Chemical genetic interaction linking eIF5A hypusination and mitochondrial integrity

The eukaryotic translation factor eIF5A plays an important role in translation elongation, especially across stretches of prolines and charged amino acids, and in translation termination. eIF5A undergoes hypusination, a post-translational modification unique to this protein, although the role of hypusination in the function of eIF5A remains elusive. Here, we investigated the cellular defects induced by the hypusination inhibitor GC7 (N1-guanyl-1,7-diaminoheptane). Proteome, translatome, and transcriptome analyses indicated that GC7 downregulated a subset of mitochondrial proteins and DNA, causing mitochondrial stress and eliciting the integrated stress response. Chemical genomic screening using barcoded shRNA libraries identified genes encoding proteins involved in polyamine metabolism/transport and MPV17L2, a mitochondrial disease gene homologue whose product regulates mitochondrial translation. Depletion of MPV17L2 caused hypersensitivity to GC7 and phenocopied the effects of GC7 treatment. These results suggest that eIF5A hypusination and MPV17L2 synthetically regulate mitochondrial molecular synthesis and integrity.