Identification of a chemoreceptor that specifically mediates chemotaxis toward metabolizable purine derivatives.
Chemotaxis is an essential mechanism that enables bacteria to move toward favorable ecological niches. Escherichia coli, the historical model organism for studying chemotaxis, has five well-studied chemoreceptors. However, many bacteria with different lifestyle have more chemoreceptors, most of unknown function. Using a high throughput screening approach, we identified a chemoreceptor from Pseudomonas putida KT2440, named McpH, which specifically recognizes purine and its derivatives, adenine, guanine, xanthine, hypoxanthine and uric acid. The latter five compounds form part of the purine degradation pathway, permitting their use as sole nitrogen sources. Isothermal titration calorimetry studies show that these six compounds bind McpH-Ligand Binding Domain (LBD) with very similar affinity. In contrast, non-metabolizable purine derivatives (caffeine, theophylline, theobromine), nucleotides, nucleosides or pyrimidines are unable to bind McpH-LBD. Mutation of mcpH abolished chemotaxis toward the McpH ligands identified - a phenotype that is restored by complementation. This is the first report on bacterial chemotaxis to purine derivatives and McpH the first chemoreceptor described that responds exclusively to intermediates of a catabolic pathway, illustrating a clear link between metabolism and chemotaxis. The evolution of McpH may reflect a saprophytic lifestyle, which would have exposed the studied bacterium to high concentrations of purines produced by nucleic acid degradation.
Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008, Granada, Spain.
Matilde
M
Fernández
Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008, Granada, Spain.
Bertrand
B
Morel
Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008, Granada, Spain.
Andrés
A
Corral-Lugo
Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008, Granada, Spain.
Tino
T
Krell
D002633:Chemotaxis; D017353:Gene Deletion; D005816:Genetic Complementation Test; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D016958:Pseudomonas putida / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D011687:Purines / Q000378:metabolism*
D008565:Membrane Proteins; D011687:Purines