Maintaining replication origins in the face of genomic change.
Origins of replication present a paradox to evolutionary biologists. As a collection, they are absolutely essential genomic features, but individually are highly redundant and nonessential. It is therefore difficult to predict to what extent and in what regard origins are conserved over evolutionary time. Here, through a comparative genomic analysis of replication origins and chromosomal replication patterns in the budding yeasts Saccharomyces cerevisiae and Lachancea waltii, we assess to what extent replication origins survived genomic change produced from 150 million years of evolution. We find that L. waltii origins exhibit a core consensus sequence and nucleosome occupancy pattern highly similar to those of S. cerevisiae origins. We further observe that the overall progression of chromosomal replication is similar between L. waltii and S. cerevisiae. Nevertheless, few origins show evidence of being conserved in location between the two species. Among the conserved origins are those surrounding centromeres and adjacent to histone genes, suggesting that proximity to an origin may be important for their regulation. We conclude that, over evolutionary time, origins maintain sequence, structure, and regulation, but are continually being created and destroyed, with the result that their locations are generally not conserved.
Department of Genome Sciences, University of Washington, Seattle, Washington 98195, USA.
Sara C
SC
Di Rienzi
Kimberly C
KC
Lindstrom
Tobias
T
Mann
William S
WS
Noble
M K
MK
Raghuraman
Bonita J
BJ
Brewer
D001482:Base Composition; D002503:Centromere / Q000235:genetics; D015825:Chromosomes, Fungal; D016384:Consensus Sequence; D004261:DNA Replication; D005784:Gene Amplification; D015321:Gene Rearrangement; D016681:Genome, Fungal; D009154:Mutation; D009707:Nucleosomes / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D018741:Replication Origin; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D016615:Telomere / Q000235:genetics; D014158:Transcription, Genetic
D009707:Nucleosomes