Download MendeleyRegulation of a phage defence island by RptR, a novel repressor that controls restriction-modification systems in diverse bacteria.
Zhang, Y., Schuller, M., Ahel, I., Blower, T.R., Exley, R.M., Tang, C.M.(2025) Nucleic Acids Res 53
- PubMed: 40650974
- DOI: https://doi.org/10.1093/nar/gkaf645
- Primary Citation of Related Structures:
9R2Z - PubMed Abstract:
Bacteria encode a panoply of defence systems to overcome phage infection. In recent years, over 100 defence systems have been identified, with the majority of these found co-localized in defence islands. Although there has been much progress in understanding the mechanisms of anti-phage defence employed by bacteria, far less is known about their regulation before and during phage infection. Here, we describe RptR (RMS-proximal transcriptional regulator), a small transcriptional regulator of a defence island in enteropathogenic Escherichia coli composed of a toxin-antitoxin system, DarTG2, embedded within a Type I restriction-modification system (RMS). We determined the molecular structure of a RptR homodimer and, using transcriptional reporter and in vitro DNA binding assays, show that RptR represses the promoter of the defence island by binding to a series of three direct repeats in the promoter. Furthermore, we demonstrate, using the structural models of RptR validated with electrophoretic mobility shift assays, that the minimal RptR binding site is a 6-bp palindrome, TAGCTA. Both RptR and its binding site are highly conserved across diverse bacterial genomes with a strong genetic association with Type I RMS, highlighting the role of RptR as a novel regulatory component of an important mechanism for anti-phage defence in bacteria.
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom.
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