Project Details
Projekt
Dehalogenation of halogenated benzoic acids in denitrifying bacteria
Applicant
Professor Dr. Matthias Boll
Subject Area
Metabolism, Biochemistry and Genetics of Microorganisms
Term
from 2011 to 2018
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 171475307
Halogenated aromatics represent a widely distributed class of environmentally relevant compounds, which can be biologically degraded under both aerobic and anaerobic conditions. The anaerobic degradation has usually been associated with membrane-bound reductive dehalogenases, corrinoid-containing key enzymes of anaerobic organohalide respiration. In contrast, the complete oxidative degradation of halobenzoates in anaerobes has been reported in denitrifying, sulfate-reducing, Fe(III)-respiring and in anaerobic phototrophic bacteria. Although initial evidence has been obtained that in Rhodopseudomonas palustris the 3-Cl-benzoate degradation pathway proceeds via CoA-esters, including a reductive dehalogenation step, the dehalogenation reaction has thus far not been demonstrated in vitro. Reductive removal of the halogen atom from halobenzoyl-CoAs may be accomplished by a novel class of dehalogenases or by dearomatizing benzoyl-CoA reductases. In this project we will study the degradation of various halobenzoates in the denitrifying model organisms Thauera chlorobenzoica and Azoarcus evansii. The major objectives are: (i) determination of the substrate/product of the dehalogenation reactions by CoA-ester metabolome analysis and by the in vitro assays; (ii) characterization of the enzymatic dehalogenation process (kinetics, mechanism, stereochemical course, etc.); (iii) isolation/characterization of key enzymes involved in halobenzoate catabolism; and (iv) the determination of the minimal enzymatic prerequisites for growth on halobenzoates.
DFG Programme
Research Units
