PT  - JOURNAL ARTICLE
AU  - S. S. Wijeratne
AU  - M. Marchan
AU  - J. S. Tresback
AU  - R. Subramanian
TI  - Distinct Protofilament-scale Dynamics Define the Differential Remodeling of Microtubule Arrays
AID  - 10.1101/2020.12.22.423986
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.12.22.423986
4099  - http://biorxiv.org/content/early/2020/12/23/2020.12.22.423986.short
4100  - http://biorxiv.org/content/early/2020/12/23/2020.12.22.423986.full
AB  - The intrinsic dynamic instability of microtubules and their control by associated enzymes, such as depolymerases, are essential for the organization of complex multi-microtubule arrays like spindle and axoneme. However, existing optical or electron-microscopy methods lack the spatial-temporal resolution to observe the dynamics of individual microtubules within arrays. We use Atomic Force Microscopy (AFM) to image depolymerizing arrays at single microtubule and protofilament resolution. We discover previously unseen modes of microtubule destabilization by conserved depolymerases. The kinesin-13 MCAK mediates asynchronous protofilament depolymerization and lattice-defect propagation, whereas the kinesin-8 Kip3p promotes synchronous protofilament depolymerization. Unexpectedly, MCAK can depolymerize axonemal doublets but Kip3p cannot. We propose that distinct protofilament-level activities underlie the functional dichotomy of depolymerases, resulting in either large-scale destabilization or length regulation of microtubule arrays. Our work establishes AFM as a powerful strategy to visualize microtubule dynamics and reveals how nanometer-scale substrate specificity leads to differential remodeling of micron-sized cytoskeletal structures.Competing Interest StatementThe authors have declared no competing interest.