Microtubule nucleation by γ-tubulin-containing rings in the centrosome

Moritz, Michelle; Braunfeld, Michael B.; Sedat, John W.; Alberts, Bruce; Agard, David A.

doi:10.1038/378638a0

Cited by 506 publications

(373 citation statements)

References 11 publications

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“…Candidate proteins for homology studies include 50 kDa proteins ␣-and ␤-tubulin, which comprise the heterodimers of microtubules, and all others listed in Table 1. Studies might seek, for example, homologies with ␥-tubulin, which forms rings 25 nm in diameter that are capable of nucleating microtubule assembly, possibly by the transient stabilization of the minus-end (Moritz et al, 1995). This protein, which is sensitive to the mitotic stage, increases in concentration during prophase (Khodjakov and Rieder, 1999).…”

Section: Motility Proteins and The Search For Bacterial Homologuesmentioning

confidence: 99%

Motility proteins and the origin of the nucleus

et al. 2002

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Hypotheses on the origin of eukaryotic cells must account for the origin of the microtubular cytoskeletal structures (including the mitotic spindle, undulipodium/cilium (so-called flagellum) and other structures underlain by the 9(2)ϩ2 microtubular axoneme) in addition to the membrane-bounded nucleus. Whereas bacteria with membrane-bounded nucleoids have been described, no precedent for mitotic, cytoskeletal, or axonemal microtubular structures are known in prokaryotes. Molecular phylogenetic analyses indicate that the cells of the earliest-branching lineages of eukaryotes contain the karyomastigont cytoskeletal system. These protist cells divide via an extranuclear spindle and a persistent nuclear membrane. We suggest that this association between the centriole/kinetosome axoneme (undulipodium) and the nucleus existed from the earliest stage of eukaryotic cell evolution. We interpret the karyomastigont to be a legacy of the symbiosis between thermoacidophilic archaebacteria and motile eubacteria from which the first eukaryote evolved. Mutually inconsistent hypotheses for the origin of the nucleus are reviewed and sequenced proteins of cell motility are discussed because of their potential value in resolving this problem. A correlation of fossil evidence with modern cell and microbiological studies leads us to the karyomastigont theory of the origin of the nucleus. Anat Rec 268: 290 -301, 2002.

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Section: Motility Proteins and The Search For Bacterial Homologuesmentioning

confidence: 99%

Motility proteins and the origin of the nucleus

et al. 2002

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“…Recently however, electron microscopy tomography and high-resolution fluorescence microscopy of centrosomes from Drosophila, Spisula and mammalian cells have identified ring-like structures and protein complexes of higher order (Dictenberg et al 1998;Moritz et al 1995a;Vogel et al 1997). These ring-like structures colocalize with gamma-tubulin, a conserved centrosomal component, in immunoelectron microscopy (Moritz et al 1995b) suggesting them to be akin to the c-tubulin ring complex (cTuRC) involved in microtubule nucleation.…”

Section: Introductionmentioning

confidence: 99%

Structure and microtubule-nucleation activity of isolated Drosophila embryo centrosomes characterized by whole mount scanning and transmission electron microscopy

Lange

Kirfel

Gestmann

et al. 2005

Histochem Cell Biol

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Experimental approaches in Drosophila melanogaster over the last 20 years have played a fundamental role in elucidating the function, structure and molecular composition of the centrosome. However, quantitative data on the structure and function of the Drosophila centrosome are still lacking. This study uses, for the first time, whole mount electron microscopy in combination with negative staining on isolated centrosomes from the early Drosophila embryos to analyze its dimensions, structure and capacity to nucleate microtubules in vitro. We show that these organelles are on average 0.75 lm in diameter and have abundant pericentriolar material which often appears fibrillar and with bulbous protrusions. Corresponding to the abundant pericentriolar material, extensive microtubule nucleation occurs. Quantification of the number of microtubules nucleated showed that 50-300 active nucleation sites are present. We examined via electron microscopy immunogold labeling the distribution of c-tubulin, CNN, Asp and the MPM-2 epitopes that are phosphorylated through Polo and the Cdk1 kinase. The distribution of these proteins is homogeneous, with the MPM-2 epitopes exhibiting the highest density. In contrast, centrosomal subdomains are identified using a centriole marker to relate centrosome size to the centriole number by electron microscopy. In conclusion, we present a clear-cut technique assaying and quantifying the microtubule nucleation capacity and antigen distribution complementing molecular studies on centrosome protein complexes, cell organelle assembly and protein composition.

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“…␥TuRCs from these organisms share a similar structure and protein composition, and they can nucleate MTs in vitro (Zheng et al, 1995;Oegema et al, 1999;Murphy et al, 2001). Additional biochemical and structural studies reveal that ␥TuRC is recruited to the centrosome to mediate MT nucleation (Moritz et al, 1995a(Moritz et al, , 1995bMartin et al, 1998;Schnackenberg et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Characterization of a New γTuRC Subunit with WD Repeats

Gunawardane

Martin

Zheng

2003

MBoC

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The ␥-tubulin ring complex (␥TuRC), consisting of multiple protein subunits, can nucleate microtubule assembly. Although many subunits of the ␥TuRC have been identified, a complete set remains to be defined in any organism. In addition, how the subunits interact with each other to assemble into ␥TuRC remains largely unknown. Here, we report the characterization of a novel ␥TuRC subunit, Drosophila gamma ring protein with WD repeats (Dgp71WD). With the exception of ␥-tubulin, Dgp71WD is the only ␥TuRC component identified to date that does not contain the grip motifs, which are signature sequences conserved in ␥TuRC components. By performing immunoprecipitations after pair-wise coexpression in Sf9 cells, we show that Dgp71WD directly interacts with the grip motif-containing ␥TuRC subunits, Dgrips84, 91, 128, and 163, suggesting that Dgp71WD may play a scaffolding role in ␥TuRC organization. We also show that Dgrips128 and 163, like Dgrips84 and 91, can interact directly with ␥-tubulin. Coexpression of any of these grip motif-containing proteins with ␥-tubulin promotes ␥-tubulin binding to guanine nucleotide. In contrast, in the same assay Dgp71WD interacts with ␥-tubulin but does not facilitate nucleotide binding.

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Microtubule nucleation by γ-tubulin-containing rings in the centrosome

Cited by 506 publications

References 11 publications

Motility proteins and the origin of the nucleus

Motility proteins and the origin of the nucleus

Structure and microtubule-nucleation activity of isolated Drosophila embryo centrosomes characterized by whole mount scanning and transmission electron microscopy

Characterization of a New γTuRC Subunit with WD Repeats

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