Life in the fast lane: actin-based motility of plant peroxisomes

Peroxisomal shape, distribution, motility, and interactions with cytoskeletal elements were examined during interphase in living leek (Allium porrum L.) epidermal cells transiently transformed with a construct encoding the green fluorescent protein bearing a carboxy-terminal type 1 peroxisomal targeting signal. Confocal laser scanning microscopy and time-course analysis revealed that labeled peroxisomes were either spherical or rod-shaped and possessed several types of motility including random oscillations, slow and fast directional and bidirectional movements, and stop-and-go movements. Co-localization studies indicated that most peroxisomes were in close association with actin filaments, while treatment of cells with the actin-disrupting drug cytochalasin D blocked all types of peroxisomal movements. In contrast, the overall spatial organization of peroxisomes and the microtubule cytoskeleton were different, and the microtubule-destabilizing agent oryzalin had no obvious effect on peroxisomal motility. These data indicate that the peroxisome in plant cells is a highly dynamic compartment that is dependent upon the actin cytoskeleton, not microtubules, for its subcellular distribution and movements.Key words: actin filaments, cytoskeleton, green fluorescent protein, leek, microtubules, peroxisomes.Les auteurs ont examiné la forme, la distribution, la motilité et les interactions avec les éléments du cytosquelette des peroxysomes, au cours de l'interphase, dans des cellules vivantes de l'épiderme du poireau (Allium porrum L.) temporairement transformées avec une structure codant pour la protéines verte fluorescente portant un carboxyl terminal de type I destiné à signaler les peroxysomes. La microscopie confocale par balayage au laser et des observations séquentielles révèlent que les peroxysomes marqués sont soit sphériques ou soit en forme de bâtonnet, et possèdent plusieurs types de motilité incluant l'oscillation aléatoire, ainsi que d