meiotic telomere bouquet

cellstructuremech:meiotic_telomere_bouquet · Other · Nucleoprotein complex · Proposed

A polarized nuclear chromosome assembly in which telomeric ends and their anchoring proteins cluster within a restricted region of the nuclear envelope during meiotic prophase. Characterized in fission and budding yeast, it organizes chromosome ends while chromosome arms extend into the nucleus; its duration and tethering machinery differ between species. [DOI:10.1038/celldisc.2017.41]

Multipanel Figure 4: Rap1-GFP marks clustered chromosome ends in wild-type budding-yeast prophase I and dispersed ends in Mps2-depleted and csm4-deleted cells. Tub4-mApple marks the SPB; panel A bar is 1 micrometer. Bouquet frequency, viability and ARG4/HIS4 gene-conversion plots accompany the micrographs. OTHER · *Saccharomyces cerevisiae* (`NCBITaxon:4932`) · Jinbo Fan, Hui Jin, Bailey A Koch, Hong-Guo Yu; CC BY 4.0, via PubMed Central; unmodified Figure 4. · CC_BY_4_0 · source: PMC PMC7536833.1 fig4 · `DOI:10.26508/lsa.202000824`

Synonyms: telomere bouquet; chromosomal bouquet

Part of: nucleus (GO:0005634)

Has part: nuclear chromosome (GO:0000228); GO:0000781 — chromosome, telomeric region (no local record)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Grounding	Genes	Essential	Role
telomere	Dna	part of	`SO:0000624`		UNKNOWN	Ends of the linear nuclear chromosomes brought together at the nuclear periphery. `DOI:10.26508/lsa.202000824` Rap1-marked telomeres cluster at prophase I; the chromosome-end DNA is part of the assembly, not an external substrate. `DOI:10.1038/celldisc.2017.41` Taz1-marked chromosome ends remain associated with the SPB during the fission-yeast bouquet stage.
TE2IP/Rap1	Protein	part of	`InterPro:IPR039595`	RAP1, rap1	UNKNOWN	Telomere-associated scaffold class in both curated yeast systems. `DOI:10.26508/lsa.202000824` Rap1-GFP marks the budding-yeast bouquet. `DOI:10.1186/s12915-015-0149-x` Rap1-DD337AA retains telomeric localization but loses Bqt1/2 interaction and bouquet clustering.
Taz1-like telomere-binding protein	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	taz1	UNKNOWN	Fission-yeast chromosome-end DNA-binding constituent. `DOI:10.1038/celldisc.2017.41` Tagged Taz1 marks the clustered telomeres and their subsequent release.
Bqt1-like meiotic telomere connector	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	bqt1	UNKNOWN	Fission-yeast constituent of the Rap1-to-Sad1 bridge that maintains the bouquet. `DOI:10.1016/j.cell.2006.01.048` Readable primary abstract identifies the joint Bqt1/Bqt2 bridge between Rap1 and Sad1; full publisher text was not accessible. `DOI:10.1038/celldisc.2017.41` Direct live-cell and conditional-degradation experiments support bouquet residence and maintenance.
Bqt2-like meiotic telomere connector	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	bqt2	UNKNOWN	Partner of Bqt1 in the fission-yeast telomere-to-envelope bridge. `DOI:10.1016/j.cell.2006.01.048` Neither connector alone forms the reported bridge; this is not a whole-bouquet stoichiometry measurement. `DOI:10.1186/s12915-015-0149-x` Two-hybrid experiments assay Rap1 binding to a Bqt2-Bqt1 fusion and identify a separation-of-function Rap1 mutant.
SUN domain-containing protein 1-5	Protein	part of	`InterPro:IPR045119`	MPS3, sad1	UNKNOWN	Inner-nuclear-membrane tether class represented by budding-yeast Mps3 and fission-yeast Sad1. `DOI:10.26508/lsa.202000824` Mps3-Mps2 co-immunoprecipitation and localization dependencies support the budding-yeast tether. `DOI:10.1016/j.cell.2006.01.048` The directly reported Rap1-Bqt1/Bqt2-Sad1 bridge supports the fission-yeast example.
Monopolar spindle protein 2	Protein	part of	`InterPro:IPR031433`	MPS2	UNKNOWN	Budding-yeast outer-membrane linker joining telomere-associated Mps3 to Csm4. `DOI:10.26508/lsa.202000824` Mps2 colocalizes with Ndj1/Csm4 at chromosome ends; depletion disrupts Csm4 recruitment and bouquet formation.
Csm4-like meiotic telomere tether factor	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	CSM4	UNKNOWN	Budding-yeast telomere-associated membrane constituent required for normal clustering in the cited assay. `DOI:10.26508/lsa.202000824` Co-purification and chromosome spreads support physical association, not only a deletion phenotype. `DOI:10.1016/j.cub.2020.01.054` This study interprets Csm4 as an accessory regulator of the Mps2-Myo2 connection rather than the core SUN-KASH link.
Non-disjunction protein 1	Protein	part of	`InterPro:IPR062583`	NDJ1	UNKNOWN	Budding-yeast telomere-associated connector involved in membrane-tether recruitment. `DOI:10.26508/lsa.202000824` Ndj1 is required for Mps2 association with meiotic chromosome ends; ectopic reconstitution is distinguished from a normal meiotic bouquet.
Kms1-like nuclear-envelope tether protein	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	kms1	UNKNOWN	Outer-membrane constituent of the established fission-yeast Sad1-Kms1 bridge. `DOI:10.1038/s41467-025-56049-9` Sad1-Kms1 is the named LINC link in the fission-yeast telomere environment. The new recruitment experiment is explicitly in Rabl-deficient mitotic cells.

