Limits...
Dnm1p GTPase-mediated mitochondrial fission is a multi-step process requiring the novel integral membrane component Fis1p.

Mozdy AD, McCaffery JM, Shaw JM - J. Cell Biol. (2000)

Bottom Line: Nunnari. 2000.Genetic and morphological evidence indicate that Fis1p, but not Mdv1p, function is required for the proper assembly and distribution of Dnm1p-containing fission complexes on mitochondrial tubules.We propose that mitochondrial fission in yeast is a multi-step process, and that membrane-bound Fis1p is required for the proper assembly, membrane distribution, and function of Dnm1p-containing complexes during fission.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.

ABSTRACT
Yeast Dnm1p is a soluble, dynamin-related GTPase that assembles on the outer mitochondrial membrane at sites where organelle division occurs. Although these Dnm1p-containing complexes are thought to trigger constriction and fission, little is known about their composition and assembly, and molecules required for their membrane recruitment have not been isolated. Using a genetic approach, we identified two new genes in the fission pathway, FIS1 and FIS2. FIS1 encodes a novel, outer mitochondrial membrane protein with its amino terminus exposed to the cytoplasm. Fis1p is the first integral membrane protein shown to participate in a eukaryotic membrane fission event. In a related study (Tieu, Q., and J. Nunnari. 2000. J. Cell Biol. 151:353-365), it was shown that the FIS2 gene product (called Mdv1p) colocalizes with Dnm1p on mitochondria. Genetic and morphological evidence indicate that Fis1p, but not Mdv1p, function is required for the proper assembly and distribution of Dnm1p-containing fission complexes on mitochondrial tubules. We propose that mitochondrial fission in yeast is a multi-step process, and that membrane-bound Fis1p is required for the proper assembly, membrane distribution, and function of Dnm1p-containing complexes during fission.

Show MeSH

Related in: MedlinePlus

fis1 and fis2 mutations cause mitochondrial net formation and suppress glycerol growth defects and mitochondrial fragmentation in fzo1-1. (A) Wild-type (ADM548), fzo1-1 (ADM547), fis1Δ (ADM549), fis1Δ fzo1-1 (ADM550), fis2-5 (ADM752), fis2-5 fzo1-1 (ADM176), dnm1Δ (ADM379), and dnm1Δ fzo1-1 (ADM378) cells were spotted on YPGlycerol and grown at 25° or 37°C for 5 d. The presence/absence of mtDNA nucleoids in each strain was evaluated by DAPI staining (not shown). (B–Q) Morphology of mito-GFP–labeled (pVT100UGFP) mitochondria in (C) wild-type, (E) fzo1-1, (G) fis1Δ, (I) fis1Δ fzo1-1, (K) fis2-5, (M) fis2-5 fzo1-1, (O) dnm1Δ, and (Q) dnm1Δ fzo1-1 cells grown at 37°C. The corresponding differential interference contrast images are shown in B, D, F, H, J, L, N, and P. Bar, 5 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2192649&req=5

Figure 2: fis1 and fis2 mutations cause mitochondrial net formation and suppress glycerol growth defects and mitochondrial fragmentation in fzo1-1. (A) Wild-type (ADM548), fzo1-1 (ADM547), fis1Δ (ADM549), fis1Δ fzo1-1 (ADM550), fis2-5 (ADM752), fis2-5 fzo1-1 (ADM176), dnm1Δ (ADM379), and dnm1Δ fzo1-1 (ADM378) cells were spotted on YPGlycerol and grown at 25° or 37°C for 5 d. The presence/absence of mtDNA nucleoids in each strain was evaluated by DAPI staining (not shown). (B–Q) Morphology of mito-GFP–labeled (pVT100UGFP) mitochondria in (C) wild-type, (E) fzo1-1, (G) fis1Δ, (I) fis1Δ fzo1-1, (K) fis2-5, (M) fis2-5 fzo1-1, (O) dnm1Δ, and (Q) dnm1Δ fzo1-1 cells grown at 37°C. The corresponding differential interference contrast images are shown in B, D, F, H, J, L, N, and P. Bar, 5 μm.

Mentions: Like dnm1 mutations, fis1 and fis2 mutations rescued the fzo1-1 temperature-sensitive mtDNA loss and glycerol growth defects. Mitochondrial networks in wild-type cells retained their mtDNA nucleoids (DAPI staining, not shown) and these cells grew well on medium containing the nonfermentable carbon source glycerol at both 25° and 37°C (Fig. 2 A, WT). In contrast, the fzo1-1 strain failed to grow on glycerol at 37°C where the mitochondrial reticulum fragments and mtDNA is lost (Fig. 2 A, fzo1-1) (Hermann et al. 1998). As reported previously, this mtDNA loss was prevented when mitochondrial fission and fragmentation were blocked by introducing a dnm1Δ mutation into fzo1-1 (Fig. 2 A, dnm1Δ fzo1-1) or fzo1Δ cells (Bleazard et al. 1999). Although the single fis1 and fis2 mutations did not affect glycerol growth in an otherwise wild-type strain (Fig. 2 A, fis1Δ, fis2-5, both mutations suppressed the temperature-sensitive glycerol growth defect (Fig. 2 A, fis1Δ fzo1-1, fis2-5 fzo1-1) and mtDNA loss defect (not shown) of fzo1-1. (Note that fis2-5 is truncated after 191 of 714 amino acids and behaves like a allele.)


