Arabidopsis thaliana KORRIGAN1 protein: N-glycan modification, localization, and function in cellulose biosynthesis and osmotic stress responses.

Plant cellulose biosynthesis is a complex process involving cellulose-synthase complexes (CSCs) and various auxiliary factors essential for proper orientation and crystallinity of cellulose microfibrils in the apoplast. Among them is KORRIGAN1 (KOR1), a type-II membrane protein with multiple N-glycans within its C-terminal cellulase domain. N-glycosylation of the cellulase domain was important for KOR1 targeting to and retention within the trans-Golgi network (TGN), and prevented accumulation of KOR1 at tonoplasts. The degree of successful TGN localization of KOR1 agreed well with in vivo-complementation efficacy of the rsw2-1 mutant, suggesting non-catalytic functions in the TGN. A dynamic interaction network involving microtubules, CSCs, KOR1, and currently unidentified glycoprotein component(s) likely determines stress-triggered re-organization of cellulose biosynthesis and resumption of cell-wall growth under stress.