Mitochondrial morphology is a result of regulated opposite events called fission and fusion and requires the GTPase, dynamin-related protein 1 (DRP1/Dnm1), or its homologs. A recent clinical report identified a heterozygous missense mutation in the human DRP1 that replaces Glycine (G) 149 with Arginine (R) and results in debilitating conditions in the patient. In this study, we mimicked this mutation in yeast Dnm1 (G178R) and investigated the impact of the pathogenic mutation on the protein's function. We provide evidence that the substitution of G with R in the G3 motif of the GTPase domain, renders the protein non-functional and in a dominant-negative way. The mutation hampers the distribution, localization, and function of the protein. Cells expressing the mutant variant exhibit a block in mitochondrial fission and altered peroxisome morphology and number.