Characterization of DNA replicators of a 75-kb region of Chromosome 2 of fission yeast, Schizosacharomyces pombe

DNA replication origins of a 75-kb region of chromosome 2 of Schizosacharomyces pombe, are well characterized. Here, we have further characterized two origins, ars2-3358 and ars2-3363 on plasmids using an Autonomous Replicating Sequences (ARS) assay. Sequence analysis of the five ARSs located within the 75-kb region revealed several asymmetric AT motifs [≥]10 bp in each of these origins. Interestingly, we have also found a 29 bp AT-rich sequence (29W) in ars2-3358, which alone is not sufficient to provide DNA replication origins to plasmid. A genomic search for asymmetric AT motifs [≥]10 bp gave a total 2309 near matches to 9 of these motifs in the genome. Majority (>65% to >77%) of six of these AT motifs overlapped with the earlier mapped genome-wide DNA replication origins. Moreover, functional comparison of these AT motifs to the deletion and mutational studies showed strong correlation with DNA replication origins efficiency. Therefore, we hypothesize that these sequences are important redundant core elements of S. pombe origins.