Transcription Termination Factor reb1p Causes Two Replication Fork Barriers at Its Cognate Sites in Fission Yeast Ribosomal DNA In Vivo

Autor: Pablo E. Hernández, Jorge Bernardo Schvartzman, Dora B. Krimer, Alicia Sánchez-Gorostiaga, Carlos López-Estraño
Rok vydání: 2004
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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ISSN: 1098-5549
DOI: 10.1128/mcb.24.1.398-406.2004
Popis: 31 p.-5 fig.
Polar replication fork barriers (RFBs) near the 3'-end of the rRNA transcriptional unit are a conserved feature of rDNA replication in eukaryotes. In the mouse, in vivo studies indicate that the cis-acting Sal boxes required for rRNA transcription termination are also involved in replication fork blockage. On the contrary, in the budding yeast Saccharomyces cerevisiae, the rRNA transcription termination factors are not required for RFBs. Here we characterized the rDNA RFBs in the fission yeast Schizosaccharomyces pombe. S. pombe rDNA contains three closely spaced polar replication barriers named RFB1-3, in the 3’ to 5’ order. The transcription termination protein reb1 and its two binding sites, present at the 3’ end of the coding region, were required for fork arrest at RFB2 and RFB3 in vivo. On the other hand, fork arrest at the strongest RFB1 barrier was independent of the above transcription termination factors. Therefore, RFB2 and RFB3 resemble the barriers present in the mouse rDNA, whereas RFB1 is similar to the budding yeast RFBs. These results suggest that during evolution, cis- and trans-acting factors required for rRNA transcription termination became also involved in replication fork blockage. S. pombe would be a transitional species where both mechanisms coexist.
This work was partially supported by Spanish grants 99/0850 from the Fondo de Investigación Sanitaria (Ministerio de Sanidad y Consumo), SAF2001-1740 from the Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica (Ministerio de Ciencia y Tecnología), PB98-048 from the Comisión Interministerial de Ciencia y Tecnología (CICYT) and a fellowship from the Consejería de Educación de la Comunidad de Madrid-Fondo Social Europeo to A.S.-G.
Databáze: OpenAIRE