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

Lookup NU author(s): James Dunce, Dr Owen Davies

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Abstract

© 2021, The Author(s), under exclusive licence to Springer Nature America, Inc.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.

Publication metadata

Author(s): Dunce JM, Salmon LJ, Davies OR

Publication type: Article

Publication status: Published

Journal: Nature Structural and Molecular Biology

Year: 2021

Volume: 28

Issue: 8

Pages: 681-693

Print publication date: 01/08/2021

Online publication date: 09/08/2021

Acceptance date: 30/06/2021

ISSN (print): 1545-9993

ISSN (electronic): 1545-9985

Publisher: Nature Research

URL: https://doi.org/10.1038/s41594-021-00636-z

DOI: 10.1038/s41594-021-00636-z

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