Antibacterial quinolones inhibit type II DNA topoisomerases by stabilizing covalent topoisomerase-DNA cleavage complexes, which are apparently transformed into double-stranded breaks by cellular processes such as replication. We used plasmid pBR322 and two-dimensional agarose gel electrophoresis to examine the collision of replication forks with quinolone-induced gyrase-DNA cleavage complexes in Escherichia coli. Restriction endonuclease-digested DNA exhibited a bubble arc with discrete spots, indicating that replication forks had been stalled. The most prominent spot depended upon the strong gyrase binding site of pBR322, providing direct evidence that quinolone-induced cleavage complexes block bacterial replication forks in vivo. We differentiated between stalled forks that do or do not contain bound cleavage complex by extracting DNA under different conditions. Resealing conditions allow gyrase to efficiently reseal the transient breaks within cleavage complexes, while cleavage conditions cause the latent breaks to be revealed. These experiments showed that some stalled forks did not contain a cleavage complex, implying that gyrase had dissociated in vivo and yet the fork had not restarted at the time of DNA isolation. Additionally, some branched plasmid DNA isolated under resealing conditions nonetheless contained broken DNA ends. We discuss a model for the creation of double-stranded breaks by an indirect mechanism after quinolone treatment.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1201555 | PMC |
| http://dx.doi.org/10.1111/j.1365-2958.2005.04638.x | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Rapid and sensitive detection of using multiple cross displacement amplification combined with CRISPR-Cas12a-based biosensing system.
Heliyon
January 2025
Department of Otorhinolaryngology Head and Neck Surgery, Children's Hospital Capital Institute of Pediatrics, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
(, Hi) is an opportunistic bacterium that colonizes the upper respiratory tract of humans and frequently causes meningitis, pneumonia, sepsis, and other severe infections in children. Early and accurate detection of is essential for effective diagnosis and treatment. In this study, we established a novel diagnostic method by integrating the CRISPR-Cas12a detection platform with multiple cross-displacement amplification (MCDA), termed the Hi-MCDA-CRISPR assay.
View Article and Find Full Text PDFArabidopsis conditional photosynthesis mutants abc1k1 and var2 accumulate partially processed thylakoid preproteins and are defective in chloroplast biogenesis.
Commun Biol
January 2025
Institute of biology, Plant Physiology Laboratory, Université de Neuchâtel, 2000, Neuchâtel, Switzerland.
Photosynthetic activity is established during chloroplast biogenesis. In this study we used 680 nm red light to overexcite Photosystem II and disrupt photosynthesis in two conditional mutants (var2 and abc1k1) which reversibly arrested chloroplast biogenesis. During biogenesis, chloroplasts import most proteins associated with photosynthesis.
View Article and Find Full Text PDFMechanistic insights and optimization of lignin depolymerization into aromatic monomers using vanadium-modified Dawson-type polyoxometalates.
Int J Biol Macromol
January 2025
Key Laboratory of Biomass Materials Science and Technology of Jilin Province, Beihua University, Binjiang East Road, Jilin City, Jilin Province, PR China; Collaborative Innovation Center of Forest Biomass Green Manufacturing of Jilin Province, Beihua University, Binjiang East Road, Jilin City, Jilin Province, PR China; Key Laboratory of Wooden Materials Science and Engineering of Jilin Province, Beihua University, Binjiang East Road, Jilin City, Jilin Province, PR China. Electronic address:
Lignin, as the largest renewable aromatic resource, has significant opportunities for producing high-value products via catalytic depolymerization. However, its complex structure and stable chemical bonds present challenges to its transformation. This study explores the catalytic depolymerization of lignin to aromatic monomers by means of Dawson-type phosphomolybdovanadate polyoxometalates (POMs), understanding the underlying mechanisms.
View Article and Find Full Text PDFPhotocatalyst-free formate-mediated C-O cleavage by the EDA complex and SCS strategy for the synthesis of diaryl 1,4-diketone in air.
Org Biomol Chem
January 2025
School of Life Science and Engineering, School of Chemistry, Southwest Jiaotong University, Chengdu, 610031, China.
Under mild visible light conditions, formates facilitate C-O cleavage the EDA complex and SCS strategy, yielding α-carbonyl alkyl radicals. These radicals then react with olefins under air conditions, leading to the synthesis of diaryl 1,4-dicarbonyl compounds. Mechanistic studies reveal that α-formyloxy ketone is generated by the reaction between α-brominated acetophenone and formates, followed by the formation of the EDA complex.
View Article and Find Full Text PDFStructural Conformation and the Binding of Factor VIII R2159C (FVIII-Ise) Mutated in the C1 Domain to Phospholipid.
Thromb Haemost
January 2025
Department of Pediatrics, Nara Medical University, Kashihara, Nara, Japan.
Background: We previously identified a factor (F)VIII molecular defect associated with an R2159C mutation in the C1 domain (named "FVIII-Ise") together with undetectable FVIII antigen (FVIII:Ag) levels measured by two-site sandwich ELISA using an anti-C2 domain alloantibody (alloAb). The patient had clinically mild hemophilia A, and his reduced FVIII:C correlated with FVIII:Ag measured by ELISA using monoclonal antibodies (mAbs) with A2 and A2/B domain epitopes, suggesting that the R2159C mutation modified C2 domain antigenicity.
Aim: To investigate functional and structural characteristics of the FVIII-R2159C mutant.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!