title: Phylogenetic analysis of substrate-binding subunits in an osmoprotectant system.
abstract: Substrate-binding subunits are important components of the solute importation system, known as the osmoprotectant system, which consists of a membrane protein belonging to the ABC superfamily. These molecules recognize specific substrates that have different physiological roles in prokaryotes, i.e., roles that contribute to the survival of these organisms in environments with high concentrations of salt. Using the MEGA software, this study performed a phylogenetic analysis of 431 nucleotide sequences of these subunits, orthologous to each other, collected from the http://www.genome.jp/kegg/ database. This analysis allowed phylogenetic trees to be generated, clearly demonstrating that there was horizontal transfer of some genes through sharing by different organisms. Furthermore, two probable ancestral sequences were generated that showed homology with permeases that transport choline, glycine betaine, and carnitine, which are trimethylamines currently present in various prokaryotes. Therefore, this system probably arose in prokaryotic organisms with the basic function of capturing nutrients, and by performing this basal function and being shared with other organisms, it was fixed in the genome. However, because of prokaryote habitat diversification, this system contributed decisively to the adaptation of these organisms to different environments, especially environments that had a high salt concentration, thus acting as an osmoprotection system, which is how they are currently categorized.
authors.affiliation: Laborátorio de Genética Evolutiva Paulo Leminsk, Departamento de Biologia Molecular, Universidade Federal da Paraíba, João Pessoa, PB, Brasil coutinho8178@hotmail.com.
authors.forename: T J D
authors.initials: TJ
authors.lastname: Coutinho
authors.forename: N F
authors.initials: NF
authors.lastname: Rodrigues
authors.forename: S T
authors.initials: ST
authors.lastname: Farias
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001419:Bacteria / Q000145:classification / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011485:Protein Binding; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D055049:Salt Tolerance / Q000235:genetics*; D013379:Substrate Specificity
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D021122:Protein Subunits