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Biomedical subjects

Shin-ichiro Hiraga

Publications and source records attributed to Shin-ichiro Hiraga.

2 recordsLinked to original sources

OriDB: a DNA replication origin database.

Replication of eukaryotic chromosomes initiates at multiple sites called replication origins. Replication origins are best understood in the budding yeast Saccharomyces cerevisiae, where several complementary studies have mapped their locations genome-wide. We have collated these datasets, taking account of the resolution of each study, to generate a single list of distinct origin sites. OriDB provides a web-based catalogue of these confirmed and predicted S.cerevisiae DNA replication origin sites. Each proposed or confirmed origin site appears as a record in OriDB, with each record comprising seven pages. These pages provide, in text and graphical formats, the following information: genomic location and chromosome context of the origin site; time of origin replication; DNA sequence of proposed or experimentally confirmed origin elements; free energy required to open the DNA duplex (stress-induced DNA duplex destabilization or SIDD); and phylogenetic conservation of sequence elements. In addition, OriDB encourages community submission of additional information for each origin site through a User Notes facility. Origin sites are linked to several external resources, including the Saccharomyces Genome Database (SGD) and relevant publications at PubMed. Finally, a Chromosome Viewer utility allows users to interactively generate graphical representations of DNA replication data genome-wide. OriDB is available at www.oridb.org.

Chromosomes, Fungal↗

The Ctf18 RFC-like complex positions yeast telomeres but does not specify their replication time.

Chromosome ends in Saccharomyces cerevisiae are positioned in clusters at the nuclear rim. We report that Ctf18, Ctf8, and Dcc1, the subunits of a Replication Factor C (RFC)-like complex, are essential for the perinuclear positioning of telomeres. In both yeast and mammalian cells, peripheral nuclear positioning of chromatin during G1 phase correlates with late DNA replication. We find that the mislocalized telomeres of ctf18 cells still replicate late, showing that late DNA replication does not require peripheral positioning during G1. The Ku and Sir complexes have been shown to act through separate pathways to position telomeres, but in the absence of Ctf18 neither pathway can act fully to maintain telomere position. Surprisingly CTF18 is not required for Ku or Sir4-mediated peripheral tethering of a nontelomeric chromosome locus. Our results suggest that the Ctf18 RFC-like complex modifies telomeric chromatin to make it competent for normal localization to the nuclear periphery.

Cell Nucleus↗