1887

Abstract

SeqA protein is a major negative regulator of chromosomal DNA replication acting by sequestration, and thus inactivation, of newly formed regions. However, other activities of this protein have been discovered recently, one of which is regulation of transcription. SeqA has been demonstrated to be a specific transcription factor acting at bacteriophage promoters , and . While SeqA-mediated stimulation of and occurs by facilitating functions of another transcription activator protein, cII, a mechanism for stimulation of remains largely unknown. Here, it has been demonstrated that two GATC sequences, located 82 and 105 bp downstream of the transcription start site, are necessary for this stimulation both and . SeqA-mediated activation of was as effective on a linear DNA template as on a supercoiled one, indicating that alterations in DNA topology are not likely to facilitate the SeqA effect. transcription analysis demonstrated that the most important regulatory effect of SeqA in transcription occurs after open complex formation, namely during promoter clearance. SeqA did not influence the appearance and level of abortive transcripts or the pausing during transcription elongation. Interestingly, SeqA is one of few known prokaryotic transcription factors which bind downstream of the regulated promoter and still act as transcription activators.

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2006-10-01
2020-03-30
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