title: Environmentally directed mutations in the dehalogenase system of Pseudomonas putida strain PP3.
abstract: Favourable mutations involving the two dehalogenases (DehI and DehII) of Pseudomonas putida PP3 and derivative strains containing the cloned gene for DehI (dehI) occurred in response to specific environmental conditions, namely: starvation conditions; the presence of dehalogenase substrates (halogenated alkanoic acids--HAAs) which were toxic to P. putida; and/or the presence of a potential growth substrate. Fluctuation tests showed that these mutations were environmentally directed by the presence of HAAs. The mutations were associated with complex DNA rearrangements involving the movement of dehI located on a transposon DEH. Some mutations resulted in switching off the expression of either one or both of the dehalogenases, events which were effective in protecting P. putida from toxic compounds in its growth environment. Other mutations partially restored P. putida's dehalogenating capability under conditions where toxic substrates were absent. Restoration of the capability to untilize HAAs was favoured when normal growth substrates were present in the environment.
authors.affiliation: School of Pure and Applied Biology, University of Wales College of Cardiff, UK.
authors.forename: A W
authors.initials: AW
authors.lastname: Thomas
authors.forename: J
authors.initials: J
authors.lastname: Lewington
authors.forename: S
authors.initials: S
authors.lastname: Hope
authors.forename: A W
authors.initials: AW
authors.lastname: Topping
authors.forename: A J
authors.initials: AJ
authors.lastname: Weightman
authors.forename: J H
authors.initials: JH
authors.lastname: Slater
mesh_terms: D003470:Culture Media; D004251:DNA Transposable Elements; D003999:Dichloroacetic Acid / Q000494:pharmacology*; D004351:Drug Resistance / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D015321:Gene Rearrangement / Q000187:drug effects / Q000235:genetics; D006867:Hydrolases / Q000037:antagonists & inhibitors / Q000235:genetics*; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D011422:Propionates / Q000494:pharmacology*; D016958:Pseudomonas putida / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*
chemical_list: D003470:Culture Media; D004251:DNA Transposable Elements; D011422:Propionates; D003999:Dichloroacetic Acid; D006867:Hydrolases; C029658:propionic acid