Plasmid functions involved in the stable propagation of the pKD1 circular plasmid inKluyveromyces lactis
✍ Scribed by Michele M. Bianchi; Roberta Santarelli; Laura Frontali
- Publisher
- Springer-Verlag
- Year
- 1991
- Tongue
- English
- Weight
- 881 KB
- Volume
- 19
- Category
- Article
- ISSN
- 0172-8083
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✦ Synopsis
Plasmid factors involved in the stable propagation of pKD1-derived vectors in Kluyveromyces lactis transformants have been identified. Three genes (A, B and C) have been found to be present in pKD1: the interruption of the B and C genes led to high plasmid instability. Stability could be restored in trans when host cells contained pKD1 as the resident plasmid (pKD1+ strains). The A gene, which codes for a site-specific recombinase, did not affect plasmid partitioning. Vectors bearing only the pKD1 replication origin (or a chromosomal ARS), and no other pKD1 sequence, were very unstable both in the presence and absence of the resident plasmid in host cells. These vectors could be stabilized in pKD1+ strains, but not in pKD1 degree strains, by the insertion of a 200 bp-long pKD1 sequence. This sequence, called the cis-acting stability locus (CSL), together with the products of the B and C genes, ensured plasmid partitioning at cell division. Possible hairpin structures and direct repeats were regularly spaced within the CSL. This region, and the corresponding cis-acting stabilizing elements of other yeast plasmids, did not have sequence homology but shared some structural regularities.