Transcription-dependent recombination and the role of fork collision in yeast rDNA
It is speculated that the function of the replication fork barrier (RFB) site is to avoid collision between the 35S rDNA transcription machinery and the DNA replication fork, because the RFB site is located near the 3'-end of the gene and inhibits progression of the replication fork moving in t...
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Published in | Genes & development Vol. 17; no. 12; pp. 1497 - 1506 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
Cold Spring Harbor Laboratory Press
15.06.2003
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Subjects | |
Online Access | Get full text |
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Summary: | It is speculated that the function of the replication fork barrier (RFB) site is to avoid collision between the 35S rDNA transcription machinery and the DNA replication fork, because the RFB site is located near the 3'-end of the gene and inhibits progression of the replication fork moving in the opposite direction to the transcription machinery. However, the collision has never been observed in a blockless (fob1) mutant with 150 copies of rDNA. The gene FOB1 was shown previously to be required for replication fork blocking activity at the RFB site, and also for the rDNA copy number variation through unequal sister-chromatid recombination. This study documents the detection of fork collision in an fob1 derivative with reduced rDNA copy number (approximately 20) using two-dimensional agarose gel electrophoresis. This suggests that most of these reduced copies are actively transcribed. The collision was dependent on the transcription by RNA polymerase I. In addition, the transcription stimulated rDNA copy number variation, and the production of the extrachromosomal rDNA circles (ERCs), whose accumulation is thought to be a cause of aging. These results suggest that such a transcription-dependent fork collision induces recombination, and may function as a general recombination trigger for multiplication of highly transcribed single-copy genes. |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 Article published online ahead of print. Article and publication date are at http://www.genesdev.org/cgi/doi/10.1101/gad.1085403. E-MAIL koba@nibb.ac.jp ; FAX 81-564-55-7695. Corresponding author. |
ISSN: | 0890-9369 1549-5477 |
DOI: | 10.1101/gad.1085403 |