Delta sequences and double symmetry in a yeast chromosomal replicator region

A specific autonomously replicating sequence (ars2) occurring near the ARG4 locus on chromosome VIII of yeast (Saccharomyces cerevisiae) has been localized on a 100 base-pair region of DNA. The nucleotide sequence of a 1517 bp² fragment spanning the ars2 region has been determined. The 100 bp ars2 region contains an 18 bp A + T sequence of perfect double symmetry (alphabetic symmetry superimposed on dyad symmetry). A 0.3 kb repetitive sequence (solo delta sequence) and a tRNA^Gln gene are located within the 1517 bp fragment along with ars2. The 100 bp ars2 region may be located within a divergent delta sequence that is oriented in an inverted and nearly tandem position with respect to the solo delta sequence.