Non-proteinogenic amino acids, such as the proline analog L-azetidine-2-carboxylic acid (AZC), are detrimental to cells because they are mis-incorporated into proteins and lead to proteotoxic stress. Our goal was to identify genes that show chemical-genetic interactions with AZC in Saccharomyces cerevisiae and thus also potentially define the pathways cells use to cope with amino acid mis-incorporation. Screening the yeast deletion and temperature sensitive collections, we found 72 alleles with negative chemical-genetic interactions with AZC treatment and 12 alleles that suppress AZC toxicity. Many of the genes with negative chemical-genetic interactions are involved in protein quality control pathways through the proteasome. Genes involved in actin cytoskeleton organization and endocytosis also had negative chemical-genetic interactions with AZC. Related to this, the number of actin patches per cell increases upon AZC treatment. Many of the same cellular processes were identified to have interactions with proteotoxic stress caused by two other amino acid analogs, canavanine and thialysine, or a mistranslating tRNA variant that mis-incorporates serine at proline codons. Alleles that suppressed AZC-induced toxicity functioned through the amino acid sensing TOR pathway or controlled amino acid permeases required for AZC uptake. Further suggesting the potential of genetic changes to influence the cellular response to proteotoxic stress, overexpressing many of the genes that had a negative chemical-genetic interaction with AZC suppressed AZC toxicity.

非蛋白质氨基酸，例如脯氨酸类似物L-氮杂环丁烷-2-羧酸（AZC），对细胞有害，因为它们被错误地掺入蛋白质并导致蛋白毒性应激。我们的目标是鉴定在酿酒酵母中与AZC发生化学-遗传相互作用的基因。因此也潜在地定义了细胞用于应对氨基酸错误掺入的途径。筛选酵母缺失和温度敏感的集合，我们发现72个等位基因与AZC处理具有负的化学-遗传相互作用，以及12个抑制AZC毒性的等位基因。化学-遗传相互作用为负的许多基因都通过蛋白酶体参与蛋白质质量控​​制途径。肌动蛋白细胞骨架组织和内吞作用涉及的基因也与AZC具有负的化学遗传相互作用。与此相关的是，AZC处理后，每个细胞的肌动蛋白补丁数量增加。已确定许多相同的细胞过程与由另外两种氨基酸类似物卡那万胺和硫赖氨酸引起的蛋白毒性应激有相互作用，或在脯氨酸密码子上错误掺入丝氨酸的错误翻译tRNA变体。抑制AZC诱导毒性的等位基因通过氨基酸感应TOR途径或AZC摄取所需的受控氨基酸通透酶起作用。进一步表明遗传改变可能影响细胞对蛋白毒性胁迫的反应，过表达许多与AZC负化学-遗传相互作用的基因抑制了AZC毒性。