Organism-specific protein examples

Named proteins in which each component's role was established, with the organism the evidence comes from. The component above is the taxon-agnostic family; these are the specific entries behind it.

TE2IP/Rap1

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P11938`	DNA-binding protein RAP1	RAP1	Saccharomyces cerevisiae S288C (`NCBITaxon:559292`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.26508/lsa.202000824` Figure 4 uses Rap1-GFP at clustered meiotic chromosome ends. `https://www.uniprot.org/uniprotkb/P11938/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.
`UniProtKB:Q96TL7`	DNA-binding protein rap1	rap1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.1186/s12915-015-0149-x` Figure 4 directly images meiotic Rap1-YFP and compares a Bqt1/2-binding-defective mutant. `https://www.uniprot.org/uniprotkb/Q96TL7/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.

Taz1-like telomere-binding protein

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P79005`	Telomere length regulator taz1	taz1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.1038/celldisc.2017.41` Taz1-YFP tracks telomeres throughout live meiotic imaging. `https://www.uniprot.org/uniprotkb/P79005/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.

Bqt1-like meiotic telomere connector

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q92358`	Telomere bouquet protein 1	bqt1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.1038/celldisc.2017.41` Figure 7 follows tagged Bqt1; induced degradation releases telomeres from the SPB. `https://www.uniprot.org/uniprotkb/Q92358/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.

Bqt2-like meiotic telomere connector

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q9US52`	Telomere bouquet protein 2	bqt2	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.1016/j.cell.2006.01.048` Primary abstract directly identifies Bqt2 together with Bqt1 as the Rap1-Sad1 connector; no uninspected figure-level detail is inferred. `https://www.uniprot.org/uniprotkb/Q9US52/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.

SUN domain-containing protein 1-5

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P47069`	Spindle pole body assembly component MPS3	MPS3	Saccharomyces cerevisiae S288C (`NCBITaxon:559292`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.26508/lsa.202000824` Meiotic Mps3 localizes at chromosome ends; its depletion disrupts Mps2 telomere localization. `https://www.uniprot.org/uniprotkb/P47069/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.
`UniProtKB:Q09825`	Spindle pole body-associated protein sad1	sad1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.1016/j.cell.2006.01.048` The primary abstract identifies Sad1 as the envelope/SPB-side binding partner of the Bqt1/Bqt2 bridge. `https://www.uniprot.org/uniprotkb/Q09825/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.

Monopolar spindle protein 2

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P53159`	Monopolar spindle protein 2	MPS2	Saccharomyces cerevisiae S288C (`NCBITaxon:559292`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.26508/lsa.202000824` Figures 1-4 provide co-purification, telomere localization, recruitment dependency and bouquet-depletion evidence. `https://www.uniprot.org/uniprotkb/P53159/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.

Csm4-like meiotic telomere tether factor

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q08955`	Chromosome segregation in meiosis protein 4	CSM4	Saccharomyces cerevisiae S288C (`NCBITaxon:559292`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.26508/lsa.202000824` Csm4 colocalizes with Mps2 at chromosome ends; deletion abolishes normal bouquet formation. `https://www.uniprot.org/uniprotkb/Q08955/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.

Non-disjunction protein 1

Accession	Protein	Gene	Organism	Entry
`UniProtKB:Q12366`	Non-disjunction protein 1	NDJ1	Saccharomyces cerevisiae S288C (`NCBITaxon:559292`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.26508/lsa.202000824` Figure 3 colocalizes Ndj1 and Mps2 at chromosome ends and shows loss of Mps2 localization in ndj1 deletion. `https://www.uniprot.org/uniprotkb/Q12366/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.

