Killer Plasmids

Linear plasmid encoded toxins were detected in K. lactis, Pichia inosi-tovora, P. acaciae, and Debaryomyces robertsiae (synonym Wingea robertsiae) (Gunge et al. 1981; Worsham and Bolen 1990; Hayman and Bolen 1991; Klassen and Meinhardt 2002; see Table 2). Genetic and biochemical analyses provided evidence for large (>100 kDa) heteromeric proteins which are encoded by two separate genes (Table 2). The most thoroughly studied toxin is the K. lactis zymocin. A detailed picture is available with respect to biogenesis and multistep action on sensitive target cells. Though there is evidence for similar mechanisms being instrumental in target cell entrance, clearly different intracellular toxin targets must be conceded in other instances, eventually leading to classification of two functional subtypes (I and II).

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