MOAR, A GENE THAT ENCODES A POSITIVE REGULATOR OF THE MONOAMINE REGULON IN KLEBSIELLA-AEROGENES

We cloned and sequenced a Klaebsiella aerogenes gene (moaR) for activa tion of arylsulfatase synthesis by tyramine. This gene was cloned by c omplementation of a K. aerogenes mutant in which tyramine fails to rel ieve the arylsulfatase repression caused by sulfur compounds. The moaR gene also activated induction of the synthesis of both tyramine oxida se and the 30-kDa protein that is specifically induced by high concent rations of tyramine or catecholamines. The moaR gene on the chromosome of the wild-type strain of K. aerogenes was disrupted by homologous r ecombination with a plasmid containing the inactivated moaR. The resul tant mutant showed the same phenotype as previously isolated atsT muta nt strains that are negative for the derepressed synthesis of arylsulf atase. In this mutant strain, tyramine also failed to induce the synth esis of tyramine oxidase or the production of a 30-kDa protein. The mo aR gene is capable of encoding a protein of 26,238 Da. The putative Mo aR protein has a helix-turn-helix motif in its C terminus. Thus, it se ems likely that the MoaR protein regulates the operons by binding to t he regulatory region of the monoamine regulon. The MoaR protein is sub ject to autogenous control, which was shown by use of a moaR'-lacZ tra nscriptional fusion.