title: FOB1 affects DNA topoisomerase I in vivo cleavages in the enhancer region of the Saccharomyces cerevisiae ribosomal DNA locus.
abstract: In Saccharomyces cerevisiae the FOB1 gene affects replication fork blocking activity at the replication fork block (RFB) sequences and promotes recombination events within the rDNA cluster. Using in vivo footprinting assays we mapped two in vivo Fob1p-binding sites, RFB1 and RFB3, located in the rDNA enhancer region and coincident with those previously reported to be in vitro binding sites. We previously provided evidences that DNA topoisomerase I is able to cleave two sites within this region. The results reported in this paper, indicate that the DNA topoisomerase I cleavage specific activity at the enhancer region is affected by the presence of Fob1p and independent of replication and transcription activities. We thus hypothesize that the binding to DNA of Fob1p itself may be the cause of the DNA topoisomerase I activity in the rDNA enhancer.
authors.affiliation: Dipartimento di Genetica e Biologia Molecolare, Università di Roma La Sapienza, Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Di Felice
authors.forename: Francesco
authors.initials: F
authors.lastname: Cioci
authors.forename: Giorgio
authors.initials: G
authors.lastname: Camilloni
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D002843:Chromatin / Q000737:chemistry; D004261:DNA Replication; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004275:DNA, Ribosomal / Q000737:chemistry / Q000378:metabolism; D021903:DNA, Ribosomal Spacer / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D017353:Gene Deletion; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer; D004268:DNA-Binding Proteins; C105579:FOB1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D004264:DNA Topoisomerases, Type I