The CytR repressor antagonizes cyclic AMP-cyclic AMP receptor protein activation of the deoCp2 promoter of Escherichia coli K-12.

AUTOR(ES)

Søgaard-Andersen, L

RESUMO

We have investigated the regulation of the Escherichia coli deoCp2 promoter by the CytR repressor and the cyclic AMP (cAMP) receptor protein (CRP) complexed to cAMP. Promoter regions controlled by these two proteins characteristically contain tandem cAMP-CRP binding sites. Here we show that (i) CytR selectively regulated cAMP-CRP-dependent initiations, although transcription started from the same site in deoCp2 in the absence or presence of cAMP-CRP; (ii) deletion of the uppermost cAMP-CRP target (CRP-2) resulted in loss of CytR regulation, but had only a minor effect on positive control by the cAMP-CRP complex; (iii) introduction of point mutations in either CRP target resulted in loss of CytR regulation; and (iv) regulation by CytR of deletion mutants lacking CRP-2 could be specifically reestablished by increasing the intracellular concentration of CytR. These findings indicate that both CRP targets are required for efficient CytR repression of deoCp2. Models for the action of CytR are discussed in light of these findings.

Documentos Relacionados

• Cyclic AMP-cyclic AMP receptor protein as a repressor of transcription of the spf gene of Escherichia coli.
• Control mechanism of the Escherichia coli K-12 cell cycle is triggered by the cyclic AMP-cyclic AMP receptor protein complex.
• Identification of the nucleotide sequence recognized by the cAMP-CRP dependent CytR repressor protein in the deoP2 promoter in E. coli.
• On the action of the cyclic AMP-cyclic AMP receptor protein complex at the Escherichia coli lactose and galactose promoter regions.
• Nucleotide sequence of the CytR regulatory gene of E. coli K-12.