Regulation and function of the fission yeast myosins

East, Daniel A.; Mulvihill, Daniel P.

doi:10.1242/jcs.078527

Cited by 13 publications

(12 citation statements)

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“…Myp2 began to accumulate in fully formed contractile rings at time +20 min (Figures 1A asterisk and 1B) [25]. Myo52 transports cargo including vesicles with Bgs1 β-1,3-glucan synthase along actin filament cables during interphase and mitosis, but does not concentrate in the contractile ring [14, 23, 24, 31–33]. We confirmed previous observations [32, 33] that the Δ myo52 strain grows slowly at both 25°C and 36°C, that the Δ myo52 mutation did not enhance the myo2-E1 growth defect at either temperature, but that Δ myo52 is synthetically lethal with Δ myp2 at 36°C (Figure S1A).…”

Section: Resultsmentioning

confidence: 99%

“…Fission yeast cells are favorable for investigating cytokinesis motors, since a large body of quantitative information is available on its division (for a review see [13]), and the genome encodes just five myosin heavy chains: type I myosin myo1 + ; type II myosins myo2 + and myp2 + ; and type V myosins myo51 + and myo52 + [14]. Myosin molecules consist of heavy chains and light chains, and we refer to each molecule in this work by the name of its heavy chain (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Myp2p is not essential for viability or cytokinesis under normal growth conditions [19, 21, 22] and is unconventional, since its exceptionally long tail folds upon itself to form an anti-parallel coiled-coil [21]. Myo51 and Myo52 carry cargo along actin filament cables, a crucial contribution to cell polarity [14]. During cell division Myo51 redistributes from actin cables to the equator [23], and Myo52 transports vesicles containing beta-glucan synthetase Bgs1 along actin cables to the forming septum (but does not concentrate in the contractile ring) [24].…”

Section: Introductionmentioning

confidence: 99%

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Three Myosins Contribute Uniquely to the Assembly and Constriction of the Fission Yeast Cytokinetic Contractile Ring

et al. 2015

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Summary Cytokinesis in fission yeast cells depends on conventional myosin-II (Myo2) to assemble and constrict a contractile ring of actin filaments. Less is known about the functions of an unconventional myosin-II (Myp2) and a myosin-V (Myo51) that are also present in the contractile ring. Myo2 appears in cytokinetic nodes around the equator 10 min before spindle pole body separation (cell cycle time −10 min) independent of actin filaments, followed by Myo51 at time zero and Myp2 at time +20 min, both located between nodes and dependent on actin filaments. We investigated the contributions of these three myosins to cytokinesis using a severely disabled mutation of the essential myosin-II heavy chain gene (myo2-E1) and deletion mutations of the other myosin heavy chain genes. Cells with only Myo2 assemble contractile rings normally. Cells with either Myp2 or Myo51 alone can assemble nodes and actin filaments into contractile rings, but complete assembly later than normal. Both Myp2 and Myo2 contribute to constriction of fully assembled rings at rates 55% of normal in cells relying on Myp2 alone and 25% of normal in cells with Myo2 alone. Myo51 alone cannot constrict rings but increases the constriction rate by Myo2 in Δmyp2 cells or Myp2 in myo2-E1 cells. Three myosins function in a hierarchal, complementary manner to accomplish cytokinesis with Myo2 and Myo51 taking the lead during contractile ring assembly and Myp2 making the greatest contribution to constriction.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Three Myosins Contribute Uniquely to the Assembly and Constriction of the Fission Yeast Cytokinetic Contractile Ring

et al. 2015

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“…Interestingly, myosin II is the major motor protein involved in actomyosin contraction in metazoan muscle and nonmuscle cells (Clark et al 2007), providing contractile force during cytokinesis in the latter (Matsumura 2005), a function also performed by members of yeast myosin class II (East and Mulvihill 2011). Metazoans have two subclasses of myosin II, referred to here as smooth (Myo2) and striated (Myo11/zipper) muscle myosins (fig.…”

