scholarly journals Mmm2p, a mitochondrial outer membrane protein required for yeast mitochondrial shape and maintenance of mtDNA nucleoids

2004 ◽  
Vol 164 (5) ◽  
pp. 677-688 ◽  
Author(s):  
Matthew J. Youngman ◽  
Alyson E. Aiken Hobbs ◽  
Shawn M. Burgess ◽  
Maithreyan Srinivasan ◽  
Robert E. Jensen
Keyword(s):  
Mitochondrial Dna ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Mitochondrial Outer Membrane ◽  
Dynamic Interactions ◽  
Cell Biol

The mitochondrial outer membrane protein, Mmm1p, is required for normal mitochondrial shape in yeast. To identify new morphology proteins, we isolated mutations incompatible with the mmm1-1 mutant. One of these mutants, mmm2-1, is defective in a novel outer membrane protein. Lack of Mmm2p causes a defect in mitochondrial shape and loss of mitochondrial DNA (mtDNA) nucleoids. Like the Mmm1 protein (Aiken Hobbs, A.E., M. Srinivasan, J.M. McCaffery, and R.E. Jensen. 2001. J. Cell Biol. 152:401–410.), Mmm2p is located in dot-like particles on the mitochondrial surface, many of which are adjacent to mtDNA nucleoids. While some of the Mmm2p-containing spots colocalize with those containing Mmm1p, at least some of Mmm2p is separate from Mmm1p. Moreover, while Mmm2p and Mmm1p both appear to be part of large complexes, we find that Mmm2p and Mmm1p do not stably interact and appear to be members of two different structures. We speculate that Mmm2p and Mmm1p are components of independent machinery, whose dynamic interactions are required to maintain mitochondrial shape and mtDNA structure.

scholarly journals Mutations in Fis1 disrupt orderly disposal of defective mitochondria

2014 ◽  
Vol 25 (1) ◽  
pp. 145-159 ◽  
Author(s):  
Qinfang Shen ◽  
Koji Yamano ◽  
Brian P. Head ◽  
Sumihiro Kawajiri ◽  
Jesmine T. M. Cheung ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Couple Stress ◽  
Mitochondrial Fission ◽  
Mitochondrial Outer Membrane ◽  
Related Protein ◽  
Degradation Processes ◽  
Mitochondrial Toxins

Mitochondrial fission is mediated by the dynamin-related protein Drp1 in metazoans. Drp1 is recruited from the cytosol to mitochondria by the mitochondrial outer membrane protein Mff. A second mitochondrial outer membrane protein, named Fis1, was previously proposed as recruitment factor, but Fis1−/− cells have mild or no mitochondrial fission defects. Here we show that Fis1 is nevertheless part of the mitochondrial fission complex in metazoan cells. During the fission cycle, Drp1 first binds to Mff on the surface of mitochondria, followed by entry into a complex that includes Fis1 and endoplasmic reticulum (ER) proteins at the ER–mitochondrial interface. Mutations in Fis1 do not normally affect fission, but they can disrupt downstream degradation events when specific mitochondrial toxins are used to induce fission. The disruptions caused by mutations in Fis1 lead to an accumulation of large LC3 aggregates. We conclude that Fis1 can act in sequence with Mff at the ER–mitochondrial interface to couple stress-induced mitochondrial fission with downstream degradation processes.

scholarly journals Multispan mitochondrial outer membrane protein Ugo1 follows a unique Mim1-dependent import pathway

2011 ◽  
Vol 194 (3) ◽  
pp. 397-405 ◽  
Author(s):  
Dražen Papić ◽  
Katrin Krumpe ◽  
Jovana Dukanovic ◽  
Kai S. Dimmer ◽  
Doron Rapaport
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Gel Electrophoresis ◽  
Mitochondrial Outer Membrane ◽  
Yeast Mitochondria ◽  
Membrane Complex ◽  
Native Gel ◽  
Insertion Process ◽  
Import Receptor

The mitochondrial outer membrane (MOM) harbors several multispan proteins that execute various functions. Despite their importance, the mechanisms by which these proteins are recognized and inserted into the outer membrane remain largely unclear. In this paper, we address this issue using yeast mitochondria and the multispan protein Ugo1. Using a specific insertion assay and analysis by native gel electrophoresis, we show that the import receptor Tom70, but not its partner Tom20, is involved in the initial recognition of the Ugo1 precursor. Surprisingly, the import pore formed by the translocase of the outer membrane complex appears not to be required for the insertion process. Conversely, the multifunctional outer membrane protein mitochondrial import 1 (Mim1) plays a central role in mediating the insertion of Ugo1. Collectively, these results suggest that Ugo1 is inserted into the MOM by a novel pathway in which Tom70 and Mim1 contribute to the efficiency and selectivity of the process.

scholarly journals A Novel Isoform of the Mitochondrial Outer Membrane Protein VDAC3 via Alternative Splicing of a 3-Base Exon

1998 ◽  
Vol 273 (46) ◽  
pp. 30482-30486 ◽  
Author(s):  
Margaret J. Sampson ◽  
Lyle Ross ◽  
William K. Decker ◽  
William J. Craigen
Keyword(s):  
Alternative Splicing ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Mitochondrial Outer Membrane
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