Mdm36 is a mitochondrial fission-promoting protein in Saccharomyces cerevisiae.
The division of mitochondrial membranes is a complex process mediated by the dynamin-related protein Dnm1 in yeast, acting in concert with several cofactors. We have identified Mdm36 as a mitochondria-associated protein required for efficient mitochondrial division. Deltamdm36 mutants contain highly interconnected mitochondrial networks that strikingly resemble known fission mutants. Furthermore, mitochondrial fission induced by depolymerization of the actin cytoskeleton is blocked in Deltamdm36 mutants, and the number of Dnm1 clusters on mitochondrial tips is reduced. Double mutant analyses indicate that Mdm36 acts antagonistically to fusion-promoting components, such as Fzo1 and Mdm30. The cell cortex-associated protein Num1 was shown previously to interact with Dnm1 and promote mitochondrial fission. We observed that mitochondria are highly motile and that their localization is not restricted to the cell periphery in Deltamdm36 and Deltanum1 mutants. Intriguingly, colocalization of Num1 and Dnm1 is abolished in the absence of Mdm36. These data suggest that Mdm36 is required for mitochondrial division by facilitating the formation of protein complexes containing Dnm1 and Num1 at the cell cortex. We propose a model that Mdm36-dependent formation of cell cortex anchors is required for the generation of tension on mitochondrial membranes to promote mitochondrial fission by Dnm1.
Hammermeister
Miriam
M
Institut für Zellbiologie, Universität Bayreuth, 95440 Bayreuth, Germany.
Schödel
Kerstin
K
Westermann
Benedikt
B
D020558:GTP Phosphohydrolases / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D053140:Organelle Shape; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
C552950:Mdm36 protein, S cerevisiae; D024101:Mitochondrial Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D020558:GTP Phosphohydrolases; C094774:DNM1 protein, S cerevisiae