Kms1-like nuclear-envelope tether protein

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P87245`	Karyogamy meiotic segregation protein 1	kms1	Schizosaccharomyces pombe 972h- (`NCBITaxon:284812`)	REVIEWED
Role and evidence (2 references) Reference-sequence exemplar, not a claim that the reference strain was the exact experimental stock. `DOI:10.1038/s41467-025-56049-9` The paper identifies Kms1 in the telomere-associated LINC system and directly follows its recruitment in a partial mitotic reconstitution, not a complete meiotic bouquet. `https://www.uniprot.org/uniprotkb/P87245/entry` Reviewed identity, native protein label, gene and source taxon verified. Structural role comes from the cited experiment.

Canonical examples

NCBITaxon:4932 Saccharomyces cerevisiae — Native meiotic assays use SK1-derived strains. The S288C mitotic reconstitution is not itself an ordinary meiotic bouquet; S288C UniProt entries serve only as sequence references. [DOI:10.26508/lsa.202000824]
NCBITaxon:4896 Schizosaccharomyces pombe — Live-cell meiotic prophase and conditional Bqt1-degradation experiments; bouquet persistence is distinguished from the period of horsetail movement. [DOI:10.1038/celldisc.2017.41]

Functions

telomere organization GO:0032200 — Polarized organization of chromosome ends during meiotic prophase.
- DOI:10.26508/lsa.202000824 Direct imaging of Rap1-marked peripheral clusters.
- DOI:10.1038/celldisc.2017.41 Taz1-marked telomeres remain clustered near the SPB during prophase.
Support of homolog pairing and meiotic recombination — The budding-yeast tether/bouquet system supports efficient homolog pairing and gene conversion, without making clustering alone the exclusive cause.
- DOI:10.26508/lsa.202000824 Mps2-depleted and csm4-deleted cells show delayed pairing at LYS4 and reduced gene conversion at ARG4/HIS4. Tethering, motion and clustering effects are not experimentally isolated from one another.
Support of meiotic spindle formation — Maintained fission-yeast telomere-SPB attachment supports normal SPB behavior and spindle formation.
- DOI:10.1038/celldisc.2017.41 Premature Bqt1 destruction increases spindle defects. Some bouquet-deficient cells still divide successfully, so no absolute requirement or universal fungal function is asserted.

Mechanism graphs

Budding-yeast tether recruitment and bouquet formation (ASSEMBLY)

Subject	Predicate	Object	Evidence
Ndj1-class connector	supports	Mps2 association with chromosome ends	`DOI:10.26508/lsa.202000824` Figure 3C; ndj1 deletion disrupts end-associated Mps2.
Mps3 SUN tether	supports	Mps2 association with chromosome ends	`DOI:10.26508/lsa.202000824` Figure 3C; Mps3 depletion disrupts Mps2 localization.
Mps2 linker	supports	Csm4 association with chromosome ends	`DOI:10.26508/lsa.202000824` Figure 3D; depletion removes end-associated Csm4 but preserves end-associated Mps3.
Mps2 linker	supports	Meiotic telomere clustering	`DOI:10.26508/lsa.202000824` Figure 4 compares wild type with meiosis-specific depletion; its separate SPB functions are not assigned to the bouquet.
Csm4 tether factor	supports	Meiotic telomere clustering	`DOI:10.26508/lsa.202000824` Figure 4; csm4 deletion disrupts normal clustering. This does not resolve the disputed structural boundary of the smaller t-LINC complex.
Meiotic telomere clustering	produces	Meiotic telomere bouquet	`DOI:10.26508/lsa.202000824` Live fluorescence identifies clustered Rap1-marked ends at prophase I.

Fission-yeast bouquet maintenance and meiotic spindle function (FUNCTION)

Subject	Predicate	Object	Evidence
Bqt1 connector	supports	Maintenance of the telomere-SPB connection	`DOI:10.1038/celldisc.2017.41` Conditional Bqt1-AID destruction during prophase releases telomeres, distinguishing maintenance from initial assembly.
Maintenance of the telomere-SPB connection	supports	Timely CDK1-cyclin B accumulation at the SPB	`DOI:10.1038/celldisc.2017.41` Live-cell Cdc2/Cdc13 localization and bqt1 deletion comparisons; the local molecular transfer mechanism remains unresolved.
Maintenance of the telomere-SPB connection	supports	Functional meiotic spindle formation	`DOI:10.1038/celldisc.2017.41` Auxin-dependent Bqt1 destruction yields defective SPBs and spindles; not all cells fail, and controls lacking the degron retain meiosis.

