Identification of Myo3, a second type‐II myosin heavy chain in the fission yeast <i>Schizosaccharomyces pombe</i>

Motegi, Fumio; Nakano, Kentaro; Kitayama, Chikako; Yamamoto, Masayuki; Mabuchi, Issei

doi:10.1016/s0014-5793(97)01510-x

Cited by 81 publications

(84 citation statements)

References 22 publications

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“…However, one significant difference is in the relative importance of the actomyosin contractile ring during cytokinesis. Although myosin II and the contractile ring are essential for cytokinesis in S. pombe (Bezanilla et al, 1997;Kitayama et al, 1997;May et al, 1997;Motegi et al, 1997), they are not essential in S. cerevisiae (Bi et al, 1998;Lippincott and Li, 1998). A possible explanation for this difference is that the primary role of the contractile ring is to guide septum deposition (Hales et al, 1999;Vallen et al, 2000) and that the need for such guidance is greater in forming the ϳ3-m-diameter septum in S. pombe than in forming the ϳ1-m-diameter septum in S. cerevisiae.…”

Section: Evolution and Functional Relationships Of Actinbundling Protmentioning

confidence: 99%

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Roles of a Fimbrin and an α-Actinin-like Protein in Fission Yeast Cell Polarization and Cytokinesis

Bähler

Pringle

2001

MBoC

146

183

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Eukaryotic cells contain many actin-interacting proteins, including the ␣-actinins and the fimbrins, both of which have actin cross-linking activity in vitro. We report here the identification and characterization of both an ␣-actinin-like protein (Ain1p) and a fimbrin (Fim1p) in the fission yeast Schizosaccharomyces pombe. Ain1p localizes to the actomyosin-containing medial ring in an F-actindependent manner, and the Ain1p ring contracts during cytokinesis. ain1 deletion cells have no obvious defects under normal growth conditions but display severe cytokinesis defects, associated with defects in medial-ring and septum formation, under certain stress conditions. Overexpression of Ain1p also causes cytokinesis defects, and the ain1 deletion shows synthetic effects with other mutations known to affect medial-ring positioning and/or organization. Fim1p localizes both to the cortical actin patches and to the medial ring in an F-actin-dependent manner, and several lines of evidence suggest that Fim1p is involved in polarization of the actin cytoskeleton. Although a fim1 deletion strain has no detectable defect in cytokinesis, overexpression of Fim1p causes a lethal cytokinesis defect associated with a failure to form the medial ring and concentrate actin patches at the cell middle. Moreover, an ain1 fim1 double mutant has a synthetical-lethal defect in medial-ring assembly and cell division. Thus, Ain1p and Fim1p appear to have an overlapping and essential function in fission yeast cytokinesis. In addition, protein-localization and mutant-phenotype data suggest that Fim1p, but not Ain1p, plays important roles in mating and in spore formation. INTRODUCTIONThe actin cytoskeleton is involved in many processes in eukaryotic cells, including the polarization of cell growth and cytokinesis. These many roles involve the interaction of actin with a wide variety of actin-binding proteins, including proteins that can cross-link actin filaments into isotropic gels or bundles. Many actin cross-linking proteins have been purified and studied in vitro, but their functions in vivo remain poorly understood (reviewed by Matsudaira, 1994a;Otto, 1994;Furukawa and Fechheimer, 1997;Ayscough, 1998;Bartles, 2000).Among the actin cross-linking proteins, one of the best characterized is ␣-actinin. It was first isolated from rabbit skeletal muscle (Ebashi and Ebashi, 1965) and has subsequently been identified in both muscle and nonmuscle cells from a variety of animals, in Acanthamoeba, and in Dictyostelium (Furukawa and Fechheimer, 1997;Critchley and Flood, 1999). ␣-Actinin forms a homodimer of antiparallel polypeptides (Critchley and Flood, 1999;Djinovic-Carugo et al., 1999), with the actin-binding domain of each polypeptide close to the NH 2 terminus, followed by four spectrin-like repeats and two COOH-terminal EF-hand motifs. Skeletal muscle isoforms are localized to the Z-disk and are not regulated by Ca 2ϩ , whereas nonmuscle isoforms are localized to focal adhesions, stress fibers, and other structures and are typically regulated by C...

