The origin recognition complex (ORC) specifies replication origin location. The 
Saccharomyces cerevisiae ORC recognizes the ARS (autonomously replicating 
sequence) consensus sequence (ACS), but only a subset of potential genomic sites 
are bound, suggesting other chromosomal features influence ORC binding. Using 
high-throughput sequencing to map ORC binding and nucleosome positioning, we 
show that yeast origins are characterized by an asymmetric pattern of positioned 
nucleosomes flanking the ACS. The origin sequences are sufficient to maintain a 
nucleosome-free origin; however, ORC is required for the precise positioning of 
nucleosomes flanking the origin. These findings identify local nucleosomes as an 
important determinant for origin selection and function.