scholarly journals The class V myosin motor protein, Myo2, plays a major role in mitochondrial motility in Saccharomyces cerevisiae

2008 ◽  
Vol 181 (1) ◽  
pp. 119-130 ◽  
Author(s):  
Katrin Altmann ◽  
Martina Frank ◽  
Daniel Neumann ◽  
Stefan Jakobs ◽  
Benedikt Westermann
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Molecular Mechanisms ◽  
Budding Yeast ◽  
Motor Protein ◽  
Mitochondrial Morphology ◽  
Direct Role ◽  
Class V ◽  
Myosin Motor ◽  
Mitochondrial Motility

The actin cytoskeleton is essential for polarized, bud-directed movement of cellular membranes in Saccharomyces cerevisiae and thus ensures accurate inheritance of organelles during cell division. Also, mitochondrial distribution and inheritance depend on the actin cytoskeleton, though the precise molecular mechanisms are unknown. Here, we establish the class V myosin motor protein, Myo2, as an important mediator of mitochondrial motility in budding yeast. We found that mutants with abnormal expression levels of Myo2 or its associated light chain, Mlc1, exhibit aberrant mitochondrial morphology and loss of mitochondrial DNA. Specific mutations in the globular tail of Myo2 lead to aggregation of mitochondria in the mother cell. Isolated mitochondria lacking functional Myo2 are severely impaired in their capacity to bind to actin filaments in vitro. Time-resolved fluorescence microscopy revealed a block of bud-directed anterograde mitochondrial movement in cargo binding–defective myo2 mutant cells. We conclude that Myo2 plays an important and direct role for mitochondrial motility and inheritance in budding yeast.

scholarly journals Yeast as a Model to Understand Actin-Mediated Cellular Functions in Mammals—Illustrated with Four Actin Cytoskeleton Proteins

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 672 ◽  
Author(s):  
Zain Akram ◽  
Ishtiaq Ahmed ◽  
Heike Mack ◽  
Ramandeep Kaur ◽  
Richard C. Silva ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Molecular Mechanisms ◽  
Budding Yeast ◽  
Animal Cell ◽  
Molecular Genetic ◽  
In Vivo Studies ◽  
Yeast Saccharomyces Cerevisiae ◽  
Higher Eukaryotes

The budding yeast Saccharomyces cerevisiae has an actin cytoskeleton that comprises a set of protein components analogous to those found in the actin cytoskeletons of higher eukaryotes. Furthermore, the actin cytoskeletons of S. cerevisiae and of higher eukaryotes have some similar physiological roles. The genetic tractability of budding yeast and the availability of a stable haploid cell type facilitates the application of molecular genetic approaches to assign functions to the various actin cytoskeleton components. This has provided information that is in general complementary to that provided by studies of the equivalent proteins of higher eukaryotes and hence has enabled a more complete view of the role of these proteins. Several human functional homologues of yeast actin effectors are implicated in diseases. A better understanding of the molecular mechanisms underpinning the functions of these proteins is critical to develop improved therapeutic strategies. In this article we chose as examples four evolutionarily conserved proteins that associate with the actin cytoskeleton: (1) yeast Hof1p/mammalian PSTPIP1, (2) yeast Rvs167p/mammalian BIN1, (3) yeast eEF1A/eEF1A1 and eEF1A2 and (4) yeast Yih1p/mammalian IMPACT. We compare the knowledge on the functions of these actin cytoskeleton-associated proteins that has arisen from studies of their homologues in yeast with information that has been obtained from in vivo studies using live animals or in vitro studies using cultured animal cell lines.

Association of the class V myosin Myo4p with a localised messenger RNA in budding yeast depends on She proteins

1999 ◽  
Vol 112 (10) ◽  
pp. 1511-1518 ◽  
Author(s):  
S. Munchow ◽  
C. Sauter ◽  
R.P. Jansen
Keyword(s):  
Messenger Rna ◽  
Budding Yeast ◽  
Motor Protein ◽  
Specific Protein ◽  
Asymmetric Distribution ◽  
Messenger Rnas ◽  
Direct Role ◽  
Mating Type Switching ◽  
Type V ◽  
Ash1 Mrna

Asymmetric distribution of messenger RNAs is a widespread mechanism to localize synthesis of specific protein to distinct sites in the cell. Although not proven yet there is considerable evidence that mRNA localisation is an active process that depends on the activity of cytoskeletal motor proteins. To date, the only motor protein with a specific role in mRNA localisation is the budding yeast type V myosin Myo4p. Myo4p is required for the localisation of ASH1 mRNA, encoding a transcriptional repressor that is essential for differential expression of the HO gene and mating type switching in budding yeast. Mutations in Myo4p, in proteins of the actin cytoskeleton, and in four other specific genes, SHE2-SHE5 disrupt the daughter-specific localisation of ASH1 mRNA. In order to understand if Myo4p is directly participating in mRNA transport, we used in situ colocalisation and coprecipitation of Myo4p and ASH1 mRNA to test for their interaction. Our results indicate an association of Myo4p and ASH1 mRNA that depends on the activity of two other genes involved in ASH1 mRNA localisation, SHE2 and SHE3. This strongly suggests a direct role of Myo4p myosin as a transporter of localised mRNAs, convincingly supporting the concept of motor-protein based mRNA localisation.

