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Mol Microbiol. 2015 Aug;97(3):488-501. doi: 10.1111/mmi.13045. Epub 2015 May 26.

Specific gamma-aminobutyrate chemotaxis in pseudomonads with different lifestyle.

Author information

1
Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Prof. Albareda, 1, 18008, Granada, Spain.
2
Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université Rouen, 55 rue Saint Germain, 27000, Evreux, France.
3
Laboratorio de Ecología Molecular Microbiana, Centro de Investigaciones en Ciencias Microbiológicas-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, 72570, Puebla, Mexico.
4
Max Planck Institute for Terrestrial Microbiology & LOEWE Research Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch Strasse 10, D-35043, Marburg, Germany.
5
Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany.

Abstract

The PctC chemoreceptor of Pseudomonas aeruginosa mediates chemotaxis with high specificity to gamma-aminobutyric acid (GABA). This compound is present everywhere in nature and has multiple functions, including being a human neurotransmitter or plant signaling compound. Because P. aeruginosa is ubiquitously distributed in nature and able to infect and colonize different hosts, the physiological relevance of GABA taxis is unclear, but it has been suggested that bacterial attraction to neurotransmitters may enhance virulence. We report the identification of McpG as a specific GABA chemoreceptor in non-pathogenic Pseudomonas putida KT2440. As with PctC, GABA was found to bind McpG tightly. The analysis of chimeras comprising the PctC and McpG ligand-binding domains fused to the Tar signaling domain showed very high GABA sensitivities. We also show that PctC inactivation does not alter virulence in Caenorhabditis elegans. Significant amounts of GABA were detected in tomato root exudates, and deletion of mcpG reduced root colonization that requires chemotaxis through agar. The C. elegans data and the detection of a GABA receptor in non-pathogenic species indicate that GABA taxis may not be related to virulence in animal systems but may be of importance in the context of colonization and infection of plant roots by soil-dwelling pseudomonads.

PMID:
25921834
DOI:
10.1111/mmi.13045
[Indexed for MEDLINE]
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