spacers yet observed for any cell.
authors.affiliation: Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA. steve.giovannoni@oregonstate.edu
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Giovannoni
authors.forename: H James
authors.initials: HJ
authors.lastname: Tripp
authors.forename: Scott
authors.initials: S
authors.lastname: Givan
authors.forename: Mircea
authors.initials: M
authors.lastname: Podar
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Vergin
authors.forename: Damon
authors.initials: D
authors.lastname: Baptista
authors.forename: Lisa
authors.initials: L
authors.lastname: Bibbs
authors.forename: Jonathan
authors.initials: J
authors.lastname: Eads
authors.forename: Toby H
authors.initials: TH
authors.lastname: Richardson
authors.forename: Michiel
authors.initials: M
authors.lastname: Noordewier
authors.forename: Michael S
authors.initials: MS
authors.lastname: Rappé
authors.forename: Jay M
authors.initials: JM
authors.lastname: Short
authors.forename: James C
authors.initials: JC
authors.lastname: Carrington
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Mathur
mesh_terms: D020561:Alphaproteobacteria / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001482:Base Composition; D005075:Biological Evolution; D002244:Carbon / Q000378:metabolism; D019295:Computational Biology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D021901:DNA, Intergenic; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010710:Phosphates / Q000378:metabolism; D010802:Phylogeny; D012623:Seawater / Q000382:microbiology*; D012641:Selection, Genetic; D012808:Sigma Factor / Q000235:genetics; D013940:Thymidylate Synthase / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D021901:DNA, Intergenic; D026901:Membrane Transport Proteins; D010710:Phosphates; D012808:Sigma Factor; D002244:Carbon; D013940:Thymidylate Synthase