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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Alphaproteobacteria / classification
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Alphaproteobacteria / genetics*
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Alphaproteobacteria / isolation & purification
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Alphaproteobacteria / physiology
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism
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Base Composition
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Biological Evolution
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Carbon / metabolism
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Computational Biology
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DNA, Bacterial / chemistry
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DNA, Bacterial / genetics
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DNA, Intergenic
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Gene Expression Regulation, Bacterial
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Genes, Bacterial
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Genome, Bacterial*
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Membrane Transport Proteins / genetics
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Membrane Transport Proteins / metabolism
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Molecular Sequence Data
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Oceans and Seas
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Phosphates / metabolism
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Phylogeny
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Seawater / microbiology*
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Selection, Genetic
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Sigma Factor / genetics
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Thymidylate Synthase / genetics
Substances
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Bacterial Proteins
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DNA, Bacterial
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DNA, Intergenic
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Membrane Transport Proteins
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Phosphates
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Sigma Factor
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Carbon
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Thymidylate Synthase