Cryo-ET of Toxoplasma parasites gives subnanometer insight into tubulin-based structures.

Autor:	Sun SY; Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA 94305., Segev-Zarko LA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305., Chen M; Verna Marrs and McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030., Pintilie GD; Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA 94305., Schmid MF; Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025., Ludtke SJ; Verna Marrs and McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030.; Cryo-EM Core, Baylor College of Medicine, Houston, TX 77030., Boothroyd JC; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305; jboothr@stanford.edu wahc@stanford.edu., Chiu W; Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA 94305; jboothr@stanford.edu wahc@stanford.edu.; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305.; Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2022 Feb 08; Vol. 119 (6).
DOI:	10.1073/pnas.2111661119
Abstrakt:	Tubulin is a conserved protein that polymerizes into different forms of filamentous structures in Toxoplasma gondii , an obligate intracellular parasite in the phylum Apicomplexa. Two key tubulin-containing cytoskeletal components are subpellicular microtubules (SPMTs) and conoid fibrils (CFs). The SPMTs help maintain shape and gliding motility, while the CFs are implicated in invasion. Here, we use cryogenic electron tomography to determine the molecular structures of the SPMTs and CFs in vitrified intact and detergent-extracted parasites. Subvolume densities from detergent-extracted parasites yielded averaged density maps at subnanometer resolutions, and these were related back to their architecture in situ. An intralumenal spiral lines the interior of the 13-protofilament SPMTs, revealing a preferred orientation of these microtubules relative to the parasite's long axis. Each CF is composed of nine tubulin protofilaments that display a comma-shaped cross-section, plus additional associated components. Conoid protrusion, a crucial step in invasion, is associated with an altered pitch of each CF. The use of basic building blocks of protofilaments and different accessory proteins in one organism illustrates the versatility of tubulin to form two distinct types of assemblies, SPMTs and CFs. Competing Interests: The authors declare no competing interest. (Copyright © 2022 the Author(s). Published by PNAS.)
Databáze:	MEDLINE
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