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Title (Primary) Adaptation of the herbicide-degrading strain Delftia acidovorans MC1 through carbonylation of RdpA as key enzyme
Author Leibeling, S.; Taubert, M.; Seifert, J.; von Bergen, M.; Harms, H.; Müller, R.H.
Journal Journal of Biotechnology
Year 2010
Department UMB; PROTEOM
Volume 150
Issue Suppl. 1
Page From S262
Page To S263
Language englisch
Keywords Carbonylation; Phenoxyalkanoate Herbicides; RdpA; Mass Spectrometry

A huge spectrum of compounds is released to the environment by the chemical industry and the consumers. This raises the question how microorganisms as the said main degradative counterforce tackle the problem of adapting to structures that often exhibit a xenobiotic character. Relevant environmental pollutants are phenoxyalkanoates like 2,4-dichlorophenoxyacetate (2,4-D) and (RS)-2-(2,4-dichlorophenoxy-)propionate ((RS)-2,4-DP) that have been applied as herbicides for about 70 years. The soil bacterium Delftia acidovorans MC1 is able to degrade these herbicides. One of the key enzymes, RdpA, is highly specific for the R-enantiomer of phenoxypropionate herbicides ((R)-2,4-DP) whereas it has very weak activity for corresponding phenoxyacetates (2,4-D). Adaptation was studied in mutant strains bearing only RdpA by analysing its changing enzyme activity after (i) starvation and (ii) addition of the unfavorable herbicide 2,4-D. Whereas starvation caused a loss in activity, the presence of 2,4-D raised the degradative capability for this herbicide. In both cases this was accompanied by a change in the enzyme pattern as made visible by 2D gel electrophoresis, showing RdpA variants with different isoelectric points (pI). As there is only one rdpA gene in the genome, they are likely to result from posttranslational modifications. We were able to identify carbonylation reactions as potential mechanism. This is exerted by reactive oxygen species (ROS), which are known side products of dioxygenase reactions. Starvation and adaptation to unfavourable substrates thereby lead to an increase of oxidative stress and thus an enhanced release of ROS. The physiological consequences of the adaptation were followed by monitoring changing enzyme activities. Furthermore we analysed the degree of carbonylation and identified the carbonylation sites using mass spectrometric analysis. Further investigations have to ensure the most interestingly hypothesis that carbonylation seems likely to be associated with a positive response instead of the reported adverse effects that are generally attributed to such modifications.
Persistent UFZ Identifier
Leibeling, S., Taubert, M., Seifert, J., von Bergen, M., Harms, H., Müller, R.H. (2010):
Adaptation of the herbicide-degrading strain Delftia acidovorans MC1 through carbonylation of RdpA as key enzyme
J. Biotechnol. 150 (Suppl. 1), S262 - S263