Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 6/3/1999
Publication Date: N/A
Technical Abstract: The bacterial aerotactic response allows motile cells to move to a more favorable environment in response to changing oxygen availability or redox conditions. In this study, we cloned a gene involved in aerotaxis by the motile gram negative bacterium Pseudomonas putida. The aerotaxis receptor gene, aer, was identified by screening a P. putida PRS2000 genomic library with a probe from the highly conserved domain of transducer-like proteins. The role of aer in aerotaxis was established by disruption of the chromosomal aer gene with a kanamycin resistance cassette. The resulting P. putida mutant was defective in aerotaxis when observed in a capillary assay. Wild-type P. putida formed an aerotactic cluster packed tightly at the air/liquid interface. In contrast, the aer mutant formed a diffuse band at a distance from the meniscus. Wild-type aer, provided in trans, complemented the aer mutant to a normal aerotactic response. These results sdemonstrate that the aer gene encodes a protein required for aerotaxis. The 521 aa P. putida Aer open reading frame is similar over its entire length to the aerotaxis (energy taxis) protein of Escherichia coli but has the highest identity (40%) to an open reading frame of unknown function encoded by Tn1721. The deduced amino-terminal sequence of Aer in P. putida is similar to redox-sensing regulatory proteins and contains a conserved PAS signaling domain, which in other proteins is involved in sensing oxygen, redox, or light. The carboxy terminus of Aer is similar to methyl-accepting chemotaxis proteins and contains the highly conserved domain present in chemotactic transducers.