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We cloned and sequenced a KiebsieUla aerogenes gene (moaR) for activation of arylsulfatase synthesis by tyramine. This gene was cloned by complementation of a K. aerogenes mutant in which tyramine fails to relieve the arylsulfatase repression caused by sulfur compounds. The moaR gene also activated induction of the synthesis of both tyramine oxidase and the 30-kDa protein that is specifically induced by high concentrations of tyramine or catecholamines. The moaR gene on the chromosome of the wild-type strain ofK. aerogenes was disrupted by homologous recombination with a plasmid containing the inactivated moaR. The resultant mutant

A 30-kDa protein accumulated upon induction by a high concentration of tyramine or dopamine in cells of Klebsiella aerogenes (Ka). These cells carried a plasmid (pAS123) that included the arylsulfatase operon (atsBA). Deletion analysis showed that the region essential for induction of the 30-kDa protein was located within a 2.0-kb cloned segment downstream of the atsBA operon. The nucleotide (nt) sequence of the 2.0-kb fragment revealed two open reading frames (ORFs), moaE and moaF. Transcription from a putative promoter of moaE was induced by the addition of tyramine, and the moaF gene was co-transcribed from this monoamine-inducible Ka promoter. The deduced Ka MoaE protein was homologous to insect-type alcohol dehydrogenase. The sequence of the 18 amino acids from the N-terminus of the purified 30-kDa protein agreed with that deduced from the nt sequence of moaF. Using a Ka strain with a mutant moaR gene, we found that MoaR, that acts as the positive regulator of the monoamine regulon, also acts as the positive regulator of the moaEF operon.

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