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We studied how DNA divergence between recombining DNAs and the mismatch repair system modulate the SOS response in Escherichia coli. The observed positive log-linear correlation between SOS induction and DNA divergence, and the negative correlation between SOS induction and frequency of recombination, suggest that the level of SOS induction precisely reflects the difficulty of RecA protein to initiate a productive strand exchange process. Our results suggest that the mismatch repair system could contribute to this SOS induction more by affecting the RecA-catalyzed homology search than by acting on mismatched recombination intermediates. The propensity of the recombination machinery to promote recombination between the blocks of sequences with the highest identity results in the increasing ratios of merodiploids (partial diploids) over genuine recombinants (homologous replacements) with increasing DNA divergence. We discuss the role of molecular mechanisms involved in the control of the recombination between diverged DNA sequences in the maintenance of genomic stability and genome evolution.
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http://dx.doi.org/10.1016/j.dnarep.2004.09.008 | DOI Listing |
Philos Trans R Soc Lond B Biol Sci
September 2025
University of Exeter Environment and Sustainability Institute, Penryn TR10 9FE, UK.
Bacteria evolve resistance against their phage foes with a wide range of resistance strategies whose costs and benefits depend on the level of protection they confer and on the costs for maintainance. can evolve resistance against its phage DMS either by surface mutations that prevent phage binding or through CRISPR-Cas immunity. CRISPR immunity carries an inducible cost whose exact origin is still unknown, and previous work suggested it stems from the inability of the CRISPR-Cas system to completely prevent phage DNA injection and subsequent gene expression before clearing the phage infection.
View Article and Find Full Text PDFEur J Intern Med
August 2025
Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy; Centre for Inflammatory Diseases, Monash University Department of Medicine, Monash Medical Centre, Melbourne, Australia. Electronic address:
Background: Subcutaneous immunoglobulin (SCIg) is a promising alternative to intravenous Ig (IVIg) for the treatment of idiopathic inflammatory myositis (IIM), thanks to its more favorable safety profile, reduced costs, and lower impact on patients' quality of life. We assessed the short- and long-term effectiveness and safety of recombinant human hyaluronidase-facilitated SCIg (hf-SCIg) in patients with IIM treated at different referral centers in Italy.
Methods: A multicenter, retrospective, real-life cohort study was conducted on consecutive adult patients diagnosed with IIM according to the EULAR/ACR criteria, treated with hf-SCIg for remission induction or maintenance.
PLoS Genet
September 2025
Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, United States of America.
Studies have shown that DNA damage repair systems, including homologous recombination (HR) and the SOS response, are important for fluoroquinolone (FQ) persistence of Escherichia coli, which has been the workhorse organism of persister research. We sought to explore whether those systems are also important for FQ persistence of Pseudomonas aeruginosa, a common cause of lung infections in cystic fibrosis patients, which can be treated with FQs such as ciprofloxacin (CIP). Notably, P.
View Article and Find Full Text PDFMutat Res Genet Toxicol Environ Mutagen
August 2025
Facultad Mexicana de Medicina, Universidad La Salle, CDMX, Mexico.
The SOS response contains a set of about 45 genes related to the repair or tolerance to DNA damage. These genes are normally blocked but when lesions upon the genetic material occur an SOS signal is generated allowing their expression. Most types of DNA lesions must be modified or processed to induce SOS.
View Article and Find Full Text PDFNucleic Acids Res
August 2025
MOE Key Laboratory of Biosystems Homeostasis & Protection, Institute of Biophysics, College of Life Sciences, Zhejiang University, Hangzhou 310016, China.
DNA-damage chemicals, including many antibiotics, often induce prophage induction and phage outbreaks within microbial communities, posing a significant threat to bacterial survival. Moraxellaceae strains are clinically relevant due to their remarkable resistance to antibiotics and radiation. However, the cellular-level regulation mechanisms that underlie their DNA damage response and anti-phage defense remain extensively unexplored.
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