Sequence analysis of three fragments of maize nuclear DNA which replicate autonomously in yeast.

There maize nuclear DNA fragments were isolated on the basis of their ability to confer replication on chimeric plasmids in yeast. These Eco RI fragments of 2.5, 2.8 and 5.5 kb are repeated elements within the maize genome. The 2.5 and 2.8 kb fragments represent a family of elements repeated 11 000 times in the maize haploid genome, while the 5.5 kb fragment is part of another family of 28 000 elements. These fragments were subcloned to further define the unique region of ARS activity. The sequence of each 550-650 bp ARS subclone is reported here, and compared to the flanking regions which do not show ARS activity. The ARS elements are 65-70% A+T as compared to 50-55% for the maize genome as a whole. There is approximately 15% sequence divergence, as well as variation of ARS efficiency, among family members. ARS subclones contain the proposed yeast consensus sequence.