YEAST LINEAR PLASMIDS WITH T(2)AG(3) TELOMERES - TEL-STABILITY(CEN ANTAGONISM AND GENETIC AND MOLECULAR)

A linear plasmid containing ARS1, CEN4, and 48 bp of vertebrate (T(2)A G(3)) telomeric sequences at each end was used to transform Saccharomy ces cerevisiae. Only circular plasmids that had lost the centromere an d had retained the T(2)AG(3) sequences were obtained, indicating that the vertebrate T(2)AG(3) sequences and the yeast CEN4 could not be sim ultaneously present in this vector. This hypothesis was verified by re moving the CEN4 sequence from the construct. In fact, the resulting tr ansformants contained two classes of efficiently replicating linear pl asmids: one of the expected size and one about twice as large. During subsequent growth, plasmids of the former, but not latter, class were subjected to concatemer formation. This can best be explained by recom bination events involving the T(2)AG(3) sequences al the ends of the m olecule, since very similar centric and acentric linear plasmids beari ng Tetrahymena telomeric ends replicated faithfully.