Behaviour of plasmid containing C4A2 repeats in S. cerevisiae and S. pombe.

Plasmid, which combined the complete genome of BPV-I, yeast ARS, LEU yeast selectable marker gene, the NEO selectable marker gene and inverted (C4A2)n telomeric repeat gene sequences cloned originally from Tetrahymena thermophila, was constructed. It was introduced in either circular or linear form to Saccharomyces cerevisiae or Schizosaccharomyces pombe. Although both yeasts could replicate the plasmid extrachromosomally, irrespective of whether it was introduced as a circular or linear structure, the yeasts did differ in their ability to resolve a circular plasmid carrying the telomeric sequences into linear forms. S. cerevisiae was found to resolve the circular form of pCA/LEU/ARS to the linear structure, whereas circular pCA/LEU/ARS remained circular in S. pombe. On the other hand, pCA/LEU/ARS which had been previously linearised at the telomeric sequence was maintained as a linear structure in S. pombe and S. cerevisiae.