Initiation at Closely Spaced Replication Origins in a Yeast Chromosome

Abstract
Replication of eukaryotic chromosomes involves initiation atorigins spaced an average of 50 to 100 kilobase pairs. In yeast,potential origins can be recognized as autonomous replicationsequences (ARSs) that allow maintenance of plasmids. However, thereare more ARS elements than active chromosomal origins. The possibilitywas examined that close spacing of ARSs can lead to inactiveorigins. Two ARSs located 6.5 kilobase pairs apart can indeedinterfere with each other. Replication is initiated from one or theother ARS with equal probability, but rarely (< 5%) from both ARSs onthe same DNA molecule.