Visualization of cellulose synthase demonstrates functional association with microtubules

Abstract

Expression of a functional yellow fluorescent protein fusion to cellulose synthase (CESA) in transgenic Arabidopsis plants allowed the process of cellulose deposition to be visualized in living cells. Spinning disk confocal microscopy revealed that CESA complexes in the plasma membrane moved at constant rates in linear tracks that were aligned and were coincident with cortical microtubules. Within each observed linear track, complex movement was bidirectional. Inhibition of microtubule polymerization changed the fine-scale distribution and pattern of moving CESA complexes in the membrane, indicating a relatively direct mechanism for guidance of cellulose deposition by the cytoskeleton. C ellulose is synthesized in vascular plants by a plasma membrane–localized enzyme, cellulose synthase, that has been visualized by freeze fracture of plasma mem-branes as 25- to 30-nm-diameter symmetrical rosettes with six resolved subunits (1). Fro