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 cel ls carried a plasmid (pAS123) that included the arylsulfatase operon ( atsBA). Deletion analysis showed that the region essential for inducti on of the 30-kDa protein was located within a 2.0-kb cloned segment do wnstream of the atsBA operon. The nucleotide (nt) sequence of the 2.0- kb fragment revealed two open reading frames (ORFs), moaE and moaF. Tr anscription from a putative promoter of moaE was induced by the additi on of tyramine, and the moaF gene was co-transcribed from this monoami ne-inducible Ka promoter. The deduced Ka MoaE protein was homologous t o insect-type alcohol dehydrogenase. The sequence of the 18 amino acid s 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 moaE F operon.