Microtubule reorientation in the blue spotlight: Cutting and CLASPing at dynamic hot spots

Abstract

Microtubule reorientation into a longitudinal network during the phototropic response in Arabidopsis thaliana depends on their severing by katanin at crossovers. Lindeboom et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201805047) show that at newly generated plus ends, the anti-catastrophe activity of CLASP is essential for further growth.

Figure 1.

MT reorientation in response to blue light. (A) MT reorientation results from the severing (green circles) of MTs (colored arrows) that crossed transversal MTs (gray). Longitudinal network amplification results from the protection against disassembly of both the newly created minus and plus ends. (B) Katanin (green) concentrated at MT crossover cuts the youngest MT, and then CLASP (orange), although less concentrated than at other MT dynamic hot spots, prevents the disassembly of the newly created plus end, allowing its elongation (top path). Alternatively, a depolymerizing plus end may be rescued thanks to the presence of CLASP (bottom path).