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J Cell Biol. 2010 Nov 1;191(3):463-70. doi: 10.1083/jcb.201007081. Epub 2010 Oct 25.

Template-free 13-protofilament microtubule-MAP assembly visualized at 8 A resolution.

Author information

1
Institute of Structural and Molecular Biology, Birkbeck College, London, England, UK.

Abstract

Microtubule-associated proteins (MAPs) are essential for regulating and organizing cellular microtubules (MTs). However, our mechanistic understanding of MAP function is limited by a lack of detailed structural information. Using cryo-electron microscopy and single particle algorithms, we solved the 8 Å structure of doublecortin (DCX)-stabilized MTs. Because of DCX's unusual ability to specifically nucleate and stabilize 13-protofilament MTs, our reconstruction provides unprecedented insight into the structure of MTs with an in vivo architecture, and in the absence of a stabilizing drug. DCX specifically recognizes the corner of four tubulin dimers, a binding mode ideally suited to stabilizing both lateral and longitudinal lattice contacts. A striking consequence of this is that DCX does not bind the MT seam. DCX binding on the MT surface indirectly stabilizes conserved tubulin-tubulin lateral contacts in the MT lumen, operating independently of the nucleotide bound to tubulin. DCX's exquisite binding selectivity uncovers important insights into regulation of cellular MTs.

PMID:
20974813
PMCID:
PMC3003314
DOI:
10.1083/jcb.201007081
[Indexed for MEDLINE]
Free PMC Article

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