Gene order of the TOL catabolic plasmid upper pathway operon and oxidation of both toluene and benzyl alcohol by the xylA product

Journal Article · Fri Aug 01 00:00:00 EDT 1986 · J. Bacteriol.; (United States)

OSTI ID:6991525

Harayama, S; Leppik, R A; Rekik, M; Mermod, N; Lehrbach, P R; Reineke, W; Timmis, K N

TOL plasmid pWW0 specifies enzymes for the oxidative catabolism of toluene and xylenes. The upper pathway converts the aromatic hydrocarbons to aromatic carboxylic acids via corresponding alcohols and aldehydes and involves three enzymes: xylene oxygenase, benzyl alcohol dehydrogenase, and benzaldehyde dehydrogenase. The synthesis of these enzymes is positively regulated by the product of xylR. Determination of upper pathway enzyme levels in bacteria carrying Tn5 insertion mutant derivatives of plasmid pWW0-161 has shown that the genes for upper pathway enzymes are organized in an operon with the following order: promoter-xylC (benzaldehyde dehydrogenase gene(s))-xylA (xylene oxygenase gene(s))-xylB (benzyl alcohol dehydrogenase gene). Subcloning of the upper pathway genes in a lambda p/sub L/ promoter-containing vector and analysis of their expression in Escherichia coli K-12 confirmed this order. Two distinct enzymes were found to attack benzyl alcohol, namely, xylene oxygenase and benzyl alcohol dehydrogenase; and their catalytic activities were additive in the conversion of benzyl alcohol to benzaldehyde. The fact that benzyl alcohol is both a product and a substrate of xylene oxygenase indicates that this enzyme has a relaxed substrate specificity.

• Research Organization: Univ. of Geneva, Switzerland
• OSTI ID: 6991525
• Journal Information: J. Bacteriol.; (United States), Vol. 167:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CATABOLISM
GENE REGULATION
TOLUENE
XYLENES
BIOLOGICAL PATHWAYS
CLONING
ENZYME ACTIVITY
ESCHERICHIA COLI
GENE OPERONS
OXIDOREDUCTASES
PLASMIDS
PSEUDOMONAS
TRANSCRIPTION
ALKYLATED AROMATICS
AROMATICS
BACTERIA
CELL CONSTITUENTS
ENZYMES
HYDROCARBONS
METABOLISM
MICROORGANISMS
ORGANIC COMPOUNDS
550500* - Metabolism
550400 - Genetics