101. Replication focus-forming activity 1 and the Werner syndrome gene product
- Author
-
Hong Yan, John Newport, Ryuji Kobayashi, and Chin-Yi Chen
- Subjects
DNA Replication ,Werner Syndrome Helicase ,Molecular Sequence Data ,Eukaryotic DNA replication ,Biology ,Pre-replication complex ,DNA replication factor CDT1 ,Xenopus laevis ,Adenosine Triphosphate ,Control of chromosome duplication ,Minichromosome maintenance ,Replication Protein A ,Genetics ,Animals ,Humans ,Amino Acid Sequence ,Cloning, Molecular ,Replication protein A ,RecQ Helicases ,Sequence Homology, Amino Acid ,DNA Helicases ,DNA ,Molecular biology ,Cell biology ,DNA-Binding Proteins ,Exodeoxyribonucleases ,Licensing factor ,biology.protein ,Origin recognition complex ,Werner Syndrome - Abstract
The initiation of DNA replication involves a minimum of four factors: a specific DNA sequence (origin), an initiator protein which binds to the origin, a helicase that unwinds the origin and a protein that binds single-stranded DNA that stabilizes the unwound origin. In eukaryotic cells, the origin recognition complex (ORC) is the initiator protein and replication protein A (RPA; ref. 3) is the single-stranded DNA-binding protein. However, the helicase has not been identified and the nature of origins remains elusive, except in the case of Saccharomyces cerevisiae. A unique feature of eukaryotic DNA replication is that it occurs at a few-hundred discrete foci. It has thus been proposed that a real origin must contain a specific DNA sequence and must be attached to replication foci. Using Xenopus laevis egg extracts, we have identified and purified a 170-kD protein, focus-forming activity 1 (FFA-1), which is required for the formation of replication foci. Here we report that FFA-1 has DNA-helicase activity. Moreover, it is a homologue of the human Werner syndrome gene product WRN, a protein associated with premature ageing in humans.
- Published
- 1998