title: Evolution and functional characterization of the RH50 gene from the ammonia-oxidizing bacterium Nitrosomonas europaea.
abstract: The family of ammonia and ammonium channel proteins comprises the Amt proteins, which are present in all three domains of life with the notable exception of vertebrates, and the homologous Rh proteins (Rh50 and Rh30) that have been described thus far only in eukaryotes. The existence of an RH50 gene in bacteria was first revealed by the genome sequencing of the ammonia-oxidizing bacterium Nitrosomonas europaea. Here we have used a phylogenetic approach to study the evolution of the N. europaea RH50 gene, and we show that this gene, probably as a component of an integron cassette, has been transferred to the N. europaea genome by horizontal gene transfer. In addition, by functionally characterizing the Rh50(Ne) protein and the corresponding knockout mutant, we determined that NeRh50 can mediate ammonium uptake. The RH50(Ne) gene may thus have replaced functionally the AMT gene, which is missing in the genome of N. europaea and may be regarded as a case of nonorthologous gene displacement.
authors.affiliation: INSERM, U845, Paris F-75015, France.
authors.forename: Baya
authors.initials: B
authors.lastname: Cherif-Zahar
authors.forename: Anne
authors.initials: A
authors.lastname: Durand
authors.forename: Ingo
authors.initials: I
authors.lastname: Schmidt
authors.forename: Nabila
authors.initials: N
authors.lastname: Hamdaoui
authors.forename: Ivan
authors.initials: I
authors.lastname: Matic
authors.forename: Mike
authors.initials: M
authors.lastname: Merrick
authors.forename: Giorgio
authors.initials: G
authors.lastname: Matassi
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D019143:Evolution, Molecular; D017353:Gene Deletion; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism*; D043370:Nitrosomonas europaea / Q000235:genetics* / Q000502:physiology*; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; D000641:Ammonia