Base excision repair (BER) is a conserved and ubiquitous pathway that is initiated by DNA glycosylases, which recognize and remove damaged or mismatched nucleobases, setting the stage for restoration of the correct DNA sequence by follow-on BER enzymes. DNA glycosylases employ a nucleotide-flipping step prior to cleavage of the N-glycosyl bond, and most exhibit slow release of the abasic DNA product and/or strong product inhibition. As such, studying the catalytic mechanism of these enzymes requires care in the design, execution, and interpretation of single- and multiple-turnover kinetics experiments, which is the topic of this chapter.
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http://dx.doi.org/10.1016/bs.mie.2017.03.016 | DOI Listing |
Nucleic Acids Res
January 2025
Guangdong Provincial Key Laboratory of Digestive Cancer Research, Digestive Diseases Center, Scientific Research Center, The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, Guangdong 518107, P.R. China.
CRISPR-Cas12a technology has transformative potential, but as its applications grow, enhancing its inherent functionalities is essential to meet diverse demands. Here, we reveal a regulatory mechanism for LbCas12a through direct repeat (DR) region 3' end modifications and de-modifications, which can regulate LbCas12a's cis- and trans-cleavage activities. We extensively explored the effects of introducing phosphorylation, DNA, photo-cleavable linker, DNA modifications at the DR 3' end on LbCas12a's functionality.
View Article and Find Full Text PDFJCO Precis Oncol
January 2025
Karmanos Cancer Institute and Department of Oncology, Wayne State University School of Medicine, Detroit, MI.
Cells
January 2025
Department of Molecular Medicine and Medical Biotechnologies, University of Naples 'Federico II', 80131 Naples, Italy.
Genomic integrity is critical for cellular homeostasis, preventing the accumulation of mutations that can drive diseases such as cancer. Among the mechanisms safeguarding genomic stability, the Base Excision Repair (BER) pathway plays a pivotal role in counteracting oxidative DNA damage caused by reactive oxygen species. Central to this pathway are enzymes like 8-oxoguanine glycosylase 1 (OGG1), which recognize and excise 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) lesions, thereby initiating a series of repair processes that restore DNA integrity.
View Article and Find Full Text PDFSci Rep
January 2025
Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Olomouc, Czech Republic.
Mismatched nucleobase uracil is commonly repaired through the base excision repair initiated by DNA uracil glycosylases. The data presented in this study strongly indicate that the nuclear uracil-N-glycosylase activity and nuclear protein content in human cell lines is highest in the S phase of the cell cycle and that its distribution kinetics partially reflect the DNA replication activity in replication foci. In this respect, the data demonstrate structural changes of the replication focus related to the uracil-N-glycosylase distribution several dozens of minutes before end of its replication.
View Article and Find Full Text PDFFree Radic Biol Med
January 2025
Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan. Electronic address:
8-Oxo-7,8-dihydroguanine (G, 8-hydroxyguanine), an oxidatively damaged base, induces mutations and is involved in cancer initiation. In addition to G:C→T:A transversions at the damaged site, it causes untargeted base substitution (action-at-a-distance) mutations at the G bases of 5'-GpA-3' sites in human cells. Paradoxically, OGG1, a DNA glycosylase involved in the base excision repair (BER) pathway, enhances the action-at-a-distance mutations by G.
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