Fta2, an Essential Fission Yeast Kinetochore Component, Interacts Closely with the Conserved Mal2 Protein

Kerres, Anne; Jakopec, Visnja; Beuter, Christoph; Karig, Inga; Pöhlmann, Jennifer; Pidoux, Alison L.; Allshire, Robin C.; Fleig, Ursula

doi:10.1091/mbc.e06-04-0264

Cited by 18 publications

(28 citation statements)

References 48 publications

(101 reference statements)

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“…To determine how chromosome retrieval is achieved we filmed ⌬mto1 fta2-tdTomato nmt1-gfp-atb2 cells during mitosis. Fta2 is a constitutively bound component of the fission yeast kinetochore (Liu et al, 2005;Kerres et al, 2006). In all the ⌬mto1 fta2-tdTomato nmt1-gfp-atb2 cells examined we found that unclustered kinetochores were retrieved (20/20 movies), indicating that mild overexpression of atb2 from the nmt1 promoter does not effect the retrieval process.…”

Section: Resultsmentioning

confidence: 81%

The Dam1/DASH complex is required for the retrieval of unclustered kinetochores in fission yeast

Franco¹,

Meadows²,

Millar

2007

Journal of Cell Science

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In fission yeast centromeres cluster at the nuclear envelope in a region underlying the spindle pole body during interphase, an arrangement known as a Rabl configuration. We have identified a strain in which one pair of sister kinetochores is unclustered from the others and binds the nuclear envelope at a point distal to the spindle pole body. We show that during mitosis unclustered kinetochores are captured by intranuclear spindle microtubules which then pull the kinetochores back to one of the two spindle poles before they are bi-oriented on the mitotic spindle. We find that kinetochore retrieval occurs at the depolymerising microtubule plus end and is dependent on the non-essential Dam1/DASH complex. In the absence of Dam1 unclustered kinetochores are captured on the lateral surface of spindle microtubule bundles but poleward kinetochore movement does not occur. These data provide the first direct evidence that the Dam1/DASH complex can couple the force generated by microtubule depolymerisation to direct chromosome movement in vivo.

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Section: Resultsmentioning

confidence: 81%

The Dam1/DASH complex is required for the retrieval of unclustered kinetochores in fission yeast

Franco¹,

Meadows²,

Millar

2007

Journal of Cell Science

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“…We had proposed previously that the Spc7 protein plays a direct role at the microtubule-kinetochore interface as Spc7 was identified as a suppressor of the EB1 family member Mal3 and interacted with this protein genetically as well as physically (Kerres et al, 2004). Very recently the Spc7 ortholog from C. elegans, the KNL-1 protein, has been shown to have a specific microtubule-binding activity, suggesting that this protein family is part of the core microtubule-binding site of the kinetochore .In this work, we have extended our analysis of Spc7 function and have shown 1) Spc7 is required for formation/ function of the spindle in vivo, 2) Spc7 is required for kinetochore association of the MIND complex, and 3) Spc7 provides a genetic link between the two S. pombe kinetochore complexes Sim4 and Ndc80-MIND-Spc7 as it is required for kinetochore targeting of the Sim4 complex component Fta2 and extra expression of the Sim4 complex component Mal2 rescues the spc7 mutant phenotypes (Kerres et al, 2006). Extra Spc7 can partially rescue the temperature sensitivity of the mis12 and mis14 mutant strains ( Supplementary Figure 1; Obuse et al, 2004).…”

mentioning

confidence: 75%

The Conserved Spc7 Protein Is Required for Spindle Integrity and Links Kinetochore Complexes in Fission Yeast

Kerres

Jakopec

Fleig

2007

MBoC

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Spc7, a member of the conserved Spc105/KNL-1 family of kinetochore proteins, was identified as an interaction partner of the EB1 homologue Mal3. Spc7 associates with the central centromere region of the chromosome but does not affect transcriptional silencing. Here, we show that Spc7 is required for the integrity of the spindle as well as for targeting of MIND but not of Ndc80 complex components to the kinetochore. Spindle defects in spc7 mutants were severe ranging from the inability to form a bipolar spindle in early mitosis to broken spindles in midanaphase B. spc7 mutant phenotypes were partially rescued by extra alpha-tubulin or extra Mal2. Thus, Spc7 interacts genetically with the Mal2-containing Sim4 complex.

