Catastrophic depolymerization of microtubules driven by subunit shape change. Issue 10 (25th January 2018)

• Record Type: Journal Article
• Authors: Bollinger, Jonathan A.; Stevens, Mark J.
• Is Part Of: Soft matter. Volume 14:Issue 10(2018)
• Page Start: 1748
• Page End: 1752
• Publication Date: 2018-01-25
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c7sm02033c
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : Microtubules exhibit a dynamic instability between growth and catastrophic depolymerization. Abstract : Microtubules exhibit a dynamic instability between growth and catastrophic depolymerization. GTP-tubulin (αβ-dimer bound to GTP) self-assembles, but dephosphorylation of GTP- to GDP-tubulin within the tubule results in destabilization. While the mechanical basis for destabilization is not fully understood, one hypothesis is that dephosphorylation causes tubulin to change shape, frustrating bonds and generating stress. To test this idea, we perform molecular dynamics simulations of microtubules built from coarse-grained models of tubulin, incorporating a small compression of α-subunits associated with dephosphorylation in experiments. We find that this shape change induces depolymerization of otherwise stable systems via unpeeling "ram's horns" characteristic of microtubules. Depolymerization can be averted by caps with uncompressed α-subunits, i.e., GTP-rich end regions. Thus, the shape change is sufficient to yield microtubule behavior.