Open AccessCatabolism of aromatics in Pseudomonas putida U
Author(s) -
OLIVERA Elias R.,
REGLERO Angel,
MARTÍNEZBLANCO Honorina,
FERNÁNDEZMEDARDE Alberto,
MORENO Miguel A.,
LUENGO José M.
Publication year - 1994
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1994.tb18749.x
Subject(s) - pseudomonas putida , mutant , catabolism , phenylacetic acid , biochemistry , dna ligase , enzyme , strain (injury) , chemistry , gene , transposable element , point mutation , biology , anatomy
Phenylacetic acid (PhAcOH) and 4‐hydroxyphenylacetic acid (4HOPhAcOH) are catabolized in Pseudomonas putida U through two different pathways. Mutation carried out with the transposon Tn5 has allowed the isolation of several mutants which, unlike the parental strain, are unable to grow in chemically defined medium containing either PhAcOH or 4HOPhAcOH as the sole carbon source. Analysis of these strains showed that the ten mutants unable to grow in PhAcOH medium grew well in the one containing 4HOPhAcOH, whereas four mutants handicapped in the degradation of 4HOPhAcOH were all able to utilize PhAcOH. These results show that the degradation of these two aromatic compounds in P. putida U is not carried out as formerly believed through a single linear and common pathway, but by two unrelated routes. Identification of the blocked point in the catabolic pathway and analysis of the intermediate accumulated, showed that the mutants unable to utilize 4HOPhAcOH corresponded to two different groups: those blocked in the gene encoding 4‐hydroxyphenylacetic acid‐3‐hydroxylase; and those blocked in the gene encoding homoprotocatechuate‐2,3‐dioxygenase. Mutants unable to use PhAcOH as the sole carbon source have been also classified into two different groups: those which contain a functional PhAc‐CoA ligase protein; and those lacking this enzyme activity.