Role of KORRIGAN1 in the synthesis of cellulose.
Cell Biology Laboratory, Institut Jean-Pierre Bourgin, INRA, Versailles, France.
During my master project at INRA in Versailles, I was involved in a study KORRIGAN1, the protein involved in cellulose synthesis. Cellulose is the most abundant biopolymer on earth. It shows a unique structure with remarkable mechanical properties. It consists of crystalline assemblies of parallel linked glucan chains, which show a tensile strength comparable to that of steel. The synthesis of cellulose requires a specialized cellular machinery composed of a plasma membrane-embedded protein complexes. The endo-1,4-b-D-glucanase KORRIGAN1 (KOR1) is an essential enzyme for cellulose synthesis. Using immunofluorescence and GFP:KOR1, we investigated the distribution of KOR1 in epidermal cells in the root meristem. We found that KOR1 was localized in intracellular compartments corresponding to a Golgi apparatus, early endosomes, and the tonoplast. Inhibition of cellulose synthesis by isoxaben promoted a net redistribution of KOR1 toward a homogeneous population of compartments, distinct from early endosomes, concentrated close to the plasma membrane. A redistribution of KOR1 away from early endosomes was also observed in the same cells at later stages of cell elongation. A subpopulation of KOR1–containing compartments followed trajectories along the plasma membrane, and this motility required intact microtubules. Finally, we also showed that phosphorylation status of KOR1 is important for its subcellular localization. These observations demonstrate that the deposition of cellulose, like chitin synthesis in yeast, involves the regulated intracellular cycling of at least one enzyme required for its synthesis.
“An Arabidopsis Endo-1,4-b-D-Glucanase Involved in Cellulose Synthesis Undergoes Regulated
Intracellular Cycling” Robert S., Bichet A., Grandjean O., Kierzkowski D., Satiat-Jeunemaıtre B.,
Pelletier S., Hauser M-T., Hofte H., and Vernhettes S.
The Plant Cell 17, 3378–3389 (2005) Reprint.