Desprez T., Juraniec M., Crowell E. F., Jouy H., Pochylova Z., Parcy F., Höfte H., Gonneau M., Vernhettes S.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
104:
15572-15577,
2007
Keywords:
Abstract:
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--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.
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IEB authors: Žaneta Pochylová
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