RT Journal Article
SR Electronic
T1 Cryo-tomography reveals rigid-body motion and organization of apicomplexan invasion machinery
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.04.23.489287
DO 10.1101/2022.04.23.489287
A1 Gui, Long
A1 O’Shaughnessy, William J.
A1 Cai, Kai
A1 Reetz, Evan
A1 Reese, Michael L.
A1 Nicastro, Daniela
YR 2023
UL http://biorxiv.org/content/early/2023/01/14/2022.04.23.489287.abstract
AB The apical complex is a specialized collection of cytoskeletal and secretory machinery in apicomplexan parasites, which include the pathogens that cause malaria and toxoplasmosis. Its structure and mechanism of motion are poorly understood. We used cryo-FIB-milling and cryo-electron tomography to visualize the 3D-structure of the apical complex in its protruded and retracted states. Averages of conoid-fibers revealed their polarity and unusual nine-protofilament arrangement with associated proteins connecting and likely stabilizing the fibers. Neither the structure of the conoidfibers nor the architecture of the spiral-shaped conoid complex change during protrusion or retraction. Thus, the conoid moves as a rigid body, and is not spring-like and compressible, as previously suggested. Instead, the apical-polar-rings (APR), previously considered rigid, dilate during conoid protrusion. We identified actin-like filaments connecting the conoid and APR during protrusion, suggesting a role during conoid movements. Furthermore, our data capture the parasites in the act of secretion during conoid protrusion.Competing Interest StatementThe authors have declared no competing interest.