scholarly journals The myosin-related motor protein Myo2 is an essential mediator of bud-directed mitochondrial movement in yeast

2011 ◽  
Vol 194 (3) ◽  
pp. 473-488 ◽  
Author(s):  
Johannes Förtsch ◽  
Eric Hummel ◽  
Melanie Krist ◽  
Benedikt Westermann
Keyword(s):  
Synthetic Lethality ◽  
Motor Protein ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Gene Encoding ◽  
Mitochondrial Movement ◽  
Isolated Mitochondria ◽  
Mitochondrial Distribution ◽  
Synthetically Lethal ◽  
Guanosine Triphosphatase

The inheritance of mitochondria in yeast depends on bud-directed transport along actin filaments. It is a matter of debate whether anterograde mitochondrial movement is mediated by the myosin-related motor protein Myo2 or by motor-independent mechanisms. We show that mutations in the Myo2 cargo binding domain impair entry of mitochondria into the bud and are synthetically lethal with deletion of the YPT11 gene encoding a rab-type guanosine triphosphatase. Mitochondrial distribution defects and synthetic lethality were rescued by a mitochondria-specific Myo2 variant that carries a mitochondrial outer membrane anchor. Furthermore, immunoelectron microscopy revealed Myo2 on isolated mitochondria. Thus, Myo2 is an essential and direct mediator of bud-directed mitochondrial movement in yeast. Accumulating genetic evidence suggests that maintenance of mitochondrial morphology, Ypt11, and retention of mitochondria in the bud contribute to Myo2-dependent inheritance of mitochondria.

scholarly journals The Yeast Dynamin-like Protein, Mgm1p, Functions on the Mitochondrial Outer Membrane to Mediate Mitochondrial Inheritance

1999 ◽  
Vol 144 (4) ◽  
pp. 711-720 ◽  
Author(s):  
Kelly A. Shepard ◽  
Michael P. Yaffe
Keyword(s):  
Mitochondrial Genome ◽  
Outer Membrane ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Mitochondrial Inheritance ◽  
Gene Encoding ◽  
Yeast Saccharomyces Cerevisiae ◽  
High Molecular Weight Complex ◽  
Mitochondrial Distribution ◽  
Mutant Phenotypes

The mdm17 mutation causes temperature-dependent defects in mitochondrial inheritance, mitochondrial morphology, and the maintenance of mitochondrial DNA in the yeast Saccharomyces cerevisiae. Defects in mitochondrial transmission to daughter buds and changes in mitochondrial morphology were apparent within 30 min after shifting cells to 37°C, while loss of the mitochondrial genome occurred after 4–24 h at the elevated temperature. The mdm17 lesion mapped to MGM1, a gene encoding a dynamin-like GTPase previously implicated in mitochondrial genome maintenance, and the cloned MGM1 gene complements all of the mdm17 mutant phenotypes. Cells with an mgm1-null mutation displayed aberrant mitochondrial inheritance and morphology. A version of mgm1 mutated in a conserved residue in the putative GTP-binding site was unable to complement any of the mutant defects. It also caused aberrant mitochondrial distribution and morphology when expressed at high levels in cells that also contained a wild-type copy of the gene. Mgm1p was localized to the mitochondrial outer membrane and fractionated as a component of a high molecular weight complex. These results indicate that Mgm1p is a mitochondrial inheritance and morphology component that functions on the mitochondrial surface.

scholarly journals Prohibitin Family Members Interact Genetically with Mitochondrial Inheritance Components in Saccharomyces cerevisiae

1998 ◽  
Vol 18 (7) ◽  
pp. 4043-4052 ◽  
Author(s):  
Karen H. Berger ◽  
Michael P. Yaffe
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Outer Membrane ◽  
Integral Membrane Proteins ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Mitochondrial Inheritance ◽  
Loss Of Function ◽  
Wild Type ◽  
Mitochondrial Inner Membrane ◽  
Synthetically Lethal

