Year: 2003
Type: article
Abstract: We have obtained a 3-D reconstruction of intact microtubules, using cryo-electron microscopy and image processing, at a resolution of about 8 Å, sufficient to resolve much of the secondary structure.Rather than use helical image processing methods, we have treated the microtubule images as strings of single particles.Since the structures of the alpha and beta monomers are so similar at this resolution, we can ignore the difference between them.The resulting map is thus an average of the alpha and beta tubulin structures.The level of detail in the map allows docking of the tubulin crystal structure with very strong constraints, providing several important insights not previously available through docking tubulin into lower resolution maps.This work provides an improved picture of the interactions between adjacent protofilaments that are responsible for microtubule stability and also suggests that some structural features are different in microtubules from those in the zinc sheets in which the tubulin structure was determined.The N-terminal loop is a major partner in forming the inter-protofilament interface with the M-loop.The small H6 domain is less involved in inter-protofilament contacts than in the crystals, and may be flexible enough to allow regulatory ligands such as Taxol to diffuse through the microtubule wall and bind to the inside surface.A cluster of residues that differ among beta tubulin isotypes is located at the site of major inter-protofilament interactions, which may relate to differences in dynamic properties and drug sensitivities observed for the different isotypes.
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: green
Awards: G1398330795, G1498294715
OpenAlex ID: W99499566