THE MONOAMINE REGULON INCLUDING SYNTHESES OF ARYLSULFATASE AND MONOAMINE-OXIDASE IN BACTERIA

Bacterial cells respond to monoamine compounds, such as tyramine, dopa mine, octopamine, or norepinephrine, and induce the syntheses of tyram ine oxidase encoded by tynA and monoamine oxidase encoded by maoA. The se monoamine compounds also derepress the synthesis of atsA-specified arylsulfatase that is repressed by sulfur compounds. These complex mec hanisms of regulons regulated by monoamine and sulfur compounds has be en analyzed by cloning and characterization of genes that are involved in the repression and derepression of the synthesis of arylsulfatase. The atsA gene forms an operon with the atsB gene, which encodes an ac tivator of the expression of atsA. The negative regulator gene for ary lsulfatase was found to code for dihydrofolate reductase (folA). The m aoA gene forms an operon with the maoC gene, which has similarity to a dehydrogenase involved in the tyramine metabolism. The moaF gene enco ding a 30-kDa protein, which is induced by tyramine, also forms an ope ron with the moaE gene. Finally, the moaR gene, which is induced by mo noamine, was found to play a central role in the positive regulation o f the expression of the monoamine regulon (moa) including the atsBA, m aoCA, moaEF, and tyn operons. The moaR expression is subject to autoge nous regulation and to cAMP-CRP control. The MoaR protein has a helix- turn-helix motif in its C terminus. Thus, the MoaR protein probably re gulates the operons by binding to the regulatory region of the moa reg ulon.