READING AND WRITING LATTICE SPACING: AN ADDITIONAL LAYER OF MICROTUBULE REGULATION

Abstract

Microtubules are dynamic cytoskeletal polymers whose assembly and remodeling depend on the polymerization of ab-tubulin dimers into a cylindrical lattice. Their growth is sustained by the addition of GTP-tubulin at the plus end, forming a stabilizing GTP cap that regulates transitions between growth and shrinkage. Dynamic instability underlies the ability of microtubules to generate mechanical forces and reorganize cellular architecture. Internal and external signals such as lattice defects, mechanical stress, microtubule-associated protein (MAP) binding, and post-translational modifications (PTMs) influence microtubule stability and dynamics. In this context, changes in lattice spacing, i.e., the longitudinal length of the tubulin dimer along protofilaments, emerge as an additional layer to microtubule regulation. Here, we review recent studies showing that microtubules exist in both compacted and expanded lattice states, with their relative prevalence governed by nucleotide hydrolysis, mechanical forces, and binding of MAPs. Collectively, these findings support a lattice-centric model in which lattice spacing contributes to the modulation of microtubule dynamics and cellular functions.