EMD-15733
Microtubule decorated with kinesin-motor domains, 13 protofilaments, 3-start helix, 1 seam
EMD-15733
Subtomogram averaging43.3 Å
Deposition: 05/09/2022Map released: 21/09/2022
Last modified: 13/12/2023
Sample Organism:
Xenopus laevis,
Homo sapiens
Sample: Microtubule assembled in Xenopus egg cytoplasmic extract and decorated with kinesin-motor domain Kif5B
Raw data: EMPIAR-11263
Deposition Authors: Chretien D
,
Guyomar C
Sample: Microtubule assembled in Xenopus egg cytoplasmic extract and decorated with kinesin-motor domain Kif5B
Raw data: EMPIAR-11263
Deposition Authors: Chretien D
,
Guyomar C
Changes in seam number and location induce holes within microtubules assembled from porcine brain tubulin and in Xenopus egg cytoplasmic extracts.
Guyomar C ,
Bousquet C ,
Ku S,
Heumann JM,
Guilloux G ,
Gaillard N ,
Heichette C,
Duchesne L ,
Steinmetz MO ,
Gibeaux R ,
Chretien D
(2022) eLife , 11
,
Bousquet C ,
Ku S,
Heumann JM,
Guilloux G ,
Gaillard N ,
Heichette C,
Duchesne L ,
Steinmetz MO ,
Gibeaux R ,
Chretien D
(2022) eLife , 11
Abstract:
Microtubules are tubes of about 25 nm in diameter that are critically involved in a variety of cellular functions, including motility, compartmentalization, and division. They are considered as pseudo-helical polymers whose constituent αβ-tubulin heterodimers share lateral homotypic interactions, except at one unique region called the seam. Here, we used a segmented sub-tomogram averaging strategy to reassess this paradigm and analyze the organization of the αβ-tubulin heterodimers in microtubules assembled from purified porcine brain tubulin in the presence of GTP and GMPCPP, and in Xenopus egg cytoplasmic extracts. We find that in almost all conditions, microtubules incorporate variable protofilament and/or tubulin subunit helical-start numbers, as well as variable numbers of seams. Strikingly, the seam number and location vary along individual microtubules, generating holes of one to a few subunits in size within their lattices. Together, our results reveal that the formation of mixed and discontinuous microtubule lattices is an intrinsic property of tubulin that requires the formation of unique lateral interactions without longitudinal ones. They further suggest that microtubule assembly is tightly regulated in a cytoplasmic environment.
Microtubules are tubes of about 25 nm in diameter that are critically involved in a variety of cellular functions, including motility, compartmentalization, and division. They are considered as pseudo-helical polymers whose constituent αβ-tubulin heterodimers share lateral homotypic interactions, except at one unique region called the seam. Here, we used a segmented sub-tomogram averaging strategy to reassess this paradigm and analyze the organization of the αβ-tubulin heterodimers in microtubules assembled from purified porcine brain tubulin in the presence of GTP and GMPCPP, and in Xenopus egg cytoplasmic extracts. We find that in almost all conditions, microtubules incorporate variable protofilament and/or tubulin subunit helical-start numbers, as well as variable numbers of seams. Strikingly, the seam number and location vary along individual microtubules, generating holes of one to a few subunits in size within their lattices. Together, our results reveal that the formation of mixed and discontinuous microtubule lattices is an intrinsic property of tubulin that requires the formation of unique lateral interactions without longitudinal ones. They further suggest that microtubule assembly is tightly regulated in a cytoplasmic environment.