Mechanism for transcriptional action of cyclic AMP in Escherichia coli: entry into DNA to disrupt DNA secondary structure.

AUTOR(ES)

Ebright, R H

RESUMO

Binding analysis with purified bacterial receptor distinguishes two structural domains in cyclic AMP (cAMP). The first, the cyclic phosphate and furanose, constitutes a binding domain. This region is bound tightly to the receptor. The rest of cAMP is not bound; the adenine moiety of cAMP is exposed. Unlike binding, activity of cAMP requires the adenine moiety. To be active, cAMP must have in domain II the base adenine--specifically, its Watson--Crick atoms N-1 and N-6. Analysis of indoleacetic acid, a compound able to replace cAMP at the L-arabinose operon, indicates a similar distinction between binding and active domains. To be active, the indole must have substitution (carboxyl or amide) electronically comparable to the cAMP N-1 and N-6. On this basis, we propose a detailed mechanism for action of cAMP (or indoleacetic acid) in Escherichia coli. We propose that the exposed adenine of cAMP enters into the DNA. The adenine's N-1 and N-6 form hydrogen bonds to a thymine in DNA. This interaction destabilizes the DNA. It enhances transcription. Marked similarities indicate an identical mechanism for the steroid hormones in eukaryotes.

Documentos Relacionados

• Mutational specificity of UV light in Escherichia coli: indications for a role of DNA secondary structure.
• Microcin 15m from Escherichia coli: mechanism of antibiotic action.
• Circular dichroism and DNA secondary structure.
• On the action of the cyclic AMP-cyclic AMP receptor protein complex at the Escherichia coli lactose and galactose promoter regions.
• Control mechanism of the Escherichia coli K-12 cell cycle is triggered by the cyclic AMP-cyclic AMP receptor protein complex.