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“…Synthetic lethality of double mutant strains was scored by analyzing at least 12 tetrads of the relevant cross. S. pombe and Schizosaccharomyces japonicus (25). In this screen, 102 of 370,000 transformants were able to grow at the restrictive temperature.…”

Section: Methodsmentioning

confidence: 96%

“…Tetrad analysis of 75 heterozygous ⌬sos7/sos7 ϩ diploids revealed that only the 2 his Ϫ spores/tetrad grew. sos7 ts variants replaced the endogenous sos7 ϩ in strain KG425: transformants unable to grow at 36°C were backcrossed twice and sequenced as described previously (25). sos7 and spc7 plasmidexpressed variants were generated via PCR and cloning of the resulting DNA fragments into pJR2 vectors with the nmt1 ϩ promoter (41).…”

Section: Methodsmentioning

confidence: 99%

“…The 13-component Sim4-Mal2-Mis6 kinetochore complex was isolated separately from the Ndc80-MIND-Spc7 complex, although interactions exist between these two complexes (25)(26)(27)37). We analyzed whether overexpression of sos7 ϩ rescued the nongrowth phenotype of the mis6-302, mis15 -68, mis17-362, sim4-193, fta2-291, and mal2-1 Sim4-Mal2-Mis6 complex mutants and found that this was not the case (unpublished observations) (12,21,25,52,66). Sos7-GFP was localized correctly in all of these Sim4-Mal2-Mis6 complex mutant strains grown at the restrictive temperatures, although kinetochore association was reduced moderately in the mal2-1 and fta2-291 strains (see Fig.…”

Section: Region Shows Autoactivation (Unpublished Observations)mentioning

confidence: 99%

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Sos7, an Essential Component of the Conserved Schizosaccharomyces pombe Ndc80-MIND-Spc7 Complex, Identifies a New Family of Fungal Kinetochore Proteins

Jakopec

Topolski

Fleig

2012

Molecular and Cellular Biology

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Chromosome segregation is powered by the kinetochore, a large macromolecular structure assembled on centromeric chromatin. Attachment of sister chromatids to microtubules is mediated by the highly conserved tripartite KMN (acronym for KNL-1-Mis12-Ndc80) kinetochore network. In the fission yeast Schizosaccharomyces pombe, the equivalent complex is called NMS (Ndc80-MIND-Spc7). Here, we show that not all components of the NMS complex had been identified previously. A 10th NMS component exists, the essential Sos7 protein, which is a genetic and physical interaction partner of Spc7. The analysis of sos7 kinetochore-null mutant yeast strains demonstrated that Sos7 is central to NMS function. In particular, Sos7 is required for kinetochore targeting of Spc7 as well as components of the MIND complex. sos7 mutant strains show severe chromosome missegregation phenotypes and have compromised microtubule-kinetochore interactions. Sos7 is the founding member of a functionally conserved fungal kinetochore family not present in the point centromere carrying Saccharomycotina clusters, suggesting that the new Sos7 family might be a signature motif of fungi with regional centromeres.T he faithful transmission of eukaryotic chromosomes to the progeny is a complex process that requires coordinated protein interactions at the kinetochore-microtubule interface. The erosion of chromosome segregation fidelity leading to the loss/gain of chromosomes is of great medical relevance, as aneuploidy has been implicated to have a causative role in a number of diseases (1,38,68). The proper partitioning of sister chromatids in mitotis is mediated via direct contact of spindle microtubules with components of the outer kinetochore. Kinetochores are macromolecular structures assembled on the chromosomal centromere region. Apart from providing mechanical attachment sites, these organelles generate the spindle checkpoint signaling that ascertains proper sister chromatid biorientation before anaphase onset (44). Although kinetochores are very complex structures and the number of kinetochore proteins identified is still increasing, the direct interaction with spindle fibers is mediated largely by a highly conserved protein network called the KMN complex in higher eucaryotes and the NMS complex in the fission yeast Schizosaccharomyces pombe (2, 37, 47). The KMN-NMS network is composed of 3 subcomplexes: the Ndc80 complex and the MINDMis12 complex, each comprising 4 components, and a protein called KNL-1 in Caenorhabditis elegans, Blinkin-hSpc105 in vertebrates, Spc105 in Saccharomyces cerevisiae and Drosophila, and Spc7 in S. pombe (59,67,74). In addition, budding yeast Spc105 forms a subcomplex with the Kre28 protein, Blinkin binds metazoan Zwint via its C-terminal end, and KNL-1 interacts with 29,30,[46][47][48]. The mitotic functions of Kre28 and KBP-5 have yet to be analyzed, whereas the Zwint protein is required for kinetochore residency of the mitotic checkpoint relevant RZZ (Rod-Zw10-Zwilch) complex (10,65,70). It has been suggested that Kre28 ...

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Fta2, an Essential Fission Yeast Kinetochore Component, Interacts Closely with the Conserved Mal2 Protein

Cited by 18 publications

References 48 publications

The Dam1/DASH complex is required for the retrieval of unclustered kinetochores in fission yeast

The Dam1/DASH complex is required for the retrieval of unclustered kinetochores in fission yeast

The Conserved Spc7 Protein Is Required for Spindle Integrity and Links Kinetochore Complexes in Fission Yeast

Sos7, an Essential Component of the Conserved Schizosaccharomyces pombe Ndc80-MIND-Spc7 Complex, Identifies a New Family of Fungal Kinetochore Proteins

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