scholarly journals Skp1p and the F-Box Protein Rcy1p Form a Non-SCF Complex Involved in Recycling of the SNARE Snc1p in Yeast

2001 ◽  
Vol 21 (9) ◽  
pp. 3105-3117 ◽  
Author(s):  
Jean-Marc Galan ◽  
Andreas Wiederkehr ◽  
Jae Hong Seol ◽  
Rosine Haguenauer-Tsapis ◽  
Raymond J. Deshaies ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Substrate Specificity ◽  
Actin Cytoskeleton ◽  
Dependent Manner ◽  
Polarized Growth ◽  
Core Complex ◽  
Direct Role ◽  
Scf Complex ◽  
F Box Protein

ABSTRACT Skp1p–cullin–F-box protein (SCF) complexes are ubiquitin-ligases composed of a core complex including Skp1p, Cdc53p, Hrt1p, the E2 enzyme Cdc34p, and one of multiple F-box proteins which are thought to provide substrate specificity to the complex. Here we show that the F-box protein Rcy1p is required for recycling of the v-SNARE Snc1p inSaccharomyces cerevisiae. Rcy1p localized to areas of polarized growth, and this polarized localization required its CAAX box and an intact actin cytoskeleton. Rcy1p interacted with Skp1p in vivo in an F-box-dependent manner, and both deletion of its F box and loss of Skp1p function impaired recycling. In contrast, cells deficient in Cdc53p, Hrt1p, or Cdc34p did not exhibit recycling defects. Unlike the case for F-box proteins that are known to participate in SCF complexes, degradation of Rcy1p required neither its F box nor functional 26S proteasomes or other SCF core subunits. Importantly, Skp1p was the only major partner that copurified with Rcy1p. Our results thus suggest that a complex composed of Rcy1p and Skp1p but not other SCF components may play a direct role in recycling of internalized proteins.

scholarly journals Rvs161p Interacts with Fus2p to Promote Cell Fusion in Saccharomyces cerevisiae

1998 ◽  
Vol 141 (3) ◽  
pp. 567-584 ◽  
Author(s):  
Valeria Brizzio ◽  
Alison E. Gammie ◽  
Mark D. Rose
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Fusion Zone ◽  
Cell Fusion ◽  
Direct Role ◽  
Cytoskeletal Organization ◽  
Actin Organization ◽  
The Stability ◽  
Mating Function ◽  
Lines Of Evidence

FUS7 was previously identified by a mutation that causes a defect in cell fusion in a screen for bilateral mating defects. Here we show that FUS7 is allelic to RVS161/END6, a gene implicated in a variety of processes including viability after starvation, endocytosis, and actin cytoskeletal organization. Two lines of evidence indicate that RVS161/END6's endocytic function is not required for cell fusion. First, several other endocytic mutants showed no cell fusion defects. Second, we isolated five function-specific alleles of RVS161/FUS7 that were defective for endocytosis, but not mating, and three alleles that were defective for cell fusion but not endocytosis. The organization of the actin cytoskeleton was normal in the cell fusion mutants, indicating that Rvs161p's function in cell fusion is independent of actin organization. The three to fourfold induction of RVS161 by mating pheromone and the localization of Rvs161p-GFP to the cell fusion zone suggested that Rvs161p plays a direct role in cell fusion. The phenotypes of double mutants, the coprecipitation of Rvs161p and Fus2p, and the fact that the stability of Fus2p was strongly dependent on Rvs161p's mating function lead to the conclusion that Rvs161p is required to interact with Fus2p for efficient cell fusion.

scholarly journals CsmA, a Class V Chitin Synthase with a Myosin Motor-like Domain, Is Localized through Direct Interaction with the Actin Cytoskeleton inAspergillus nidulans

2005 ◽  
Vol 16 (4) ◽  
pp. 1961-1970 ◽  
Author(s):  
Norio Takeshita ◽  
Akinori Ohta ◽  
Hiroyuki Horiuchi
Keyword(s):  
Cell Wall ◽  
Actin Cytoskeleton ◽  
Direct Interaction ◽  
Chitin Synthase ◽  
Structural Basis ◽  
Class V ◽  
Myosin Motor ◽  
Fungal Morphogenesis ◽  
Insight Into

One of the essential features of fungal morphogenesis is the polarized synthesis of cell wall components such as chitin. The actin cytoskeleton provides the structural basis for cell polarity in Aspergillus nidulans, as well as in most other eukaryotes. A class V chitin synthase, CsmA, which contains a myosin motor-like domain (MMD), is conserved among most filamentous fungi. The ΔcsmA null mutant showed remarkable abnormalities with respect to cell wall integrity and the establishment of polarity. In this study, we demonstrated that CsmA tagged with 9× HA epitopes localized near actin structures at the hyphal tips and septation sites and that its MMD was able to bind to actin. Characterization of mutants bearing a point mutation or deletion in the MMD suggests that the interaction between the MMD and actin is not only necessary for the proper localization of CsmA, but also for CsmA function. Thus, the finding of a direct interaction between the chitin synthase and the actin cytoskeleton provides new insight into the mechanisms of polarized cell wall synthesis and fungal morphogenesis.

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