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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/4065

Title: The Rhizobium etli opt operon is required for symbiosis and stress resistance
Authors: Vos, K.
Braeken, K.
Fauvart, M.
Ndayizeye, M.
Verhaert, J.
Zachurzok, S.
Michiels, J.
Issue Date: 2007
Citation: ENVIRONMENTAL MICROBIOLOGY, 9(7). p. 1665-1674
Abstract: Rhizobium etli is a Gram-negative root-colonizing soil bacterium capable of fixing nitrogen while living in symbiosis with its leguminous host Phaseolus vulgaris. A genome-wide screening for R. etli symbiotic mutants revealed a R. etli operon encoding an oligopeptide ABC-transporter (Opt), two redA homologous genes and one redB gene. Expression analysis showed this opt operon to be transcribed both under free-living and symbiotic conditions and expression levels were demonstrated to be growth-phase-dependent. Plants nodulated by R. etli opt mutants showed a reduced symbiotic nitrogen fixation activity (approximately 50% reduction). Growth experiments with opt mutants in the presence of oligopeptides as the sole nitrogen source confirmed the involvement of the opt genes in oligopeptide uptake. Further phenotypic analysis of the opt mutants revealed them to display an enhanced resistance to the oligopeptide antibiotic bacitracin, an increased susceptibility to the beta-lactam antibiotic ampicillin and a decreased osmotolerance. In conclusion, our results demonstrate that the opt operon plays a crucial role during symbiosis and stress resistance.
Notes: Katholieke Univ Leuven, Ctr Microbial & Plant Genet, B-3001 Heverlee, Belgium. Univ Hasselt, Dept Basic Med Sci, B-3590 Diepenbeek, Belgium.MICHIELS, J, Katholieke Univ Leuven, Ctr Microbial & Plant Genet, B-3001 Heverlee, Belgium.jan.michiels@biw.kuleuven.be
URI: http://hdl.handle.net/1942/4065
DOI: 10.1111/j.1462-2920.2007.01284.x
ISI #: 000247124200006
ISSN: 1462-2912
Category: A1
Type: Journal Contribution
Validation: ecoom, 2008
Appears in Collections: Research publications

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