Dnm1p GTPase-mediated mitochondrial fission is a multi-step process requiring the novel integral membrane component Fis1p.

Mozdy AD, McCaffery JM, Shaw JM - J. Cell Biol. (2000)

fis1 and fis2 mutations cause mitochondrial net formation and suppress glycerol growth defects and mitochondrial fragmentation in fzo1-1. (A) Wild-type (ADM548), fzo1-1 (ADM547), fis1Δ (ADM549), fis1Δ fzo1-1 (ADM550), fis2-5 (ADM752), fis2-5 fzo1-1 (ADM176), dnm1Δ (ADM379), and dnm1Δ fzo1-1 (ADM378) cells were spotted on YPGlycerol and grown at 25° or 37°C for 5 d. The presence/absence of mtDNA nucleoids in each strain was evaluated by DAPI staining (not shown). (B–Q) Morphology of mito-GFP–labeled (pVT100UGFP) mitochondria in (C) wild-type, (E) fzo1-1, (G) fis1Δ, (I) fis1Δ fzo1-1, (K) fis2-5, (M) fis2-5 fzo1-1, (O) dnm1Δ, and (Q) dnm1Δ fzo1-1 cells grown at 37°C. The corresponding differential interference contrast images are shown in B, D, F, H, J, L, N, and P. Bar, 5 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2192649&req=5

Figure 2: fis1 and fis2 mutations cause mitochondrial net formation and suppress glycerol growth defects and mitochondrial fragmentation in fzo1-1. (A) Wild-type (ADM548), fzo1-1 (ADM547), fis1Δ (ADM549), fis1Δ fzo1-1 (ADM550), fis2-5 (ADM752), fis2-5 fzo1-1 (ADM176), dnm1Δ (ADM379), and dnm1Δ fzo1-1 (ADM378) cells were spotted on YPGlycerol and grown at 25° or 37°C for 5 d. The presence/absence of mtDNA nucleoids in each strain was evaluated by DAPI staining (not shown). (B–Q) Morphology of mito-GFP–labeled (pVT100UGFP) mitochondria in (C) wild-type, (E) fzo1-1, (G) fis1Δ, (I) fis1Δ fzo1-1, (K) fis2-5, (M) fis2-5 fzo1-1, (O) dnm1Δ, and (Q) dnm1Δ fzo1-1 cells grown at 37°C. The corresponding differential interference contrast images are shown in B, D, F, H, J, L, N, and P. Bar, 5 μm.
Mentions: Like dnm1 mutations, fis1 and fis2 mutations rescued the fzo1-1 temperature-sensitive mtDNA loss and glycerol growth defects. Mitochondrial networks in wild-type cells retained their mtDNA nucleoids (DAPI staining, not shown) and these cells grew well on medium containing the nonfermentable carbon source glycerol at both 25° and 37°C (Fig. 2 A, WT). In contrast, the fzo1-1 strain failed to grow on glycerol at 37°C where the mitochondrial reticulum fragments and mtDNA is lost (Fig. 2 A, fzo1-1) (Hermann et al. 1998). As reported previously, this mtDNA loss was prevented when mitochondrial fission and fragmentation were blocked by introducing a dnm1Δ mutation into fzo1-1 (Fig. 2 A, dnm1Δ fzo1-1) or fzo1Δ cells (Bleazard et al. 1999). Although the single fis1 and fis2 mutations did not affect glycerol growth in an otherwise wild-type strain (Fig. 2 A, fis1Δ, fis2-5, both mutations suppressed the temperature-sensitive glycerol growth defect (Fig. 2 A, fis1Δ fzo1-1, fis2-5 fzo1-1) and mtDNA loss defect (not shown) of fzo1-1. (Note that fis2-5 is truncated after 191 of 714 amino acids and behaves like a allele.)

Bottom Line: Nunnari. 2000.Genetic and morphological evidence indicate that Fis1p, but not Mdv1p, function is required for the proper assembly and distribution of Dnm1p-containing fission complexes on mitochondrial tubules.We propose that mitochondrial fission in yeast is a multi-step process, and that membrane-bound Fis1p is required for the proper assembly, membrane distribution, and function of Dnm1p-containing complexes during fission.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.

ABSTRACT
Yeast Dnm1p is a soluble, dynamin-related GTPase that assembles on the outer mitochondrial membrane at sites where organelle division occurs. Although these Dnm1p-containing complexes are thought to trigger constriction and fission, little is known about their composition and assembly, and molecules required for their membrane recruitment have not been isolated. Using a genetic approach, we identified two new genes in the fission pathway, FIS1 and FIS2. FIS1 encodes a novel, outer mitochondrial membrane protein with its amino terminus exposed to the cytoplasm. Fis1p is the first integral membrane protein shown to participate in a eukaryotic membrane fission event. In a related study (Tieu, Q., and J. Nunnari. 2000. J. Cell Biol. 151:353-365), it was shown that the FIS2 gene product (called Mdv1p) colocalizes with Dnm1p on mitochondria. Genetic and morphological evidence indicate that Fis1p, but not Mdv1p, function is required for the proper assembly and distribution of Dnm1p-containing fission complexes on mitochondrial tubules. We propose that mitochondrial fission in yeast is a multi-step process, and that membrane-bound Fis1p is required for the proper assembly, membrane distribution, and function of Dnm1p-containing complexes during fission.

Show MeSH
Related in: MedlinePlus