Microtubule Assembly Dynamics at the Nanoscale

Henry T. Schek, Melissa K. Gardner, Jun Cheng, David J. Odde, Alan J. Hunt

Research output: Contribution to journalArticle

127 Citations (Scopus)

Abstract

Background: The labile nature of microtubules is critical for establishing cellular morphology and motility, yet the molecular basis of assembly remains unclear. Here we use optical tweezers to track microtubule polymerization against microfabricated barriers, permitting unprecedented spatial resolution. Results: We find that microtubules exhibit extensive nanometer-scale variability in growth rate and often undergo shortening excursions, in some cases exceeding five tubulin layers, during periods of overall net growth. This result indicates that the guanosine triphosphate (GTP) cap does not exist as a single layer as previously proposed. We also find that length increments (over 100 ms time intervals, n = 16,762) are small, 0.81 ± 6.60 nm (mean ± standard deviation), and very rarely exceed 16 nm (about two dimer lengths), indicating that assembly occurs almost exclusively via single-subunit addition rather than via oligomers as was recently suggested. Finally, the assembly rate depends only weakly on load, with the average growth rate decreasing only 2-fold as the force increases 7-fold from 0.4 pN to 2.8 pN. Conclusions: The data are consistent with a mechanochemical model in which a spatially extended GTP cap allows substantial shortening on the nanoscale, while still preventing complete catastrophe in most cases.

Original languageEnglish (US)
Pages (from-to)1445-1455
Number of pages11
JournalCurrent Biology
Volume17
Issue number17
DOIs
StatePublished - Sep 4 2007

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guanosine triphosphate
Microtubules
microtubules
Guanosine Triphosphate
shortenings
Growth
Optical Tweezers
Optical tweezers
Tubulin
tubulin
Oligomers
Polymerization
polymerization
Dimers

Keywords

  • CELLBIO

Cite this

Microtubule Assembly Dynamics at the Nanoscale. / Schek, Henry T.; Gardner, Melissa K.; Cheng, Jun; Odde, David J.; Hunt, Alan J.

In: Current Biology, Vol. 17, No. 17, 04.09.2007, p. 1445-1455.

Research output: Contribution to journalArticle

Schek, Henry T. ; Gardner, Melissa K. ; Cheng, Jun ; Odde, David J. ; Hunt, Alan J. / Microtubule Assembly Dynamics at the Nanoscale. In: Current Biology. 2007 ; Vol. 17, No. 17. pp. 1445-1455.
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