ABSTRACT Phb2p, a homolog of the tumor suppressor protein prohibitin, was identified in a genetic screen for suppressors of the loss of Mdm12p, a mitochondrial outer membrane protein required for normal mitochondrial morphology and inheritance in Saccharomyces cerevisiae. Phb2p and its homolog, prohibitin (Phb1p), were localized to the mitochondrial inner membrane and characterized as integral membrane proteins which depend on each other for their stability. In otherwise wild-type genetic backgrounds, null mutations in PHB1 andPHB2 did not confer any obvious phenotypes. However, loss of function of either PHB1 or PHB2 in cells with mitochondrial DNA deleted led to altered mitochondrial morphology, and phb1 or phb2 mutations were synthetically lethal when combined with a mutation in any of three mitochondrial inheritance components of the mitochondrial outer membrane, Mdm12p, Mdm10p, and Mmm1p. These results provide the first evidence of a role for prohibitin in mitochondrial inheritance and in the regulation of mitochondrial morphology.

scholarly journals GCS1, an Arf Guanosine Triphosphatase-activating Protein in Saccharomyces cerevisiae, Is Required for Normal Actin Cytoskeletal Organization In Vivo and Stimulates Actin Polymerization In Vitro

1999 ◽  
Vol 10 (3) ◽  
pp. 581-596 ◽  
Author(s):  
Ira J. Blader ◽  
M. Jamie T. V. Cope ◽  
Trevor R. Jackson ◽  
Adam A. Profit ◽  
Angela F. Greenwood ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
Synthetic Lethality ◽  
Null Alleles ◽  
Gene Encoding ◽  
Amino Terminal ◽  
Guanosine Triphosphatase

Recent cloning of a rat brain phosphatidylinositol 3,4,5-trisphosphate binding protein, centaurin α, identified a novel gene family based on homology to an amino-terminal zinc-binding domain. In Saccharomyces cerevisiae, the protein with the highest homology to centaurin α is Gcs1p, the product of theGCS1 gene. GCS1 was originally identified as a gene conditionally required for the reentry of cells into the cell cycle after stationary phase growth. Gcs1p was previously characterized as a guanosine triphosphatase-activating protein for the small guanosine triphosphatase Arf1, and gcs1 mutants displayed vesicle-trafficking defects. Here, we have shown that similar to centaurin α, recombinant Gcs1p bound phosphoinositide-based affinity resins with high affinity and specificity. A novelGCS1 disruption strain (gcs1Δ) exhibited morphological defects, as well as mislocalization of cortical actin patches. gcs1Δ was hypersensitive to the actin monomer-sequestering drug, latrunculin-B. Synthetic lethality was observed between null alleles of GCS1 andSLA2, the gene encoding a protein involved in stabilization of the actin cytoskeleton. In addition, synthetic growth defects were observed between null alleles of GCS1 andSAC6, the gene encoding the yeast fimbrin homologue. Recombinant Gcs1p bound to actin filaments, stimulated actin polymerization, and inhibited actin depolymerization in vitro. These data provide in vivo and in vitro evidence that Gcs1p interacts directly with the actin cytoskeleton in S. cerevisiae.

scholarly journals Regulation of mitochondrial morphology and inheritance by Mdm10p, a protein of the mitochondrial outer membrane.

1994 ◽  
Vol 126 (6) ◽  
pp. 1361-1373 ◽  
Author(s):  
L F Sogo ◽  
M P Yaffe
Keyword(s):  
Outer Membrane ◽  
Yeast Cells ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Wild Type ◽  
Giant Mitochondria ◽  
Mitochondrial Distribution ◽  
Rapid Restoration ◽  
Mutant Phenotypes ◽  
Mutant Cells

Yeast cells with the mdm10 mutation possess giant spherical mitochondria and are defective for mitochondrial inheritance. The giant mitochondria display classical features of mitochondrial ultrastructure, yet they appear incapable of movement or division. Genetic analysis indicated that the mutant phenotypes resulted from a single nuclear mutation, and the isolated MDM10 gene restored wild-type mitochondrial distribution and morphology when introduced into mutant cells. MDM10 encodes a protein of 56.2 kD located in the mitochondrial outer membrane. Depletion of Mdm10p from cells led to a condensation of normally extended, tubular mitochondria into giant spheres, and reexpression of the protein resulted in a rapid restoration of normal mitochondrial morphology. These results demonstrate that Mdm10p can control mitochondrial morphology, and that it plays a role in the inheritance of mitochondria.

