title: Natural history of ABC systems: not only transporters.
abstract: In recent years, our understanding of the functioning of ABC (ATP-binding cassette) systems has been boosted by the combination of biochemical and structural approaches. However, the origin and the distribution of ABC proteins among living organisms are difficult to understand in a phylogenetic perspective, because it is hard to discriminate orthology and paralogy, due to the existence of horizontal gene transfer. In this chapter, I present an update of the classification of ABC systems and discuss a hypothetical scenario of their evolution. The hypothetical presence of ABC ATPases in the last common ancestor of modern organisms is discussed, as well as the additional possibility that ABC systems might have been transmitted to eukaryotes, after the two endosymbiosis events that led to the constitution of eukaryotic organelles. I update the functional information of selected ABC systems and introduce new families of ABC proteins that have been included recently into this vast superfamily, thanks to the availability of high-resolution three-dimensional structures.
authors.affiliation: Institut Pasteur, Unité des Membranes Bactériennes, Département de Microbiologie, Institut Pasteur, 25 Rue du Dr Roux, 75724 Paris Cedex 15, France. elie.dassa@pasteur.fr
authors.forename: Elie
authors.initials: E
authors.lastname: Dassa
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000502:physiology*; D005075:Biological Evolution; D010802:Phylogeny
chemical_list: D018528:ATP-Binding Cassette Transporters