MODULAR SEQUENCE ELEMENTS ASSOCIATED WITH ORIGIN REGIONS IN EUKARYOTIC CHROMOSOMAL DNA

We have postulated that chromosomal replication origin regions in euka ryotes have in common clusters of certain modular sequence elements (B enbow, Zhao, and Larson, BioEssays 14, 661-670, 1992). In this study, computer analyses of DNA sequences from six origin regions showed that each contained one or more potential initiation regions consisting of a putative DUE (DNA unwinding element) aligned with clusters of SAR ( scaffold associated region), and ARS (autonomously replicating sequenc e) consensus sequences, and pyrimidine tracts. The replication origins analyzed were from the following loci: Tetrahymena thermophila macron uclear rDNA gene, Chinese hamster ovary dihydrofolate reductase amplic on, human c-myc protooncogene, chicken histone H5 gene, Drosophila mel anogaster chorion gene cluster on the third chromosome, and Chinese ha mster ovary rhodopsin gene. The locations of putative initiation regio ns identified by the computer analyses were compared with published da ta obtained using diverse methods to map initiation sites. For at leas t four loci, the potential initiation regions identified by sequence a nalysis aligned with previously mapped initiation events. A consensus DNA sequence, WAWTTDDWW-WDHWGWHMAWTT, was found within the potential i nitiation regions in every case. An additional 35 kb of combined flank ing sequences from the six loci were also analyzed, but no additional copies of this consensus sequence were found.