Stress responses of linear plasmids from Debaryomyces hansenii.

The triplet linear plasmids pDHL1/2/3 from the salt-tolerant yeast Debaryomyces hansenii TK are localized in the cytoplasm and characterized by a unique feature that they require environmental stressors (0.3 M NaCl or solutes such as sorbitol with equivalent osmolarity) for stable replication and maintenance. The degree of osmolarity dependence of pDHLs was greatly affected by growth temperature of the host cells: the stability of pDHLs was maintained in the absence of osmolarity in cells growing at 25 degrees C, and required osmorarity equivalent to 0.