Myosin genes in <i>Tetrahymena</i>

Williams, Selwyn A.; Gavin, R. H.

doi:10.1002/cm.20078

Cited by 24 publications

(28 citation statements)

References 27 publications

(29 reference statements)

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“…2 and Table 2). That this robust association had not been recognized previously (4,19,25,26), with the ciliate myosins recently having been assigned to a separate class (19), is most likely because of the inclusion of rogue sequences, small dataset size, and the use of full-length myosin sequences in previous analyses. Based on our strong statistical support for this extended class XIV and on independent corroborating evidence (see below), we now include these 12 ciliate myosins in class XIV as subclass XIVd (Fig.…”

Section: Resultsmentioning

confidence: 80%

“…In contrast, the frequent clustering of class XII with other divergent myosins [like those of classes III, XVI, XVII, XVIII, and͞or XX; see Fig. 1 (4,5,19)] is probably artifactual because of long-branch attraction, a notion supported by the increase of median statistical support for a monophyletic class XII͞XV grouping from 74% to 87% (BS) and from 0 to 0.99 (PP) when class XX myosins (in addition to other rogue sequences) are excluded from the analysis (small dataset; see Table 2). For further details on the likely monophyly of classes XII and XV, see Supporting Text.…”

Section: Resultsmentioning

confidence: 99%

“…2 and Table 1). TtMyo1 has been shown to be involved in phagosome motility and nuclear elongation (29,30), and the other T. thermophila myosins have been described elsewhere (19); one of them (TtMyo13) remains unclassified (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

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New insights into myosin evolution and classification

Foth

Goedecke

Soldati

2006

Proc. Natl. Acad. Sci. U.S.A.

435

436

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Myosins are eukaryotic actin-dependent molecular motors important for a broad range of functions like muscle contraction, vision, hearing, cell motility, and host cell invasion of apicomplexan parasites. Myosin heavy chains consist of distinct head, neck, and tail domains and have previously been categorized into 18 different classes based on phylogenetic analysis of their conserved heads. Here we describe a comprehensive phylogenetic examination of many previously unclassified myosins, with particular emphasis on sequences from apicomplexan and other chromalveolate protists including the model organism Toxoplasma, the malaria parasite Plasmodium, and the ciliate Tetrahymena. Using different phylogenetic inference methods and taking protein domain architectures, specific amino acid polymorphisms, and organismal distribution into account, we demonstrate a hitherto unrecognized common origin for ciliate and apicomplexan class XIV myosins. Our data also suggest common origins for some apicomplexan myosins and class VI, for classes II and XVIII, for classes XII and XV, and for some microsporidian myosins and class V, thereby reconciling evolutionary history and myosin structure in several cases and corroborating the common coevolution of myosin head, neck, and tail domains. Six novel myosin classes are established to accommodate sequences from chordate metazoans (class XIX), insects (class XX), kinetoplastids (class XXI), and apicomplexans and diatom algae (classes XXII, XXIII, and XXIV). These myosin (sub)-classes include sequences with protein domains (FYVE, WW, UBA, ATS1-like, and WD40) previously unknown to be associated with myosin motors. Regarding the apicomplexan ''myosome,'' we significantly update class XIV classification, propose a systematic naming convention, and discuss possible functions in these parasites.Apicomplexa ͉ Chromalveolata

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Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

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New insights into myosin evolution and classification

Foth

Goedecke

Soldati

2006

Proc. Natl. Acad. Sci. U.S.A.

