9R2Z

RptR transcriptional repressor

Summary for 9R2Z

• Entry DOI: 10.2210/pdb9r2z/pdb
• Descriptor: Transcription factor (3 entities in total)
• Functional Keywords: transcriptional regulator, dna binding, repressor, helical, dna binding protein
• Biological source: Escherichia coli O127:H6 str. E2348/69; More
• Total number of polymer chains: 2
• Total formula weight: 17975.50

Authors

Zhang, Y.,Schuller, M.,Ahel, I.,Blower, T.R.,Exley, R.M.,Tang, C.M. (deposition date: 2025-05-01, release date: 2025-07-23)

Primary citation

Zhang, Y.,Schuller, M.,Ahel, I.,Blower, T.R.,Exley, R.M.,Tang, C.M.
Regulation of a phage defence island by RptR, a novel repressor that controls restriction-modification systems in diverse bacteria.
Nucleic Acids Res., 53:-, 2025

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.

PubMed: 40650974
DOI: 10.1093/nar/gkaf645

Experimental method

X-RAY DIFFRACTION (1.3 Å)