dnm1 deletion blocks mitochondrial fragmentation in Δfzo1 cells

Mitochondrial division and fusion play critical roles in maintaining functional mitochondria. Fzo1 is an outer mitochondrial membrane GTPase that played an essential role in mitochondrial fusion in budding yeast Saccharomyces cerevisiae. Here, we report the characterization of the Schizosaccharomyces pombe homologue of S. cerevisiae Fzo1p, Fzo1. Disruption of the fzo1 gene in S. pombe results in a fragmented mitochondrial morphology and a dramatically reduced growth on glycerol medium phenotype, indicating that deletion of fzo1 compromises respiratory function. Fluorescence microscopy shows that Fzo1p is located in the mitochondria. Overexpressing Fzo1 from a heterologous promoter induces mitochondrial aggregation. We also find that dnm1 mutations could both block mitochondrial fragmentation and rescue respiration growth defect in Δfzo1 single mutant cells. Our results proposed that a genetic interaction between fzo1 and a balance between division- and fusion-controlled mitochondrial shape and function in S. pombe. This study represents the first report of Fzo1 mediator of mitochondrial fusion in S. pombe.