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Structural basis of meiotic chromosome synaptic elongation through hierarchical fibrous assembly of SYCE2-TEX12

DOI: 10.1038/s41594-021-00636-z DOI Help

Authors: James M. Dunce (University of Cambridge; Newcastle University) , Lucy J. Salmon (Newcastle University) , Owen R. Davies (Newcastle University; University of Edinburgh)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Structural & Molecular Biology , VOL 7

State: Published (Approved)
Published: August 2021
Diamond Proposal Number(s): 13587 , 14435 , 15580 , 15836 , 15897 , 18598 , 21777

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.

Journal Keywords: Chromatin structure; Cytoskeletal proteins; Electron microscopy; SAXS; X-ray crystallography

Subject Areas: Biology and Bio-materials

Instruments: B21-High Throughput SAXS , I03-Macromolecular Crystallography , I24-Microfocus Macromolecular Crystallography

Added On: 10/08/2021 19:36

Discipline Tags:

Structural biology Life Sciences & Biotech

Technical Tags:

Diffraction Scattering Macromolecular Crystallography (MX) Small Angle X-ray Scattering (SAXS)