DNA sequence determinants of LexA-induced DNA bending.
The LexA repressor from Escherichia coli induces DNA bending upon interaction with the two overlapping operators which regulate the transcription of the colicin A encoding gene caa. Both caa operators harbor T-tracts adjacent to their recognition motifs. These tracts have been suggested to be especially favorable for the promotion of LexA-induced DNA bending. Here we show that this is indeed the case, since disruption of the TTTT-tract adjacent to operator O1 by the replacement of the two central thymine bases by AA, GA or CG markedly reduces LexA-induced DNA bending. Simple A.T-richness in this position is thus not sufficient to promote full LexA-induced bending, albeit a TAAT sequence is always more efficient to promote bending than those sequences containing one or two C/G base pairs.
Lloubès
R
R
Centre de Biochimie et de Biologie Moléculaire, Marseille, France.
Lazdunski
C
C
Granger-Schnarr
M
M
Schnarr
M
M
D001426:Bacterial Proteins / Q000378:metabolism* / Q000494:pharmacology; D001482:Base Composition; D001483:Base Sequence; D003087:Colicins / Q000235:genetics; D004247:DNA / Q000737:chemistry*; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation / Q000187:drug effects; D009876:Operon; D012097:Repressor Proteins / Q000494:pharmacology*; D015183:Restriction Mapping; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D003087:Colicins; D004247:DNA; D012097:Repressor Proteins; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein