Download MendeleyStructural basis of meiotic chromosome synaptic elongation through hierarchical fibrous assembly of SYCE2-TEX12.
Dunce, J.M., Salmon, L.J., Davies, O.R.(2021) Nat Struct Mol Biol 28: 681-693
- PubMed: 34373646
- DOI: https://doi.org/10.1038/s41594-021-00636-z
- Primary Citation of Related Structures:
6R17, 6YQF - PubMed Abstract:
The synaptonemal complex (SC) is a supramolecular protein assembly that mediates synapsis between homologous chromosomes during meiosis. SC elongation along the chromosome length (up to 24 μm) depends on its midline α-fibrous component SYCE2-TEX12. Here, we report X-ray crystal structures of human SYCE2-TEX12 as an individual building block and on assembly within a fibrous lattice. We combine these structures with mutagenesis, biophysics and electron microscopy to reveal the hierarchical mechanism of SYCE2-TEX12 fiber assembly. SYCE2-TEX12's building blocks are 2:2 coiled coils that dimerize into 4:4 hetero-oligomers and interact end-to-end and laterally to form 10-nm fibers that intertwine within 40-nm bundled micrometer-long fibers that define the SC's midline structure. This assembly mechanism bears striking resemblance with intermediate filament proteins vimentin, lamin and keratin. Thus, SYCE2-TEX12 exhibits behavior typical of cytoskeletal proteins to provide an α-fibrous SC backbone that structurally underpins synaptic elongation along meiotic chromosomes.
Organizational Affiliation:
Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle upon Tyne, UK.
