Replication initiation and elongation fork rates within a differentially expressed human multicopy locus in early S phase
| Autor: | Rona S. Scott, Jean Michel H. Vos, K. Young Truong |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 1997 |
| Předmět: |
Transcriptionally active chromatin
Genetics DNA Replication Replication timing DNA replication Chromosome Mapping Eukaryotic DNA replication Replication Origin Biology Molecular biology DNA Ribosomal Chromatin S Phase Replication factor C Control of chromosome duplication Tumor Cells Cultured Origin recognition complex Humans S phase Research Article |
| DOI: | 10.17615/9feq-pb05 |
| Popis: | Replication of the 400 copies of the 43 kb human ribosomal RNA (rDNA) locus spans most of the S phase. To examine the basis for the unusual pattern of rDNA replication, a sensitive strategy was developed to map origins of DNA replication and measure apparent rates of fork progression within a chromosomal locus. This technique, termed differential intragenomic replication timing, revealed that initiation within the actively transcribed rDNA occurred in early S within a 10.7 kb region spanning the promoter and 5' external transcribed spacer. Forks emanating from this early bidirectional origin progressed at an apparent slow rate with the sense and anti-sense forks moving at 0.32 and 0.23 kb/min. Using a photochemical-based technique, the chromatin status of the rDNA repeats was assayed throughout the S phase. Approximately 85% of the rDNA repeats were in a transcriptionally active chromatin structure at the start of S phase. A progressive decrease in the transcription state of the rDNA loci was observed, reaching a minimum between 3 and 6 h in mid S phase. Altogether, the data suggest a link between RNA polymerase I mediated transcription and site-specific initiation of DNA replication within the rDNA multicopy locus. |
| Databáze: | OpenAIRE |
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