Abstract
The resolution of subtomogram averages calculated from cryo-electron tomograms (cryo-ET) of crowded cellular environments is often limited due to signal loss in, and misalignment of the subtomograms. In contrast, single-particle cryo-electron microcopy (SP-cryo-EM) routinely reaches near-atomic resolution of isolated complexes. We developed a novel hybrid-method called “TomographY-Guided 3D REconstruction of Subcellular Structures” (TYGRESS) that combines cryo-ET with SP-cryo-EM to achieve close-to-nanometer resolution of complexes inside crowded environments. Using TYGRESS, we determined the native 3D structures of the intact ciliary axoneme with up to 12 Å resolution. These results reveal many structures and details that were not visible by cryo-ET. TYGRESS is generally applicable to cellular complexes that are amenable to subtomogram averaging, bringing us a step closer to (pseudo-)atomic models of cells.
One Sentence Summary A hybrid cryo-electron microscopy method reveals subcellular structures at unprecedented resolution.
Footnotes
Abbreviation: Cryo-electron tomography: cryo-ET; Contrast transfer function: CTF; Doublet microtubules: DMTs; Inner dynein arms: IDAs; I1 tether/tether head: I1 T/TH; Inner junction: IJ; Microtubule-associated proteins: MAPs; Microtubule inner proteins: MIPs; Nexin-dynein regulatory complex: N-DRC; Outer dynein arms: ODAs; Protofilaments: PFs; Radial spokes: RSs; Single-particle cryo-EM: SP-cryo-EM; TomographY-Guided 3D REconstruction of Subcellular Structures, TYGRESS.
