Interaction of bacteriophage lambda repressor with nonoperator DNA containing single-strand gaps.
In direct binding assays, purified lambdaind+ repressor displayed high affinity for nonoperator DNA containing single-strand gaps. Its affinity for this same DNA but completely double-stranded, nicked, or denatured was considerably lower. In contrast, purified lambdaind- repressor had 1/10th the affinity for the gapped DNA, a level comparable to that of purified lac repressor. In the presence of limiting amounts of ind+ repressor, nonoperator DNA containing gaps could be shown to compete effectively with lambda DNA for binding of repressor. A previous model of lambda induction [Sussman, R. & Ben-Zeev, H. (1975) Proc. Natl. Acad. Sci. USA 72, 1973--1976], based on the assumption that this phenomenon involves the binding of repressor to lesions in the host DNA, is reevaluated in the light of the data reported here.
D001665:Binding Sites; D001667:Binding, Competitive; D003090:Coliphages / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D005809:Genes, Regulator; D008242:Lysogeny; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000378:metabolism*; D014779:Virus Replication
D004277:DNA, Single-Stranded; D012097:Repressor Proteins; D014157:Transcription Factors