Genetic screens have been used extensively to probe interactions between nuclear genes and their impact on phenotypes. Probing interactions between mitochondrial genes and their phenotypic outcome, however, has not been possible due to a lack of tools to map the responsible polymorphisms. Here, using a toolkit we previously established in Drosophila, we isolate over 300 recombinant mitochondrial genomes and map a naturally occurring polymorphism at the cytochrome c oxidase III residue 109 (CoIII¹⁰⁹) that fully rescues the lethality and other defects associated with a point mutation in cytochrome c oxidase I (CoI^T300I). Through lipidomics profiling, biochemical assays and phenotypic analyses, we show that the CoIII¹⁰⁹ polymorphism modulates cardiolipin binding to prevent complex IV instability caused by the CoI^T300I mutation. This study demonstrates the feasibility of genetic interaction screens in animal mitochondrial DNA. It unwraps the complex intra-genomic interplays underlying disorders linked to mitochondrial DNA and how they influence disease expression.

遗传筛选已被广泛用于探测核基因之间的相互作用及其对表型的影响。然而，由于缺乏绘制相关多态性的工具，探究线粒体基因与其表型结果之间的相互作用一直是不可能的。在这里，使用我们之前在果蝇中建立的工具包，我们分离了 300 多个重组线粒体基因组，并绘制了细胞色素c氧化酶 III 残基 109 (CoIII ¹⁰⁹ ) 处自然发生的多态性，该多态性完全挽救了与点突变相关的致死性和其他缺陷。细胞色素C氧化酶 I (CoI ^T300I )。通过脂质组学分析、生化测定和表型分析，我们表明 CoIII ¹⁰⁹多态性调节心磷脂结合，以防止 CoI ^T300I突变引起的复合物 IV 不稳定。这项研究证明了在动物线粒体 DNA 中进行遗传相互作用筛选的可行性。它揭示了与线粒体 DNA 相关的疾病背后复杂的基因组内相互作用以及它们如何影响疾病的表达。