scholarly journals A Protein Complex Containing Mdm10p, Mdm12p, and Mmm1p Links Mitochondrial Membranes and DNA to the Cytoskeleton-based Segregation Machinery

2003 ◽  
Vol 14 (11) ◽  
pp. 4618-4627 ◽  
Author(s):  
Istvan R. Boldogh ◽  
Dan W. Nowakowski ◽  
Hyeong-Cheol Yang ◽  
Haesung Chung ◽  
Sharon Karmon ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Reciprocal Relationship ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Mitochondrial Movement ◽  
Close Proximity ◽  
Mtdna Deletion ◽  
Mitochondrial Motility ◽  
In Cells

Previous studies indicate that two proteins, Mmm1p and Mdm10p, are required to link mitochondria to the actin cytoskeleton of yeast and for actin-based control of mitochondrial movement, inheritance and morphology. Both proteins are integral mitochondrial outer membrane proteins. Mmm1p localizes to punctate structures in close proximity to mitochondrial DNA (mtDNA) nucleoids. We found that Mmm1p and Mdm10p exist in a complex with Mdm12p, another integral mitochondrial outer membrane protein required for mitochondrial morphology and inheritance. This interpretation is based on observations that 1) Mdm10p and Mdm12p showed the same localization as Mmm1p; 2) Mdm12p, like Mdm10p and Mmm1p, was required for mitochondrial motility; and 3) all three proteins coimmunoprecipitated with each other. Moreover, Mdm10p localized to mitochondria in the absence of the other subunits. In contrast, deletion of MMM1 resulted in mislocalization of Mdm12p, and deletion of MDM12 caused mislocalization of Mmm1p. Finally, we observed a reciprocal relationship between the Mdm10p/Mdm12p/Mmm1p complex and mtDNA. Deletion of any one of the subunits resulted in loss of mtDNA or defects in mtDNA nucleoid maintenance. Conversely, deletion of mtDNA affected mitochondrial motility: mitochondria in cells without mtDNA move 2–3 times faster than mitochondria in cells with mtDNA. These observations support a model in which the Mdm10p/Mdm12p/Mmm1p complex links the minimum heritable unit of mitochondria (mtDNA and mitochondrial outer and inner membranes) to the cytoskeletal system that drives transfer of that unit from mother to daughter cells.

scholarly journals The Yeast Gene, MDM20, Is Necessary for Mitochondrial Inheritance and Organization of the Actin Cytoskeleton

1997 ◽  
Vol 137 (1) ◽  
pp. 141-153 ◽  
Author(s):  
Greg J. Hermann ◽  
Edward J. King ◽  
Janet M. Shaw
Keyword(s):  
Actin Cytoskeleton ◽  
Synthetic Lethality ◽  
Mitochondrial Inheritance ◽  
Gene Encoding ◽  
Mutant Strains ◽  
Polarized Transport ◽  
Synthetically Lethal ◽  
Mutant Phenotypes ◽  
Actin Cables

In Saccharomyces cerevisiae, the growing bud inherits a portion of the mitochondrial network from the mother cell soon after it emerges. Although this polarized transport of mitochondria is thought to require functions of the cytoskeleton, there are conflicting reports concerning the nature of the cytoskeletal element involved. Here we report the isolation of a yeast mutant, mdm20, in which both mitochondrial inheritance and actin cables (bundles of actin filaments) are disrupted. The MDM20 gene encodes a 93-kD polypeptide with no homology to other characterized proteins. Extra copies of TPM1, a gene encoding the actin filament–binding protein tropomyosin, suppress mitochondrial inheritance defects and partially restore actin cables in mdm20Δ cells. Synthetic lethality is also observed between mdm20 and tpm1 mutant strains. Overexpression of a second yeast tropomyosin, Tpm2p, rescues mutant phenotypes in the mdm20 strain to a lesser extent. Together, these results provide compelling evidence that mitochondrial inheritance in yeast is an actin-mediated process. MDM20 and TPM1 also exhibit the same pattern of genetic interactions; mutations in MDM20 are synthetically lethal with mutations in BEM2 and MYO2 but not SAC6. Although MDM20 and TPM1 are both required for the formation and/or stabilization of actin cables, mutations in these genes disrupt mitochondrial inheritance and nuclear segregation to different extents. Thus, Mdm20p and Tpm1p may act in vivo to establish molecular and functional heterogeneity of the actin cytoskeleton.

