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The multi‐scale architecture of mammalian sperm flagella and implications for ciliary motility
Author(s) -
Leung Miguel Ricardo,
Roelofs Marc C,
Ravi Ravi Teja,
Maitan Paula,
Henning Heiko,
Zhang Min,
Bromfield Elizabeth G,
Howes Stuart C,
Gadella Bart M,
BloomfieldGadêlha Hermes,
ZeevBenMordehai Tzviya
Publication year - 2021
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2020107410
Subject(s) - flagellum , biology , motile cilium , cilium , microtubule , axoneme , centriole , microbiology and biotechnology , motility , sperm , sperm motility , biophysics , genetics , bacteria
Motile cilia are molecular machines used by a myriad of eukaryotic cells to swim through fluid environments. However, available molecular structures represent only a handful of cell types, limiting our understanding of how cilia are modified to support motility in diverse media. Here, we use cryo‐focused ion beam milling‐enabled cryo‐electron tomography to image sperm flagella from three mammalian species. We resolve in‐cell structures of centrioles, axonemal doublets, central pair apparatus, and endpiece singlets, revealing novel protofilament‐bridging microtubule inner proteins throughout the flagellum. We present native structures of the flagellar base, which is crucial for shaping the flagellar beat. We show that outer dense fibers are directly coupled to microtubule doublets in the principal piece but not in the midpiece. Thus, mammalian sperm flagella are ornamented across scales, from protofilament‐bracing structures reinforcing microtubules at the nano‐scale to accessory structures that impose micron‐scale asymmetries on the entire assembly. Our structures provide vital foundations for linking molecular structure to ciliary motility and evolution.