The perinuclear localization of Saccharomyces cerevisiae telomeres provides a useful model for studying mechanisms that control chromosome positioning. Telomeres tend to be localized at the nuclear periphery during early interphase, but following S phase they delocalize and remain randomly positioned within the nucleus. We investigated whether DNA replication causes telomere delocalization from the nuclear periphery. Using live-cell fluorescence microscopy, we show that delaying DNA replication causes a corresponding delay in the dislodgment of telomeres from the nuclear envelope, demonstrating that replication of individual telomeres causes their delocalization. Telomere delocalization is not simply the result of recruitment to a replication factory in the nuclear interior, since we found that telomeric DNA replication can occur either at the nuclear periphery or in the nuclear interior. The telomere-binding complex Ku is one of the factors that localizes telomeres to the nuclear envelope. Using a gene locus tethering assay, we show that Ku-mediated peripheral positioning is switched off after DNA replication. Based on these findings, we propose that DNA replication causes telomere delocalization by triggering stable repression of the Ku-mediated anchoring pathway. In addition to maintaining genetic information, DNA replication may therefore regulate subnuclear organization of chromatin.
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http://dx.doi.org/10.1101/gad.486208 | DOI Listing |
J Vis Exp
January 2025
Institute of Biochemistry and Molecular Biology, Hengyang Medical School, University of South China; National Health Commission Key Laboratory of Birth Defect Research and Preventio, Hunan Provincial Maternal and Child Health Care Hospital;
Both DNA replication and RNA transcription utilize genomic DNA as their template, necessitating spatial and temporal separation of these processes. Conflicts between the replication and transcription machinery, termed transcription-replication conflicts (TRCs), pose a considerable risk to genome stability, a critical factor in cancer development. While several factors regulating these collisions have been identified, pinpointing primary causes remains difficult due to limited tools for direct visualization and clear interpretation.
View Article and Find Full Text PDFmBio
January 2025
Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
Unlabelled: Peptidoglycan (PG) is an important bacterial macromolecule that confers cell shape and structural integrity, and is a key antibiotic target. Its synthesis and turnover are carefully coordinated with other cellular processes and pathways. Despite established connections between the biosynthesis of PG and the outer membrane, or PG and DNA replication, links between PG and folate metabolism remain comparatively unexplored.
View Article and Find Full Text PDFNucleic Acids Res
January 2025
College of Life Sciences, Beijing Normal University, Beijing 100875, China.
Mammalian J-domain protein DNAJC9 interacts with histones H3-H4 and is important for cell proliferation. However, its exact function remains unclear. Here, we show that, in the fission yeast Schizosaccharomyces pombe, loss of Djc9, the ortholog of DNAJC9, renders the histone chaperone Asf1 no longer essential for growth.
View Article and Find Full Text PDFNucleic Acids Res
January 2025
Department of Pharmaceutical Sciences, University of California, Irvine, CA 92697-3958, United States.
Growth in the development of engineered polymerases for synthetic biology has led to renewed interest in assays that can measure the fidelity of polymerases that are capable of synthesizing artificial genetic polymers (XNAs). Conventional approaches require purifying the XNA intermediate of a replication cycle (DNA → XNA → DNA) by denaturing polyacrylamide gel electrophoresis, which is a slow, costly, and inefficient process that requires a large-scale transcription reaction and careful extraction of the XNA strand from the gel slice. In an effort to streamline the assay, we developed a purification-free approach in which the XNA transcription and reverse transcription steps occur inside the matrix of a hydrogel-coated magnetic particle.
View Article and Find Full Text PDFBiochem J
January 2025
The Sun Yat-Sen University, Guangzhou, China.
The N6-methyladenine (6mA) modification is an essential epigenetic marker and plays a crucial role in processes, such as DNA repair, replication, gene expression regulation, etc. YerA from Bacillus subtilis is considered a novel class of enzymes capable of catalyzing the deamination of 6mA to produce hypoxanthine. Despite the significance of this type of enzymes in bacterial self-defense systems and potential applications as a gene-editing tool, the substrate specificity, the catalytic mechanism and the physiological function of YerA are currently unclear due to the lack of structural information.
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