scholarly journals Puf3p, a Pumilio family RNA binding protein, localizes to mitochondria and regulates mitochondrial biogenesis and motility in budding yeast

2007 ◽  
Vol 176 (2) ◽  
pp. 197-207 ◽  
Author(s):  
Luis J. García-Rodríguez ◽  
Anna Card Gay ◽  
Liza A. Pon
Keyword(s):  
Mitochondrial Biogenesis ◽  
Rna Binding ◽  
Mitochondrial Protein ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Diauxic Shift ◽  
Messenger Rnas ◽  
Mitochondrial Movement ◽  
Nonfermentable Carbon Source ◽  
Force Generator

Puf3p binds preferentially to messenger RNAs (mRNAs) for nuclear-encoded mitochondrial proteins. We find that Puf3p localizes to the cytosolic face of the mitochondrial outer membrane. Overexpression of PUF3 results in reduced mitochondrial respiratory activity and reduced levels of Pet123p, a protein encoded by a Puf3p-binding mRNA. Puf3p levels are reduced during the diauxic shift and growth on a nonfermentable carbon source, conditions that stimulate mitochondrial biogenesis. These findings support a role for Puf3p in mitochondrial biogenesis through effects on mRNA interactions. In addition, Puf3p links the mitochore, a complex required for mitochondrial–cytoskeletal interactions, to the Arp2/3 complex, the force generator for actin-dependent, bud-directed mitochondrial movement. Puf3p, the mitochore, and the Arp2/3 complex coimmunoprecipitate and have two-hybrid interactions. Moreover, deletion of PUF3 results in reduced interaction between the mitochore and the Arp2/3 complex and defects in mitochondrial morphology and motility similar to those observed in Arp2/3 complex mutants. Thus, Puf3p is a mitochondrial protein that contributes to the biogenesis and motility of the organelle.

scholarly journals Gag3p, an Outer Membrane Protein Required for Fission of Mitochondrial Tubules

2000 ◽  
Vol 151 (2) ◽  
pp. 333-340 ◽  
Author(s):  
Peter Fekkes ◽  
Kelly A. Shepard ◽  
Michael P. Yaffe
Keyword(s):  
Outer Membrane ◽  
Mitochondrial Fission ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Gene Products ◽  
Mitochondrial Fragmentation ◽  
Gene Encoding ◽  
Peripheral Protein ◽  
And Function ◽  
Two Hybrid

Mitochondrial morphology and function depend on MGM1, a Saccharomyces cerevisiae gene encoding a dynamin-like protein of the mitochondrial outer membrane. Here, we show that mitochondrial fragmentation and mitochondrial genome loss caused by lesions in MGM1 are suppressed by three novel mutations, gag1, gag2, and gag3 (for glycerol-adapted growth). Cells with any of the gag mutations displayed aberrant mitochondrial morphology characterized by elongated, unbranched tubes and highly fenestrated structures. Additionally, each of the gag mutations prevented mitochondrial fragmentation caused by loss of the mitochondrial fusion factor, Fzo1p, or by treatment of cells with sodium azide. The gag1 mutation mapped to DNM1 that encodes a dynamin-related protein required for mitochondrial fission. GAG3 encodes a novel WD40-repeat protein previously found to interact with Dnm1p in a two-hybrid assay. Gag3p was localized to mitochondria where it was found to associate as a peripheral protein on the cytosolic face of the outer membrane. This association requires neither the DNM1 nor GAG2 gene products. However, the localization of Dnm1p to the mitochondrial outer membrane is substantially reduced by the gag2 mutation, but unaffected by loss of Gag3p. These results indicate that Gag3p plays a distinct role on the mitochondrial surface to mediate the fission of mitochondrial tubules.

