Plech Marcin, Tomala Katarzyna, Tutaj Hanna, Piwcewicz Dominika Ewa, de Visser J Arjan G M, Korona Ryszard
Institute of Environmental Sciences, Jagiellonian University, Krakow, Poland.
Laboratory of Genetics, Wageningen University, HB Wageningen, Netherlands.
PLoS Genet. 2017 May 11;13(5):e1006768. doi: 10.1371/journal.pgen.1006768. eCollection 2017 May.
The functional basis of genetic robustness, the ability of organisms to suppress the effects of mutations, remains incompletely understood. We exposed a set of 15 strains of Saccharomyces cerevisiae form diverse environments to increasing doses of the chemical mutagen EMS. The number of the resulting random mutations was similar for all tested strains. However, there were differences in immediate mortality after the mutagenic treatment and in defective growth of survivors. An analysis of gene expression revealed that immediate mortality was lowest in strains with lowest expression of transmembrane proteins, which are rich in thiol groups and thus vulnerable to EMS. A signal of genuine genetic robustness was detected for the other trait, the ability to grow well despite bearing non-lethal mutations. Increased tolerance of such mutations correlated with high expression of genes responsible for the oxidative energy metabolism, suggesting that the negative effect of mutations can be buffered if enough energy is available. We confirmed this finding in three additional tests of the ability to grow on (i) fermentable or non-fermentable sources of carbon, (ii) under chemical inhibition of the electron transport chain and (iii) during overexpression of its key component, cytochrome c. Our results add the capacity to generate energy as a general mechanism of genetic robustness.
遗传稳健性的功能基础，即生物体抑制突变影响的能力，目前仍未被完全理解。我们将一组来自不同环境的15株酿酒酵母暴露于剂量不断增加的化学诱变剂甲基磺酸乙酯（EMS）中。所有测试菌株产生的随机突变数量相似。然而，诱变处理后的即时死亡率以及存活菌株的生长缺陷存在差异。基因表达分析表明，跨膜蛋白表达最低的菌株即时死亡率最低，这些跨膜蛋白富含硫醇基团，因此易受EMS影响。对于另一个性状，即尽管携带非致死突变仍能良好生长的能力，检测到了真正的遗传稳健性信号。对这类突变的耐受性增加与负责氧化能量代谢的基因的高表达相关，这表明如果有足够的能量，突变的负面影响可以得到缓冲。我们在另外三项关于生长能力的测试中证实了这一发现，这三项测试分别是：（i）在可发酵或不可发酵的碳源上生长；（ii）在电子传递链受到化学抑制的情况下生长；（iii）在其关键成分细胞色素c过表达期间生长。我们的研究结果将产生能量的能力作为遗传稳健性的一种普遍机制补充了进来。
