2-PHENYLETHYLAMINE CATABOLISM BY ESCHERICHIA-COLI K-12 - GENE ORGANIZATION AND EXPRESSION

A gene encoding phenylacetaldehyde dehydrogenase (PAD), the enzyme inv olved together with a copper-topaquinone-containing amine oxidase in t he initial steps of 2-phenylethylamine catabolism, was located at 31.1 min on the Escherichia coli K-12 genetic map. It was immediately adja cent to the gene encoding the amine oxidase but transcribed in the opp osite direction. The purified PAD acted almost equally well on phenyla cetaldehyde, 4-hydroxyphenylacetaldehyde and 3,4-dihydroxyphenylacetal dehyde. It had a subunit size of 54 kDa and its deduced amino acid seq uence was approximately 40 % identical to various eukaryotic and proka ryotic aldehyde dehydrogenases. A third gene encoding a positive regul atory protein required for expression of the amine oxidase and PAD gen es was located next to the PAD gene. A gene previously located in this position was reported to encode a second amine oxidase but this was n ot confirmed. The nucleotide sequence from 1447 to 1450 kb on the E. c oli K-12 physical map has been determined.