Characterization of the MetR binding sites for the glyA gene of Escherichia coli.

AUTOR(ES)

Lorenz, E

RESUMO

Sequence analysis of the glyA control region of Escherichia coli identified two regions with homology to the consensus binding sequence for MetR, a lysR family regulatory protein. Gel shift assays and DNase I protection assays verified that both sites bind MetR. Homocysteine, a coregulator for MetR, increased MetR binding to the glyA control region. The MetR binding sites were cloned into the pBend2 vector. Although the DNA did not show any significant intrinsic bend, MetR binding resulted in a bending angle of about 33 degrees. MetR-induced bending was independent of homocysteine. To verify that the MetR binding sites play a functional role in glyA expression, site-directed mutagenesis was used to alter the two binding sites in a lambda glyA-lacZ gene fusion phage. Changing the binding sites toward the consensus MetR binding sequence caused an increase in glyA-lacZ expression. Changing either binding site away from the consensus sequence caused a decrease in expression, suggesting that both sites are required for normal glyA regulation.

Documentos Relacionados

• Regulation of the Escherichia coli glyA gene by the metR gene product and homocysteine.
• Regulation of the Escherichia coli glyA gene by the purR gene product.
• Escherichia coli metR mutants that produce a MetR activator protein with an altered homocysteine response.
• Characterization of a second MetR-binding site in the metE metR regulatory region of Salmonella typhimurium.
• Regulation of methionine synthesis in Escherichia coli: effect of the MetR protein on the expression of the metE and metR genes.