Discussions

CURATION_TODO (RESOLVED): Keep the chromosome assembly distinct from its formation process and tether subcomplexes.
CURATION_TODO (OPEN): Find exact whole-protein family identifiers for Taz1, Bqt1, Bqt2, Csm4 and Kms1.
KNOWLEDGE_GAP (OPEN): Resolve the core-versus-accessory placement of Csm4 within the smaller t-LINC complex.
CURATION_TODO (RESOLVED): Keep species-specific components and assembly requirements separate.
CURATION_TODO (RESOLVED): Distinguish telomere tethers from drivers, general envelope anchors and downstream machinery.
KNOWLEDGE_GAP (OPEN): Identify the physiological release mechanism without equating correlation with causation.
CURATION_TODO (RESOLVED): Avoid making clustering the unique cause of every mutant phenotype.
CURATION_TODO (RESOLVED): Preserve experimental taxon and measurement scope.
CURATION_TODO (RESOLVED): Identify which primary sources were read in full relevant sections and which were abstract-only.
CURATION_TODO (RESOLVED): Keep figure reuse permissions separate from data waivers and experimental panels.

More images

Figure 4 combines a Rap1 sequence alignment, asci, mitotic Rap1/Taz1 colocalization, and live meiotic time courses. Panel D compares wild type with Rap1-DD337AA mutants using Sid4-mCherry for the SPB, Rap1-YFP for telomeres and Hht1-Cerulean for chromatin; its bar is 2 micrometers. Panel C is mitotic, not a meiotic bouquet. OTHER · *Schizosaccharomyces pombe* (`NCBITaxon:4896`) · Hanna Amelina, Shaan Subramaniam, Vera Moiseeva, Christine Anne Armstrong, Siân Rosanna Pearson, Kazunori Tomita; CC BY 4.0, via PubMed Central; unmodified Figure 4. · CC_BY_4_0 · source: PMC PMC4660835.1 Fig4 · `DOI:10.1186/s12915-015-0149-x`

Datasets

Phosphorylation of S.pombe Rap1 analysed by LC-MS/MS (PXD001841) · PRIDE · PROTEOMICS
Organism: Schizosaccharomyces pombe · Platform: LC-MS/MS, LTQ Orbitrap Velos
Native PRIDE API identity, organism, experimental description and linked DOI/PMID verified on 2026-10-05. Partial submission; no raw spectra were downloaded or independently reanalyzed. A phosphorylation catalog is not proof that phosphorylation triggers bouquet dispersal.

Evidence

DOI:10.26508/lsa.202000824 Fan et al. 2020, PMID 32967926; native PMC7536833.1 Results, Discussion and relevant Methods read. Direct budding-yeast tether localization, co-purification, depletion, bouquet imaging and gene-conversion assays.
DOI:10.1186/s12915-015-0149-x Amelina et al. 2015, PMID 26058898; native PMC4660835.1 interaction/mutagenesis Results, Discussion, Methods and deposited dataset inspected.
DOI:10.1038/celldisc.2017.41 2017 study, PMID 29123917; native PMC5674143.1 bouquet-maintenance/function Results and Methods read. Live-cell and conditional-degradation evidence.
DOI:10.1016/j.cub.2020.01.054 2020 study, PMID 32059771; native PMC7181386.1 Results, Discussion and imaging/spread Methods read. Alternative Csm4 interpretation and motor-association evidence retained with limits.
DOI:10.1038/s41467-025-56049-9 2025 study, PMID 39833200; native PMC11747273.1 telocentrosome-recruitment and natural meiotic-entry Results read. Partial mitotic recruitment is distinct from complete bouquet formation.
DOI:10.1016/j.cell.2006.01.048 Chikashige et al. 2006, PMID 16615890; DOI/PMID and complete abstract read via Europe PMC. Publisher access returned 403; Europe PMC lists subscription-only access. Connector claims are limited to the abstract, corroborated by later studies.
GO:0032993 Native protein-DNA complex definition is broader than this named assembly.
GO:0005634 Native nucleus definition verifies the encompassing compartment.
GO:0000228 Native nuclear chromosome definition; chromosomes participate in the polarized assembly.
GO:0000781 — chromosome, telomeric region Native chromosome, telomeric region definition denotes the grouped ends, not the whole bouquet.

Curation history

2026-10-05T18:42:59Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-05T18:46:29Z codex · EXPANDED_RECORD — Added ten component classes, eleven verified protein examples, two species-scoped mechanisms, a verified proteomics dataset, two inspected CC BY figures, and explicit model and access limits.

Source: data/structures/other/meiotic_telomere_bouquet.yaml