The companion of cellulose SYNTHASE 1 controls microtubule dynamics through a Tau-like mechanism to confer salt tolerance in plants
- School of Biosciences, University of Melbourne, Parkville 3010 VIC, Melbourne, Australia.
- Leibniz-Forschungsinstitut fur Molekulare Pharmakologie (FMP), NMR-supported Structural Biology, Robert-Rossle-Str. 10, 13125, Berlin, Germany.
Microtubules are filamentous structures necessary for cell division, motility and morphology. Microtubule dynamics are critically regulated by microtubule-associated proteins (MAPs). We outline the molecular mechanism by which the MAP, COMPANION OF CELLULOSE SYNTHASE1 (CC1), controls microtubule-bundling and dynamics in plants under salt stress conditions. CC1 contains an intrinsically disordered N-terminus that joins microtubules through conserved hydrophobic regions at evenly distributed foci. Structural data on the microtubule-bound CC1 N-terminus and mutation studies revealed the regions, and specific amino acids, that contribute to microtubule-binding. The importance of these regions and amino acids was confirmed through in vivo live cell imaging, which also explains how CC1 maintains cellulose synthesis during salt exposure. Surprisingly, the microtubule-binding mechanism of CC1 is remarkably similar to that of the prominent neuropathology-related protein Tau. Hence, we outline how MAP functions have converged during evolution across animal and plant cells.