Section: Resultsmentioning

confidence: 99%

Evolution and Classification of Myosins, a Paneukaryotic Whole-Genome Approach

Sebé-Pedrós¹,

Grau‐Bové²,

Richards³

et al. 2014

Genome Biology and Evolution

133

127

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Myosins are key components of the eukaryotic cytoskeleton, providing motility for a broad diversity of cargoes. Therefore, understanding the origin and evolutionary history of myosin classes is crucial to address the evolution of eukaryote cell biology. Here, we revise the classification of myosins using an updated taxon sampling that includes newly or recently sequenced genomes and transcriptomes from key taxa. We performed a survey of eukaryotic genomes and phylogenetic analyses of the myosin gene family, reconstructing the myosin toolkit at different key nodes in the eukaryotic tree of life. We also identified the phylogenetic distribution of myosin diversity in terms of number of genes, associated protein domains and number of classes in each taxa. Our analyses show that new classes (i.e., paralogs) and domain architectures were continuously generated throughout eukaryote evolution, with a significant expansion of myosin abundance and domain architectural diversity at the stem of Holozoa, predating the origin of animal multicellularity. Indeed, single-celled holozoans have the most complex myosin complement among eukaryotes, with paralogs of most myosins previously considered animal specific. We recover a dynamic evolutionary history, with several lineage-specific expansions (e.g., the myosin III-like gene family diversification in choanoflagellates), convergence in protein domain architectures (e.g., fungal and animal chitin synthase myosins), and important secondary losses. Overall, our evolutionary scheme demonstrates that the ancestral eukaryote likely had a complex myosin repertoire that included six genes with different protein domain architectures. Finally, we provide an integrative and robust classification, useful for future genomic and functional studies on this crucial eukaryotic gene family.

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“…By contrast, Cdc8p is absent from the Arp2/3‐mediated branched actin utilized in endocytic patches (Balasubramanian et al, ; Kovar et al, ). Each of the three fission yeast actin structures associate with different myosins (East and Mulvihill, ; Kovar et al, ), and previous work with Cdc8p highlighted a role for tropomyosin in the regulation of these actin‐based motors. As opposed to limiting access to the actin track as in muscle (Lehrer, ), decoration of actin with Cdc8p positively regulates myosin‐II (Myo2p) activity and function at contractile rings (Stark et al, ).…”

Section: Introductionmentioning

confidence: 97%

Myosin motor isoforms direct specification of actomyosin function by tropomyosins

et al. 2015

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Myosins and tropomyosins represent two cytoskeletal proteins that often work together with actin filaments in contractile and motile cellular processes. While the specialized role of tropomyosin in striated muscle myosin-II regulation is well characterized, its role in non-muscle myosin regulation is poorly understood. We previously showed that fission yeast tropomyosin (Cdc8p) positively regulates myosin-II (Myo2p) and myosin-V (Myo52p) motors. To understand the broader implications of this regulation we examined the role of two mammalian tropomyosins (Tpm3.1cy/Tm5NM1 and Tpm4.2cy/Tm4) recently implicated in cancer cell proliferation and metastasis. Like Cdc8p, the Tpm3.1cy and Tpm4.2cy isoforms significantly enhance Myo2p and Myo52p motor activity, converting non-processive Myo52p molecules into processive motors that can walk along actin tracks as single molecules. In contrast to the positive regulation of Myo2p and Myo52p, Cdc8p and the mammalian tropomyosins potently inhibited skeletal muscle myosin-II, while having negligible effects on the highly processive mammalian myosin-Va. In support of a conserved role for certain tropomyosins in regulating non-muscle actomyosin structures, Tpm3.1cy supported normal contractile ring function in fission yeast. Our work reveals that actomyosin regulation by tropomyosin is dependent on the myosin isoform, highlighting a general role for specific isoforms of tropomyosin in sorting myosin motor outputs.

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Regulation and function of the fission yeast myosins

Cited by 13 publications

References 96 publications

Three Myosins Contribute Uniquely to the Assembly and Constriction of the Fission Yeast Cytokinetic Contractile Ring

Three Myosins Contribute Uniquely to the Assembly and Constriction of the Fission Yeast Cytokinetic Contractile Ring

Evolution and Classification of Myosins, a Paneukaryotic Whole-Genome Approach

Myosin motor isoforms direct specification of actomyosin function by tropomyosins

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