Enzymes of agmatine degradation and the control of their synthesis in Klebsiella aerogenes

Abstract

The degradation of agmatine to succinate by K. aerogenes occurs in 5 steps. The enzyme catalyzing the 1st step, agmatinase, is induced by agmatine. The enzymes catalyzing the 2nd and 3rd steps, putrescine aminotransferase and 4-aminobutyraldehyde dehydrogenase, are induced by putrescine and also by their product, 4-aminobutyrate. The enzymes catalyzing the 4th and 5th steps, 4-aminobutyrate aminotransferase and succinate semialdehyde dehydrogenase, are induced by 4-aminobutyrate. This compound also serves as gratuitous inducer of the catabolic acetylornithine aminotransferase. The formation of the enzymes responsible for agmatine degradation is regulated not only by induction, but also by catabolite repression and activation by glutamine synthetase.