areABC genes determine the catabolism of aryl esters in Acinetobacter sp strain ADP1

Acinetobacter sp, strain ADP1 is able to grow on a range of esters of aroma tic alcohols, converting them to the corresponding aromatic carboxylic acid s by the sequential action of three inducible enzymes: an ar Area-encoded e sterase, an areB-encoded benzyl alcohol dehydrogenase, and an areC-encodcd benzaldehyde dehydrogenase, The are genes, adjacent to each other on the ch romosome and transcribed in the order areCBA, were located 3.5 kbp upstream of benK, benK, encoding a permease implicated in benzoate uptake, is at on e end of the ben-cat supraoperonic cluster for benzoate catabolism by the b eta-ketoadipate pathway. Two open reading frames which may encode a transcr iptional regulator, areR, and a porin, benP, separate benK from areC, Each are gene was individually expressed to high specific activity in Escherichi a call, The relative activities against different substrates of the cloned enzymes were, within experimental error, identical to that of wild-type Aci netobacter sp, strain ADP1 grown on either benzyl acetate, benzyl alcohol, or 4-hydroxybenzyl alcohol as the carbon source. The substrate preferences of all three enzymes were broad, encompassing a range of substituted aromat ic compounds and in the case of the AreA esterase, different carboxylic aci ds, The areA, areB, and areC genes were individually disrupted on the chrom osome by insertion of a kanamycin resistance cassette, and the rates at whi ch the resultant strains utilized substrates of the aryl ester catabolic pa thway were severely reduced as determined by growth competitions between th e mutant and wild-type strains.