Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
Department of Plant Pathology and Microbiology, Institute of Environmental Science, Robert H. Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel.
Yeast. 2024 Sep;41(9):549-559. doi: 10.1002/yea.3975. Epub 2024 Jul 30.
The toxicity of non-proteinogenic amino acids has been known for decades. Numerous reports describe their antimicrobial/anticancer potential. However, these molecules are often toxic to the host as well; thus, a synthetic lethality approach that reduces the dose of these toxins while maintaining toxicity can be beneficial. Here we investigate synthetic lethality between toxic amino acids, the retrograde pathway, and molecular chaperones. In Saccharomyces cerevisiae, mitochondrial retrograde (RTG) pathway activation induces transcription of RTG-target genes to replenish alpha-ketoglutarate and its downstream product glutamate; both metabolites are required for arginine and lysine biosynthesis. We previously reported that tolerance of canavanine, a toxic arginine derivative, requires an intact RTG pathway, and low-dose canavanine exposure reduces the expression of RTG-target genes. Here we show that only a few of the examined chaperone mutants are sensitive to sublethal doses of canavanine. To predict synthetic lethality potential between RTG-target genes and chaperones, we measured the expression of RTG-target genes in canavanine-sensitive and canavanine-tolerant chaperone mutants. Most RTG-target genes were induced in all chaperone mutants starved for arginine; the same trend was not observed under lysine starvation. Canavanine exposure under arginine starvation attenuated and even reversed RTG-target-gene expression in the tested chaperone mutants. Importantly, under nearly all tested genetic and pharmacological conditions, the expression of IDH1 and/or IDH2 was induced. In agreement, idh1 and idh2 mutants are sensitive to canavanine and thialysine and show synthetic growth inhibition with chaperone mutants. Overall, we show that inhibiting molecular chaperones, RTG-target genes, or both can sensitize cells to low doses of toxic amino acids.
非蛋白氨基酸的毒性已经为人所知数十年了。大量的报道描述了它们的抗菌/抗癌潜力。然而，这些分子通常对宿主也有毒性；因此，一种减少这些毒素剂量而保持毒性的合成致死性方法可能是有益的。在这里，我们研究了有毒氨基酸、逆行途径和分子伴侣之间的合成致死性。在酿酒酵母中，线粒体逆行（RTG）途径的激活诱导 RTG 靶基因的转录，以补充α-酮戊二酸及其下游产物谷氨酸；这两种代谢物都是精氨酸和赖氨酸生物合成所必需的。我们之前报道过，毒性精氨酸衍生物-canavanine 的耐受性需要一个完整的 RTG 途径，而低剂量 canavanine 暴露会降低 RTG 靶基因的表达。在这里，我们表明，在检查的几种伴侣突变体中，只有少数对亚致死剂量的 canavanine 敏感。为了预测 RTG 靶基因和伴侣之间的合成致死性潜力，我们测量了 canavanine 敏感和 canavanine 耐受伴侣突变体中的 RTG 靶基因的表达。在所有缺乏精氨酸的伴侣突变体中，大多数 RTG 靶基因都被诱导；在赖氨酸饥饿的情况下，没有观察到相同的趋势。在精氨酸饥饿下暴露于 canavanine 会减弱甚至逆转测试伴侣突变体中的 RTG 靶基因表达。重要的是，在几乎所有测试的遗传和药理学条件下，IDH1 和/或 IDH2 的表达都被诱导。在协议中，idh1 和 idh2 突变体对 canavanine 和 thialysine 敏感，并与伴侣突变体表现出合成生长抑制。总的来说，我们表明，抑制分子伴侣、RTG 靶基因或两者都可以使细胞对低剂量的有毒氨基酸敏感。
