Demonstration of two operator elements in gal: in vitro repressor binding studies.
AUTOR(ES)
Majumdar, A
RESUMO
Genetic and DNA base sequence analyses of cis-dominant mutations that derepress the gal operon of Escherichia coli suggested the existence of two operator loci needed for gal repression. One (OE) is located immediately upstream to the two overlapping gal promoters and the other (OI) is inside the first structural gene. We have investigated the ability of wild-type and mutant OE and OI DNA sequences to bind to gal repressor. The repressor has been purified from cells containing a multicopy plasmid in which the repressor gene is brought under the control of phage lambda PL promoter. The DNA-repressor interactions are detected by the change in electrophoretic mobility of labeled DNA that accompanies its complex formation with repressor protein. The purified repressor shows concentration-dependent binding to both O+E and O+I but not to OEc and OIc sequences. These results authenticate the proposed operator role of the two homologous gal DNA control elements and thereby establish that the negative control of the gal operon requires repressor binding at both OE and OI, which are separated by greater than 90 base pairs.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=391867Documentos Relacionados
- Characterization of two mutations in the Escherichia coli galE gene inactivating the second galactose operator and comparative studies of repressor binding.
- Analysis of tet operator-TET repressor complexes by thermal denaturation studies.
- Two helix DNA binding motif of CAP found in lac repressor and gal repressor.
- Interaction of Gal repressor with inducer and operator: Induction of gal transcription from repressor-bound DNA
- Interaction between the lac operator and the lac repressor headpiece: fluorescence and circular dichroism studies.