Regulation of Enzyme Synthesis in the Bacteria: A Comparative and Evolutionary Study

Clarke, Paul

doi:10.1007/978-1-4684-3417-0_4

Cited by 4 publications

(3 citation statements)

References 188 publications

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“…The definition of constitutive states that the enzyme is neither inducible nor repressible. It is transcribed as a function of its promoter strength and the availability of RNA polymerase (6,11). We have demonstrated that ODC, ADC (28), and now AUH are subject to cAMP-mediated regulation which is independent of growth rate.…”

Section: Discussionmentioning

confidence: 93%

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Antagonistic transcriptional regulation of the putrescine biosynthetic enzyme agmatine ureohydrolase by cyclic AMP and agmatine in Escherichia coli

Satishchandran¹,

Boyle²

1984

J Bacteriol

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The putrescine biosynthetic enzyme agmatine ureohydrolase (AUH) (agmatinase; EC 3.5.3.11) catalyzes the conversion of agmatine to putrescine in Escherichia coli. The specific activity of AUH was determined in crude extracts prepared from wild-type strains and from strains with mutations in the adenylate cyclase gene (cya) or the cAMP receptor protein gene (crp) or both. In glucose minimal medium, a delta cya strain exhibited 70 to 90% higher AUH activity than a cya+ strain. Addition of 1 to 10 mM cAMP to cya+ and delta cya strains cultured in glucose repressed AUH activity in a dose-dependent manner. Addition of 1 to 10 mM cAMP to a delta crp strain failed to repress AUH activity. Addition of agmatine resulted in a three- to fourfold induction of AUH in delta cya and delta crp strains. This induction could be blocked by the addition of chloramphenicol. Simultaneous additions of various proportions of cAMP and agmatine resulted in reduced levels of induction and repression of AUH activity. This antagonistic regulation was shown to be exerted by independent mechanisms since AUH activity could be induced by agmatine in a delta crp strain supplemented with cAMP. These results suggest that both agmatine and cAMP antagonistically regulate AUH activity at the level of transcription. In minimal medium supplemented with 1 mM putrescine, the strains did not exhibit repression of AUH activity. In contrast, in minimal medium supplemented with 1 mM ornithine or arginine, cya+ or delta cya strains exhibited induced AUH activity as a result of conversion of these substrates to agmatine. Further experiments in vitro demonstrated that the effects observed with cAMP, agmatine, and arginine were not post-translationally mediated.

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Section: Discussionmentioning

confidence: 93%

“…Since ornithine levels in the cell would be depleted 200- FIG. 6. Effect of chloramphenicol on the induction of AUH by agmatine in the wild-type and the cya mutant strain of E. coli.…”

Section: Methodsmentioning

confidence: 99%