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Modification dependent restriction endonucleases (MDREs) restrict modified DNA, typically with limited sequence specificity (∼2-4 bp). Here, we focus on MDREs that have an SRA and/or SBD (sulfur binding domain) fused to an HNH endonuclease domain, cleaving cytosine modified or phosphorothioated (PT) DNA. We independently characterized the SBD-SRA-HNH endonuclease ScoMcrA, which preferentially cleaves 5hmC modified DNA. We report five SBD-HNH endonucleases, all recognizing GpsAAC/GpsTTC sequence and cleaving outside with a single nucleotide 3' stagger: EcoWI (N7/N6), Ksp11411I (N5/N4), Bsp305I (N6/N4-5), Mae9806I [N(8-10)/N(8-9)], and Sau43800I [N(8-9)/N(7-8)]. EcoWI and Bsp305I are more specific for PT modified DNA in Mg buffer, and promiscuous with Mn. Ksp11411I is more PT specific with Ni. EcoWI and Ksp11411I cleave fully- and hemi-PT modified oligos, while Bsp305I cleaves only fully modified ones. EcoWI forms a dimer in solution and cleaves more efficiently in the presence of two modified sites. In addition, we demonstrate that EcoWI PT-dependent activity has biological function: EcoWI expressing cells restrict dnd GpsAAC modified plasmid strongly, and GpsGCC DNA weakly. This work establishes a framework for biotechnology applications of PT-dependent restriction endonucleases (PTDRs).
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http://dx.doi.org/10.3389/fmicb.2020.01960 | DOI Listing |
Nucleic Acids Res
September 2025
School of Microbiology, University College Cork, Cork, T12 Y337, Ireland.
The genomes of 43 distinct lactococcal strains were reconstructed by a combination of long- and short-read sequencing, resolving the plasmid complement and methylome of these strains. The genomes comprised 43 chromosomes of approximately 2.5 Mb each and 269 plasmids ranging from 2 to 211 kb (at an average occurrence of 6 per strain).
View Article and Find Full Text PDFNat Microbiol
September 2025
The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.
Restriction-modification (R-M) systems protect against phage infection by detecting and degrading invading foreign DNA. However, like many prokaryotic anti-phage defences, R-M systems pose a major risk of autoimmunity, exacerbated by the presence of hundreds to thousands of potential cleavage sites in the bacterial genome. Pseudomonas aeruginosa strains experience the temporary inactivation of restriction endonucleases following growth at high temperatures, but the reason and mechanisms for this phenomenon are unknown.
View Article and Find Full Text PDFPhilos Trans R Soc Lond B Biol Sci
September 2025
Department of Biosciences, Durham University, Durham DH1 3LE, UK.
Bacteriophages (phages), viral predators of bacteria, generate selection pressure that causes bacteria to evolve defence systems. Type I, II and III restriction enzymes cleave incoming non-modified phage DNAs. Phages have evolved to defend against these restriction systems by modifying their DNA so that they are no longer suitable substrates.
View Article and Find Full Text PDFPhilos Trans R Soc Lond B Biol Sci
September 2025
Molecular Microbiology and Structural Biochemistry (MMSB), CNRS UMR 5086, Université Claude Bernard Lyon 1, 69367 Lyon, France.
Bacterial resistance to bacteriophages (phages) relies on two primary strategies: preventing phage attachment and blocking post-attachment steps. These post-attachment mechanisms are mediated by diverse defence systems, including DNA-degrading systems such as restriction-modification and CRISPR-Cas, along with abortive infection systems that induce cell death or dormancy. Computational analyses suggest that bacterial genomes encode multiple defence systems, which may act synergistically to enhance phage resistance.
View Article and Find Full Text PDFTalanta
August 2025
School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, 807, Taiwan; Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, 807, Taiwan; Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung, 807, Taiwan. Ele
The identification of single-nucleotide variations remains a significant challenge in genetic research due to their high similarity to wild-type DNA sequences. Many conventional approaches rely on sophisticated instrumentation or costly reagents, which limits their accessibility and broad application. To overcome these limitations, a novel detection strategy grounded in the well-established principle of restriction fragment length polymorphism (RFLP) was developed.
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