Document Detail

Enantioselective uptake and degradation of the chiral herbicide dichlorprop [(RS)-2-(2,4-dichlorophenoxy)propanoic acid] by Sphingomonas herbicidovorans MH.
MedLine Citation:
PMID:  9642189     Owner:  NLM     Status:  MEDLINE    
Sphingomonas herbicidovorans MH was able to completely degrade both enantiomers of the chiral herbicide dichlorprop [(RS)-2-(2,4-dichlorophenoxy)propanoic acid], with preferential degradation of the (S) enantiomer over the (R) enantiomer. These results are in agreement with the recently reported enantioselective degradation of mecoprop [(RS)-2-(4-chloro-2-methylphenoxy)propanoic acid] by this bacterium (C. Zipper, K. Nickel, W. Angst, and H.-P. E. Kohler, Appl. Environ. Microbiol. 62:4318-4322, 1996). Uptake of (R)-dichlorprop, (S)-dichlorporp, and 2,4-D (2,4-dichlorophenoxyacetic acid) was inducible. Initial uptake rates of cells grown on the respective substrate showed substrate saturation kinetics with apparent affinity constants (Kt) of 108, 93, and 117 microM and maximal velocities (Vmax) of 19, 10, and 21 nmol min-1 mg of protein-1 for (R)-dichlorprop, (S)-dichlorprop, and 2,4-D, respectively. Transport of (R)-dichlorprop, (S)-dichlorprop, and 2,4-D was completely inhibited by various uncouplers and by nigericin but was only marginally inhibited by valinomycin and by the ATPase inhibitor N,N'-dicyclohexylcarbodiimine. Experiments on the substrate specificity of the putative transport systems revealed that (R)-dichlorprop uptake was inhibited by (R)-mecoprop but not by (S)-mecoprop, (S)-dichlorprop, or 2,4-D. On the other hand, the (S)-dichlorprop transport was inhibited by (S)-mecoprop but not by (R)-mecoprop, (R)-dichlorprop, or 2,4-D. These results provide evidence that the first step in the degradation of dichlorprop, mecoprop, and 2,4-D by S. herbicidovorans is active transport and that three inducible, proton gradient-driven uptake systems exist: one for (R)-dichlorprop and (R)-mecoprop, another for (S)-dichlorprop and (S)-mecoprop, and a third for 2,4-D.
C Zipper; M Bunk; A J Zehnder; H P Kohler
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of bacteriology     Volume:  180     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  1998 Jul 
Date Detail:
Created Date:  1998-07-27     Completed Date:  1998-07-27     Revised Date:  2013-04-18    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  3368-74     Citation Subset:  IM    
Swiss Federal Institute for Environmental Science and Technology, Zürich, Switzerland.
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MeSH Terms
2,4-Dichlorophenoxyacetic Acid / analogs & derivatives*,  metabolism
2-Methyl-4-chlorophenoxyacetic Acid / analogs & derivatives,  metabolism
Adenosine Triphosphate / metabolism
Biodegradation, Environmental
Biological Transport
Carbon Radioisotopes
Flavobacterium / metabolism*
Models, Biological
Reg. No./Substance:
0/Carbon Radioisotopes; 56-65-5/Adenosine Triphosphate; 93-65-2/mecoprop; 94-74-6/2-Methyl-4-chlorophenoxyacetic Acid; 94-75-7/2,4-Dichlorophenoxyacetic Acid; J7YV2RKO6Q/dichlorprop

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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