Increased microtubule lattice spacing correlates with selective binding of kinesin-1 in cells

Abstract

Within the cell cargo is transported via motor proteins walking along microtubules. The affinity of motor proteins for microtubules is controlled by various layers of regulation like tubulin isoforms, post- translational modifications and microtubule associated proteins. Recently, the conformation of the microtubule lattice has also emerged as a potential regulatory factor, but to what extent it acts as an additional layer of regulation has remained unclear. In this study, we used cryo-correlative light and electron microscopy to study microtubule lattices inside cells. We find that, while most microtubules have a compacted lattice (∼41 Å), a significant proportion of the microtubule cores have expanded lattice spacings and that these lattice spacings could be modulated by the microtubule stabilizing drug Taxol. Furthermore, kinesin-1 predominantly binds microtubules with a more expanded lattice spacing (∼41.6 Å). The different lattice spacings present in the cell can thus act as an additional factor that modulates the binding of motor proteins to specific microtubule subsets.