Kluyveromyces lactiskiller system:ORF1of pGKL2 has no function in immunity expression and is dispensable for killer plasmid replication and maintenance
✍ Scribed by R. Schaffrath; M. J. R. Stark; N. Gunge; F. Meinhardt
- Publisher
- Springer-Verlag
- Year
- 1992
- Tongue
- English
- Weight
- 929 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0172-8083
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✦ Synopsis
To functionally characterize the genes encoded by the larger killer plasmid pGKL2 from Kluyveromyces lactis a previously developed in-vivo recombination system was exploited. An in-vitro modified version of the cytoplasmically expressible LEU2 gene cartridge (LEU2*) flanked by appropriate pGKL2 segments was used to replace the central part of the ORF1 region of pGKL2. Transformation of a Leu- killer strain resulted in the expected disruption of ORF1 in the resident pGKL2. The Leu+ transformants obtained can be assigned to three classes. Class I carries both killer plasmids, pGKL1/2, and the recombinant pGKL2 derivative termed pRKL2. Class II and III additionally harbor palindrome and hairpin-like plasmids, respectively. Upon subculturing of class I transformants under selective pressure, segregation of the native pGKL2 and the recombinant pRKL2 eventually occurs resulting in total loss of pGKL2. No differences concerning killer and immunity phenotype between a pRKL2-harboring strain and the native pGKL2-carrying recipient could be detected. Thus pGKL2 ORF1 is dispensable for both expression of killer/immunity phenotypes and for the replication and maintenance of the K. lactis killer plasmids.