scholarly journals Suppressors of a Saccharomyces cerevisiae pkc1 mutation identify alleles of the phosphatase gene PTC1 and of a novel gene encoding a putative basic leucine zipper protein.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1275-1285 ◽  
Author(s):  
K N Huang ◽  
L S Symington
Keyword(s):  
Protein Kinase ◽  
Leucine Zipper ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Gene Encoding ◽  
Basic Leucine Zipper ◽  
Mapk Cascades ◽  
Synthetically Lethal

Abstract The PKC1 gene product, protein kinase C, regulates a mitogen-activated protein kinase (MAPK) cascade, which is implicated in cell wall metabolism. Previously, we identified the pkc1-4 allele in a screen for mutants with increased rates of recombination, indicating that PKC1 may also regulate DNA metabolism. The pkc1-4 allele also conferred a temperature-sensitive (ts) growth defect. Extragenic suppressors were isolated that suppress both the ts and hyperrecombination phenotypes conferred by the pkc1-4 mutation. Eight of these suppressors for into two complementation groups, designated KCS1 and KCS2. KCS1 was cloned and found to encode a novel protein with homology to the basic leucine zipper family of transcription factors. KCS2 is allelic with PTC1, a previously identified type 2C serine/threonine protein phosphatase. Although mutation of either KCS1 or PTC1 causes little apparent phenotype, the kcs1 delta ptc1 delta double mutant fails to grow at 30 degrees. Furthermore, the ptc1 deletion mutation is synthetically lethal in combination with a mutation in MPK1, which encodes a MAPK homologue proposed to act in the PKC1 pathway. Because PTC1 was initially isolated as a component of the Hog1p MAPK pathway, it appears that these two MAPK cascades share a common regulatory feature.

Overproduction of yeast viruslike particles by strains deficient in a mitochondrial nuclease

1989 ◽  
Vol 9 (8) ◽  
pp. 3323-3331
Author(s):  
Y X Liu ◽  
C L Dieckmann
Keyword(s):  
Coat Protein ◽  
Killer Toxin ◽  
Nuclear Gene ◽  
Fold Increase ◽  
Mitochondrial Outer Membrane ◽  
Gene Encoding ◽  
Recessive Mutations ◽  
A Genome ◽  
Nonfermentable Carbon Source ◽  
Viruslike Particles

Saccharomyces cerevisiae strains are often host to several types of cytoplasmic double-stranded RNA (dsRNA) genomes, some of which are encapsidated by the L-A dsRNA product, an 86,000-dalton coat protein. Here we present the finding that nuclear recessive mutations in the NUC1 gene, which encodes the major nonspecific nuclease of yeast mitochondria, resulted in at least a 10-fold increase in amounts of the L-A dsRNA and its encoded coat protein. The effect of nuc1 mutations on L-A abundance was completely suppressed in strains that also hosted the killer-toxin-encoding M dsRNA. Both NUC1 and nuc1 strains containing the L-A genome exhibited an increase in coat protein abundance and a concomitant increase in L-A dsRNA when the cells were grown on a nonfermentable carbon source rather than on glucose, an effect independent of the increase in coat protein due to nuc1 mutations or to the absence of M. The increase in L-A expression in nuc1 strains was similar to that observed in strains with mutations in the nuclear gene encoding the most abundant outer mitochondrial membrane protein, porin. nuc1 mutations did not affect the level of porin in the mitochondrial outer membrane. Since the effect of mutations in nuc1 was to alter the copy number of the L-A coat protein genome rather than to change the level of the M toxin genome (as do mak and ski mutations), these mutations define a new class of nuclear genes affecting yeast dsRNA abundance.

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