A Klebsiella aerogenes moaEF operon is controlled by the positive MoaR regulator of the monoamine regulon.

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.