Organization of cellulose synthase complexes involved in primary cell wall synthesis in Arabidopsis thaliana.
In all land plants, cellulose is synthesized from hexameric plasma membrane complexes. Indirect evidence suggests that in vascular plants the complexes involved in primary wall synthesis contain three distinct cellulose synthase catalytic subunits (CESAs). In this study, we show that CESA3 and CESA6 fused to GFP are expressed in the same cells and at the same time in the hypocotyl of etiolated seedlings and migrate with comparable velocities along linear trajectories at the cell surface. We also show that CESA3 and CESA6 can be coimmunoprecipitated from detergent-solubilized extracts, their protein levels decrease in mutants for either CESA3, CESA6, or CESA1 and CESA3, CESA6 and also CESA1 can physically interact in vivo as shown by bimolecular fluorescence complementation. We also demonstrate that CESA6-related CESA5 and CESA2 are partially, but not completely, redundant with CESA6 and most likely compete with CESA6 for the same position in the cellulose synthesis complex. Using promoter-beta-glucuronidase fusions we show that CESA5, CESA6, and CESA2 have distinct overlapping expression patterns in hypocotyl and root corresponding to different stages of cellular development. Together, these data provide evidence for the existence of binding sites for three distinct CESA subunits in primary wall cellulose synthase complexes, with two positions being invariably occupied by CESA1 and CESA3, whereas at least three isoforms compete for the third position. Participation of the latter three isoforms might fine-tune the CESA complexes for the deposition of microfibrils at distinct cellular growth stages.
Desprez
Thierry
T
Laboratoire de Biologie Cellulaire, Unité de Recherche 501, Institut Jean-Pierre Bourgin-Institut National de la Recherche Agronomique, Route de St Cyr, 78026 Versailles Cedex, France.
Juraniec
Michal
M
Crowell
Elizabeth Faris
EF
Jouy
Hélène
H
Pochylova
Zaneta
Z
Parcy
Francois
F
Höfte
Herman
H
Gonneau
Martine
M
Vernhettes
Samantha
S
D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D002473:Cell Wall / Q000378:metabolism*; D002482:Cellulose / Q000737:chemistry; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005964:Glucosyltransferases / Q000737:chemistry* / Q000235:genetics; D020894:Microfibrils; D008957:Models, Genetic; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism; D020033:Protein Isoforms
D029681:Arabidopsis Proteins; D020033:Protein Isoforms; D002482:Cellulose; C516179:At5g05170 protein, Arabidopsis; C110227:CESA1 protein, Arabidopsis; C568259:CESA5 protein, Arabidopsis; D005964:Glucosyltransferases; C457769:PRC1 protein, Arabidopsis; C478648:cellulose synthase