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Section: Evolution and Functional Relationships Of Actinbundling Protmentioning

confidence: 99%

“…First, Ain1p was detected exclusively in this structure. Second, ain1 deletion cells display cell division defects under stress conditions, much as do cells lacking the nonessential myosin II Myp2p/Myo3p (Bezanilla et al, 1997;Motegi et al, 1997). Third, cells overexpressing Ain1p have defects in cell division.…”

Section: Roles Of Ain1p and Fim1p In Cytokinesismentioning

confidence: 99%

Roles of a Fimbrin and an α-Actinin-like Protein in Fission Yeast Cell Polarization and Cytokinesis

Bähler

Pringle

2001

MBoC

146

183

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“…It is not clear why S. pombe requires two class II myosins for cytokinesis. Myo2 is an essential gene whereas cells lacking Myp2 display only subtle cytokinetic defects that are exacerbated when cells are stressed [Bezanilla et al, 1997;Motegi et al, 1997;Mulvihill et al, 2000]. Combining myp2⌬ with the temperature-sensitive myo2 mutation myo2-E1 creates a double mutant that displays exaggerated cytokinetic de- Fig.…”

Section: It Takes Two: the Class II Myosinsmentioning

confidence: 99%

Take five: A myosin class act in fission yeast

Win¹,

Mulvihill²,

Hyams³

2002

Cell Motil. Cytoskeleton

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“…Fission yeast cells divide by means of a contractile actin ring (CAR) that both positions the cytokinetic septum and determines its structural and functional integrity (Marks and Hyams, 1985). The CAR contains two type II myosins encoded by the genes myo2ϩ May et al, 1997) and myp2ϩ/myo3ϩ (Bezanilla et al, 1997;Motegi et al, 1997). Myo2 is an essential component of the CAR May et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Myo2 is an essential component of the CAR May et al, 1997). Cytokinesis can proceed in the absence of Myp2 but less efficiently than when it is present (Bezanilla et al, 1997, Motegi et al, 1997, 2000Mulvihill et al, 2000). have claimed Myo2 assembles into the CAR in advance of Myp2, whereas Motegi et al (2000) conclude that the two myosins arrive at the division site coincidentally.…”

Section: Introductionmentioning

confidence: 99%

Localization of Fission Yeast Type II Myosin, Myo2, to the Cytokinetic Actin Ring Is Regulated by Phosphorylation of a C-Terminal Coiled-Coil Domain and Requires a Functional Septation Initiation Network

Mulvihill

Barretto

Hyams

2001

MBoC

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Myo2 truncations fused to green fluorescent protein (GFP) defined a C-terminal domain essential for the localization of Myo2 to the cytokinetic actin ring (CAR). The localization domain contained two predicted phosphorylation sites. Mutation of serine 1518 to alanine (S1518A) abolished Myo2 localization, whereas Myo2 with a glutamic acid at this position (S1518E) localized to the CAR. GFP-Myo2 formed rings in the septation initiation kinase (SIN) mutant cdc7-24 at 25°C but not at 36°C. GFP-Myo2S1518E rings persisted at 36°C incdc7-24 but not in another SIN kinase mutant,sid2-250. To further examine the relationship between Myo2 and the SIN pathway, the chromosomal copy ofmyo2 + was fused to GFP (strainmyo2-gc). Myo2 ring formation was abolished in the double mutants myo2-gc cdc7.24 and myo2-gc sid2-250 at the restrictive temperature. In contrast, activation of the SIN pathway in the double mutant myo2-gc cdc16-116 resulted in the formation of Myo2 rings which subsequently collapsed at 36°C. We conclude that the SIN pathway that controls septation in fission yeast also regulates Myo2 ring formation and contraction. Cdc7 and Sid2 are involved in ring formation, in the case of Cdc7 by phosphorylation of a single serine residue in the Myo2 tail. Other kinases and/or phosphatases may control ring contraction.

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Identification of Myo3, a second type‐II myosin heavy chain in the fission yeast Schizosaccharomyces pombe

Cited by 81 publications

References 22 publications

Roles of a Fimbrin and an α-Actinin-like Protein in Fission Yeast Cell Polarization and Cytokinesis

Roles of a Fimbrin and an α-Actinin-like Protein in Fission Yeast Cell Polarization and Cytokinesis

Take five: A myosin class act in fission yeast

Localization of Fission Yeast Type II Myosin, Myo2, to the Cytokinetic Actin Ring Is Regulated by Phosphorylation of a C-Terminal Coiled-Coil Domain and Requires a Functional Septation Initiation Network

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