Plasmid instability in methylotrophic yeast Hansenula polymorpha: The capture of chromosomal DNA fragments by integrative plasmids

In Hansenula polymorpha, integrative plasmids became replicative as a resul t of capturing chromosomal fragments that contain HARS providing for plasmi d autonomous replication. When H. polymorpha was transformed with linearize d plasmids, a fragment was inserted in their cleavage site. The yield of tr ansformants carrying rearranged plasmids was the same whether a vector had sticky or blunt ends and whether its terminal sequences had genomic homolog s or not. The capture of genomic fragments was often associated with deleti ons from plasmid regions flanking the cleavage site. Since only one of them was altered in most cases, recombination was assumed to be initiated by on e end of the plasmid, the other being for a some time free and accessible t o degradation.