Utilization of 3-chloro-2-methylbenzoic acid by Pseudomonas cepacia MB2 through the meta fission pathway.
Pseudomonas cepacia MB2 grew on 3-chloro-2-methylbenzoate as a sole carbon source by metabolism through the meta fission pathway with the subsequent liberation of chloride. meta pyrocatechase activity in cell extracts was induced strongly by 3-chloro-2-methylbenzoate, but not by nongrowth analogs 4- or 5-chloro-2-methylbenzoate. Although rapid turnover of metabolites precluded direct identification, a mutant strain MB2-G5 lacking meta pyrocatechase activity produced 4-chloro-3-methylcatechol when incubated with 3-chloro-2-methylbenzoate. The catecholic product, confirmed by nuclear magnetic resonance and mass spectral analyses, produced a transient meta fission product (lambda max = 391 nm) from cell extracts of the wild-type MB2 strain. Further confirmation of meta pyrocatechase activity was noted by conversion of 4-chlorocatechol to 2-hydroxy-5-chloromuconic semialdehyde, which was not further metabolized. In contrast to 3-chlorocatechol, which was not metabolized and is known to generate suicidal products, 4-chlorocatechols do not generate acyl halides. Thus, further metabolism of the ring fission products is governed in strain MB2 by their suitability as substrates for the hydrolase.
Higson
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FK
Department of Soil and Environmental Sciences, University of California, Riverside 92521.
Focht
D D
DD
D016956:Burkholderia cepacia / Q000254:growth & development / Q000378:metabolism*; D050557:Catechol 2,3-Dioxygenase; D002396:Catechols / Q000378:metabolism; D002723:Chlorobenzoates / Q000378:metabolism*; D049308:Dioxygenases; D010105:Oxygenases / Q000378:metabolism
D002396:Catechols; D002723:Chlorobenzoates; C076377:3-chloro-2-methylbenzoic acid; D010105:Oxygenases; D049308:Dioxygenases; D050557:Catechol 2,3-Dioxygenase