ジャーナル: Nat Commun / 年: 2023 タイトル: Origin and arrangement of actin filaments for gliding motility in apicomplexan parasites revealed by cryo-electron tomography. 著者: Matthew Martinez / Shrawan Kumar Mageswaran / Amandine Guérin / William David Chen / Cameron Parker Thompson / Sabine Chavin / Dominique Soldati-Favre / Boris Striepen / Yi-Wei Chang / 要旨: The phylum Apicomplexa comprises important eukaryotic parasites that invade host tissues and cells using a unique mechanism of gliding motility. Gliding is powered by actomyosin motors that ...The phylum Apicomplexa comprises important eukaryotic parasites that invade host tissues and cells using a unique mechanism of gliding motility. Gliding is powered by actomyosin motors that translocate host-attached surface adhesins along the parasite cell body. Actin filaments (F-actin) generated by Formin1 play a central role in this critical parasitic activity. However, their subcellular origin, path and ultrastructural arrangement are poorly understood. Here we used cryo-electron tomography to image motile Cryptosporidium parvum sporozoites and reveal the cellular architecture of F-actin at nanometer-scale resolution. We demonstrate that F-actin nucleates at the apically positioned preconoidal rings and is channeled into the pellicular space between the parasite plasma membrane and the inner membrane complex in a conoid extrusion-dependent manner. Within the pellicular space, filaments on the inner membrane complex surface appear to guide the apico-basal flux of F-actin. F-actin concordantly accumulates at the basal end of the parasite. Finally, analyzing a Formin1-depleted Toxoplasma gondii mutant pinpoints the upper preconoidal ring as the conserved nucleation hub for F-actin in Cryptosporidium and Toxoplasma. Together, we provide an ultrastructural model for the life cycle of F-actin for apicomplexan gliding motility.
凍結剤: ETHANE-PROPANE / チャンバー内湿度: 99 % / チャンバー内温度: 310 K / 装置: LEICA EM GP 詳細: Isolated tachyzoites were resuspended in media, and 4 uL was applied to the carbon side of the grid and front blotted for 4s.
詳細
Sample was averaged from within frozen-hydrated Toxoplasma gondii tachyzoites
位相板: VOLTA PHASE PLATE / エネルギーフィルター - 名称: GIF Bioquantum / エネルギーフィルター - スリット幅: 20 eV
試料ステージ
試料ホルダーモデル: FEI TITAN KRIOS AUTOGRID HOLDER
撮影
フィルム・検出器のモデル: GATAN K3 (6k x 4k) / 平均露光時間: 0.4 sec. / 平均電子線量: 2.3 e/Å2
実験機器
モデル: Titan Krios / 画像提供: FEI Company
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画像解析
抽出
トモグラム数: 9 / 使用した粒子像数: 373 / 手法: Volumes picked interactively / ソフトウェア - 名称: Dynamo (ver. 1.1.509) 詳細: Individual particles were picked and manually preoriented in IMOD. Particle coordinates and angles were imported into Dynamo
最終 角度割当
タイプ: NOT APPLICABLE / ソフトウェア - 名称: Dynamo (ver. 1.1.509)
最終 再構成
想定した対称性 - 点群: C1 (非対称) / 解像度のタイプ: BY AUTHOR / 解像度: 53.0 Å / 解像度の算出法: FSC 0.143 CUT-OFF / ソフトウェア - 名称: Dynamo (ver. 1.1.509) / 使用したサブトモグラム数: 373