title: Evolutionary origin of the Rhodobacter sphaeroides specialized RpoN sigma factors.
abstract: Gene duplication and horizontal gene transfer (HGT) are two events that enable the generation of new genes. Rhodobacter sphaeroides (WS8 and 2.4.1 strains) has four copies of the rpoN gene that are not functionally interchangeable. Until now, this is the only example of specialization of this sigma factor. In this work, we aimed to determine whether the multiple copies of this gene originated from HGT or through gene duplication. Our results suggest a multiplication origin of the different rpoN copies that occurred after the Rhodobacter clade separated. Functional tests indicate that the specialization of the rpoN genes is not restricted to R. sphaeroides. We propose that the rpoN copy involved in nitrogen fixation is the ancestral gene and that the other rpoN genes have acquired new specificities.
authors.affiliation: Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México City, México.
authors.forename: Clelia
authors.initials: C
authors.lastname: Domenzain
authors.forename: Laura
authors.initials: L
authors.lastname: Camarena
authors.forename: Aurora
authors.initials: A
authors.lastname: Osorio
authors.forename: Georges
authors.initials: G
authors.lastname: Dreyfus
authors.forename: Sebastian
authors.initials: S
authors.lastname: Poggio
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D018628:Gene Dosage; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D010802:Phylogeny; D012242:Rhodobacter sphaeroides / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D012808:Sigma Factor