Intrinsic Bending of Microtubule Protofilaments

SummaryThe complex polymerization dynamics of the microtubule (MT) plus end are closely linked to the hydrolysis of the GTP nucleotide bound to the β-tubulin. The destabilization is thought to be associated with the conformational change of the tubulin dimers from the straight conformation in the MT lattice to a curved conformation. It remains under debate whether this transformation is directly related to the nucleotide state, or a consequence of the longitudinal or lateral contacts in the MT lattice. Here, we present large-scale atomistic simulations of short tubulin protofilaments with both nucleotide states, starting from both extreme conformations. Our simulations indicate that both interdimer and intradimer contacts in both GDP and GTP-bound tubulin dimers and protofilaments in solution bend. There are no observable differences between the mesoscopic properties of the contacts in GTP and GDP-bound tubulin or the intradime and interdimer interfaces.

Graphical AbstractFigure optionsDownload full-size imageDownload high-quality image (341 K)Download as PowerPoint slideHighlights► GDP and GTP-bound tubulin protofilaments converge to a curved conformation ► No difference in mesoscopic properties of GDP and GTP filaments ► Rotation of the intermediate domain is not prevented by GTP ► Conformations resemble the 1SA2 structure closely with some additional contacts