Project description:Schizosaccharomyces pombe Rad3 checkpoint kinase and its human ortholog ATR are essential for maintaining genome integrity in cells treated with genotoxins that damage DNA or arrest replication forks. Rad3 and ATR also function during unperturbed growth, although the events triggering their activation and their critical functions are largely unknown. Here, we use ChIP-on-chip analysis to map genomic loci decorated by phosphorylated histone H2A (gH2A), a Rad3 substrate that establishes a chromatin-based recruitment platform for DNA repair/checkpoint proteins. Our data showed that gH2A marks a diverse array of genomic features during S-phase, including natural replication fork barriers and a fork breakage site, retrotransposons, heterochromatin in the centromeres and telomeres, and ribosomal RNA (rDNA) repeats. The enrichment of gH2A at these sites was confirmed by multiple ChiP-qPCR experiments.
Project description:The metazoan nuclear periphery is involved in transcriptional regulation and chromatin organisation. To test whether this is also the case in the fission yeast Schizosaccharomyces pombe, we performed DamID experiments with two inner nuclear membrane (INM) proteins, Ima1 and Man1. The resulting map showed that about a third of the genome is associated with the nuclear periphery. We find that both INM proteins preferentially associate with lowly expressed genes, and are depleted from highly expressed genes. Further, intergenic regions of divergent gene pairs are more frequently associated with the periphery than convergent pairs, indicating that transcription points away from the periphery rather than toward it