435

436

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“…Members of this 'MyTH-FERM' superclass of myosins are expressed in organisms ranging from slime molds to humans (Breshears et al, 2010). Because the ciliate Tetrahymena thermophila also expresses myosins that contain MyTH4-FERM domains (Sugita et al, 2011;Williams and Gavin, 2005), myosins with these domains either arose very early in eukaryotic evolution or independently in two different lineages. Importantly, studies in Dictyostelium discoideum indicate that MyTH-FERM myosins have ancient and conserved roles in mediating membrane-cytoskeleton interactions in protrusive structures such as filopodia (Tuxworth et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Myosin-X: a MyTH-FERM myosin at the tips of filopodia

Kerber

Cheney

2011

Journal of Cell Science

135

131

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SummaryMyosin-X (Myo10) is an unconventional myosin with MyTH4-FERM domains that is best known for its striking localization to the tips of filopodia and its ability to induce filopodia. Although the head domain of Myo10 enables it to function as an actin-based motor, its tail contains binding sites for several molecules with central roles in cell biology, including phosphatidylinositol (3,4,5)-trisphosphate, microtubules and integrins. Myo10 also undergoes fascinating long-range movements within filopodia, which appear to represent a newly recognized system of transport. Myo10 is also unusual in that it is a myosin with important roles in the spindle, a microtubulebased structure. Exciting new studies have begun to reveal the structure and single-molecule properties of this intriguing myosin, as well as its mechanisms of regulation and induction of filopodia. At the cellular and organismal level, growing evidence demonstrates that Myo10 has crucial functions in numerous processes ranging from invadopodia formation to cell migration.

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“…Myo1 is one of 13 myosins in Tetrahymena thermophila and the founding myosin in ciliates (Garcés and Gavin, 1998;Williams and Gavin, 2005). This myosin and eleven other myosins in T. thermophila were initially assigned to Class XX in the myosin superfamily , but reassigned to a subclass within Class XIV in another phylogenetic analysis (Foth et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

MY01, a class XIV myosin, affects developmentally‐regulated elimination of the macronucleus during conjugation of Tetrahymena thermophila

Garcés

Hosein

Gavin

2009

Biology of the Cell

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Background information. Nuclear dimorphism is characteristic of ciliated protozoa. A transcriptionally-active macronucleus co-exists with a transcriptionally-silent micronucleus, which is activated only at conjugation. During conjugation, each conjugant develops two new genetically matched macronuclei and micronuclei, and the pre-existing macronucleus is eliminated. Elimination of the pre-existing macronucleus during conjugation is an apoptotic-like process. The macronucleus becomes highly condensed, DNA laddering occurs, caspase activity increases, acidic enzymes accumulate within the nucleoplasm, and the nucleus shrinks in size. The current study focused on the involvement of actin and myosin in nuclear events of conjugation. A myosin knockout strain was mated with wild-type, and the nuclear events were monitored with confocal microscopy.Results. Early nuclear events, including development of new macronuclei and micronuclei, appeared qualitatively normal in knockout conjugants. Completion of nuclear condensation and acidification in the pre-existing macronucleus was blocked in 44% of knockout conjugants. Knockout conjugants that failed to fully achieve nuclear condensation and acidification did not eliminate the pre-existing macronucleus. In control experiments, blockage of chromatin condensation, nuclear acidification, and macronuclear elimination was never observed in wild-type conjugants.Conclusions. Perturbation of either DNA fragmentation, chromatin condensation or nuclear acidification can lead to blockage of apoptotic-like elimination of the macronucleus in MYO1-knockout conjugants. Consistent with the known motor function of myosins and the involvement of Myo1 in vesicle trafficking in Tetrahymena, we argue that Myo1 could specifically affect condensation of chromatin and acidification of the nucleus through direct interaction with chromatin and through Myo1-dependent vesicle trafficking to the nucleus.

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Myosin genes in Tetrahymena

Abstract: This report presents an initial comparison of motor, neck, and tail domains of myosin genes in Tetrahymena thermophila. An unrooted phylogenetic tree drawn from alignment of predicted amino acid translations determined the relationship among

Cited by 24 publications

References 27 publications

New insights into myosin evolution and classification

New insights into myosin evolution and classification

Myosin-X: a MyTH-FERM myosin at the tips of filopodia

MY01, a class XIV myosin, affects developmentally‐regulated elimination of the macronucleus during conjugation of Tetrahymena thermophila

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