Chalmers Conferences, 9th European Conference on Mathematical and Theoretical Biology

Understanding the paradoxical effects of katanin microtuble severing on the self-organisation of the plant cortical array
Eva E. Deinum, Simon H. H Tindemans, Bela M. Mulder

Last modified: 2014-06-09


Plant cells can adopt a wide variety of shapes driven by anisotropic growth.  This growth anisotropy is due to the anisotropic deposition of wall material, which is guided by an ordered population of microtubules attached to the cell membrane of interphase cells, the so-called cortical array. These microtubules interact through frequent collisions, whose angle-dependent outcomes have been shown to be sufficient to cause spontaneous alignment.

Recently, several  high-profile experimental papers have appeared on the microtubule severing protein complex katanin. Strikingly, katanin has paradoxical effects on microtubule alignment in the plant cortical array. At first sight one expects that severing reduces average microtubule length and life time and thus the number of microtubule collisions, thus diminishing the driving force for spontaneous alignment. Katanin action, however, apparently appears to promote alignment in planta. The latest experiments show that severing specifically at crossover sites is crucial for this alignment promoting effect.

Using computer simulations and theoretical approaches we now show how these findings combine into an alignment promoting mechanism. With virtual ``mutants'' we are able to demonstrate that crossover severing can only promote alignment if shallow angle interactions are protected from severing. In wild type cells,  zippering, the typical result of shallow angle encounters, naturally provides this protection.