TY - JOUR T1 - Phylogenetic and Phenotypic Characterization of the Energy-taxis Receptor Aer in <em>Pseudomonas</em> JF - bioRxiv DO - 10.1101/081455 SP - 081455 AU - Sean C. Booth AU - Raymond J. Turner Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/12/17/081455.abstract N2 - Chemotaxis allows bacteria to sense gradients in their environment and respond by directing their swimming. Aer is a receptor that, instead of responding to a specific chemoattractant, allows bacteria to sense cellular energy production and move towards favourable environments. In Pseudomonas, the number of apparent Aer homologs differed between the only two species it had been characterized in, P. aeruginosa and P. putida. Here we combined bioinformatic approaches with deletional mutagenesis in P. pseudoalcaligenes KF707 to further characterize Aer. It was determined that the number of Aer homologs varies between 0-4 throughout the Pseudomonas genus, and they were phylogenetically classified into 5 subgroups. We also used sequence analysis to show that these homologous receptors differ not in the ligand binding or signal transduction domains, but in the region in between. The most prevalent homolog was thus differentiated from Escherichia coli Aer by its different domain architecture. Genetic analysis also indicated that some Aer homologs have likely been subject to horizontal transfer. P. pseudoalcaligenes KF707 was unique among species for having three Aer homologs as well as the distinct chemoreceptor Aer-2. Phenotypic characterization in this species showed the most prevalent homolog was key, but not essential for energy-taxis. This study demonstrates that energy-taxis in Pseudomonas varies between species and provides a new naming convention and associated phylogenetic details for Aer chemoreceptors.Importance Energy-taxis enables Pseudomonas to swim towards favourable environments through sensing its cellular energy state via the receptor ‘Aer’. In Escherichia coli there is only one version of this gene but Pseudomonads appeared to have multiple. Here we show that there are 5 different homologs in Pseudomonas and that individual species can have between zero and four Aer homologs. These homologs do not differ in their ligand-binding region or signal transduction module, but in the region between them. Only one homolog has a HAMP domain like E. coli Aer, making the other homologs interesting among chemoreceptors for not having this domain. In P. pseudoalcaligenes KF707, which has a unique complement of Aer homologs and other chemoreceptors, all Aer homologs influenced energy-taxis. ER -