Feedback microtubule control and microtubule-actin cross-talk in Arabidopsis revealed by integrative proteomic and cell biology analysis of KATANIN 1 mutants [Research]

Microtubule organization and dynamics are critical for key developmental processes such as cell division, elongation and morphogenesis. Microtubule severing is an essential regulator of microtubules, and is exclusively executed by KATANIN 1 in Arabidopsis. In this study we comparatively studied the proteome-wide effects in two KATANIN 1 mutants. Thus, shot-gun proteomic analysis of roots and aerial parts of single nucleotide mutant fra2 and T-DNA insertion mutant ktn1-2 was carried out. We have detected 42 proteins differentially abundant in both fra2 and ktn1-2. KATANIN 1 dysfunction altered abundances of proteins involved in development, metabolism and stress responses. The differential regulation of tubulins and microtubule-destabilizing protein MDP25 implied a feedback microtubule control in KATANIN 1 mutants. Furthermore, deregulation of profilin 1, actin depolymerizing factor 3 and actin 7 was observed. These findings were confirmed by immunoblotting analysis of actin and by microscopic observation of actin filaments using fluorescently-labeled phalloidin. Results obtained by qRT-PCR analysis revealed that changed protein abundances were not a consequence of altered expression levels of corresponding genes in the mutants. In conclusion, we show that abundances of several cytoskeletal proteins as well as organization of microtubules and the actin cytoskeleton are amended in accordance with defective microtubule severing.

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