title: eggNOG: automated construction and annotation of orthologous groups of genes.
abstract: The identification of orthologous genes forms the basis for most comparative genomics studies. Existing approaches either lack functional annotation of the identified orthologous groups, hampering the interpretation of subsequent results, or are manually annotated and thus lag behind the rapid sequencing of new genomes. Here we present the eggNOG database ('evolutionary genealogy of genes: Non-supervised Orthologous Groups'), which contains orthologous groups constructed from Smith-Waterman alignments through identification of reciprocal best matches and triangular linkage clustering. Applying this procedure to 312 bacterial, 26 archaeal and 35 eukaryotic genomes yielded 43 582 course-grained orthologous groups of which 9724 are extended versions of those from the original COG/KOG database. We also constructed more fine-grained groups for selected subsets of organisms, such as the 19 914 mammalian orthologous groups. We automatically annotated our non-supervised orthologous groups with functional descriptions, which were derived by identifying common denominators for the genes based on their individual textual descriptions, annotated functional categories, and predicted protein domains. The orthologous groups in eggNOG contain 1 241 751 genes and provide at least a broad functional description for 77% of them. Users can query the resource for individual genes via a web interface or download the complete set of orthologous groups at http://eggnog.embl.de.
authors.affiliation: European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: Lars Juhl
authors.initials: LJ
authors.lastname: Jensen
authors.forename: Philippe
authors.initials: P
authors.lastname: Julien
authors.forename: Michael
authors.initials: M
authors.lastname: Kuhn
authors.forename: Christian
authors.initials: C
authors.lastname: von Mering
authors.forename: Jean
authors.initials: J
authors.lastname: Muller
authors.forename: Tobias
authors.initials: T
authors.lastname: Doerks
authors.forename: Peer
authors.initials: P
authors.lastname: Bork
mesh_terms: D000818:Animals; D030541:Databases, Genetic / Q000592:standards / Q000706:statistics & numerical data; D005796:Genes; D023281:Genomics; D020407:Internet; D010802:Phylogeny; D011506:Proteins / Q000145:classification / Q000235:genetics* / Q000502:physiology; D011786:Quality Control; D014584:User-Computer Interface
chemical_list: D011506:Proteins