Institute of Environmental Sciences, Jagiellonian University, Krakow, Poland; Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands.
FEMS Yeast Res. 2013 Dec;13(8):856-9. doi: 10.1111/1567-1364.12086. Epub 2013 Oct 7.
Viruses are found in almost all organisms and physical habitats. One interesting example is the yeast viral 'killer system'. The virus provides the host with a toxin directed against strains that do not carry it, while the yeast cell enables its propagation. Although yeast viruses are believed to be common, they have been actually described only for a limited number of yeast isolates. We surveyed 136 Saccharomyces cerevisiae and S. paradoxus strains of known origin and phylogenetic relatedness. Of these, 14 (c. 10%) were infected by killer viruses of one of the three types: K1, K2 or K28. As many as 34 strains (c. 25%) were not sensitive to at least one type of the killer toxin. In most cases, resistance did not disappear after attempts to cure the host strains from their viruses, suggesting that it was encoded in the host's genome. In terms of phylogeny, killer strains appear to be more related to each other than to nonkiller ones. No such tendency is observed for the phenotype of toxin resistance. Our results suggest that even if the killer toxins are not always present, they do play significant role in yeast ecology and evolution.
病毒几乎存在于所有生物体和物理栖息地中。一个有趣的例子是酵母病毒“杀伤系统”。这种病毒为宿主提供了一种针对不携带它的菌株的毒素，而酵母细胞则使其得以繁殖。尽管人们认为酵母病毒很常见，但实际上只对有限数量的酵母分离株进行了描述。我们调查了 136 株已知起源和系统发育相关的酿酒酵母和 S. paradoxus 菌株。其中，14 株（约 10%）被三种类型之一的杀伤病毒感染：K1、K2 或 K28。多达 34 株（约 25%）对至少一种杀伤毒素不敏感。在大多数情况下，即使尝试从宿主菌株中清除病毒，抗性也不会消失，这表明它是由宿主基因组编码的。从系统发育的角度来看，杀伤株似乎比非杀伤株彼此之间更相关。对于毒素抗性的表型，没有观察到这种趋势。我们的结果表明，即使杀伤毒素并不总是存在，它们在酵母的生态和进化中确实发挥了重要作用。
