The Microtubule Plus-End Tracking Protein ARMADILLO-REPEAT KINESIN1 Promotes Microtubule Catastrophe in Arabidopsis

Microtubule dynamics are critically important for plant cell development. Here, we show that Arabidopsis thaliana ARMADILLOREPEAT KINESIN1 (ARK1) plays a key role in root hair tip growth by promoting microtubule catastrophe events. This destabilizing activity appears to maintain adequate free tubuli...

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Bibliographic Details
Published in:The Plant cell 2014-08, Vol.26 (8), p.3372-3386
Main Authors: Eng, Ryan Christopher, Wasteneys, Geoffrey O.
Format: Article
Language:English
Subjects:
Arabidopsis - growth & development
Arabidopsis - metabolism
Arabidopsis - ultrastructure
Arabidopsis Proteins - analysis
Arabidopsis Proteins - metabolism
Arabidopsis Proteins - physiology
Binding Sites
Cell growth
Dinitrobenzenes - pharmacology
Disasters
Epidermal cells
Fluorescence
Kinesin - analysis
Kinesin - metabolism
Kinesin - physiology
Microtubules
Microtubules - metabolism
Microtubules - ultrastructure
Phenotypes
Plant cells
Plant Roots - growth & development
Plant Roots - metabolism
Plant Roots - ultrastructure
Plants
Protein Structure, Tertiary
Proteins
Root hairs
Sulfanilamides - pharmacology
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Summary:Microtubule dynamics are critically important for plant cell development. Here, we show that Arabidopsis thaliana ARMADILLOREPEAT KINESIN1 (ARK1) plays a key role in root hair tip growth by promoting microtubule catastrophe events. This destabilizing activity appears to maintain adequate free tubulin concentrations in order to permit rapid microtubule growth, which in turn is correlated with uniform tip growth. Microtubules in ark1-1 root hairs exhibited reduced catastrophe frequency and slower growth velocities, both of which were restored by low concentrations of the microtubule-destabilizing drug oryzalin. An ARK1-GFP (green fluorescent protein) fusion protein expressed under its endogenous promoter localized to growing microtubule plus ends and rescued the ark1-1 root hair phenotype. Transient overexpression of ARK1-RFP (red fluorescent protein) increased microtubule catastrophe frequency. ARK1-fusion protein constructs lacking the N-terminal motor domain still labeled microtubules, suggesting the existence of a second microtubule binding domain at the C terminus of ARK1. ARK1-GFP was broadly expressed in seedlings, but mutant phenotypes were restricted to root hairs, indicating that ARK1's function is redundant in cells other than those forming root hairs.
ISSN:1040-4651
1532-298X
DOI:10.1105/tpc.114.126789