Reversible Top1 cleavage complexes are stabilized strand-specifically at the ribosomal replication fork barrier and contribute to ribosomal DNA stability.

ABSTRACT: Various topological constraints at the ribosomal DNA (rDNA) locus impose an extra challenge for transcription and DNA replication, generating constant torsional DNA stress. The topoisomerase Top1 is known to release such torsion by single-strand nicking and re-ligation in a process involving transient covalent Top1 cleavage complexes (Top1cc) with the nicked DNA. Here we show that Top1ccs, despite their usually transient nature, are specifically targeted to and stabilized at the ribosomal replication fork barrier (rRFB) of budding yeast, establishing a link with previously reported Top1 controlled nicks. Using ectopically engineered rRFBs, we establish that the rRFB sequence itself is sufficient for induction of DNA strand-specific and replication-independent Top1ccs. These Top1ccs accumul

SUBMITTER: Krawczyk C 

PROVIDER: S-EPMC4005688 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature