JXB Advance Access published online on May 20, 2008
Journal of Experimental Botany, doi:10.1093/jxb/ern125
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© 2008 The Author(s).
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RESEARCH PAPER |
Features of the primary wall CESA complex in wild type and cellulose-deficient mutants of Arabidopsis thaliana
Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 2601, Australia
* To whom correspondence should be addressed. E-mail: richard.williamson{at}anu.edu.au
Evidence from genetics, co-precipitation and bimolecular fluorescence complementation suggest that three CESAs implicated in making primary wall cellulose in Arabidopsis thaliana form a complex. This study shows the complex has a Mr of approximately 840 kDa in detergent extracts and that it has undergone distinctive changes when extracts are prepared from some cellulose-deficient mutants. The mobility of CESAs 1, 3, and 6 in a Triton-soluble microsomal fraction subject to blue native polyacrylamide gel electrophoresis was consistent with a Mr of about 840 kDa. An antibody specific to any one CESA pulled down all three CESAs consistent with their occupying the same 840 kDa complex. In rsw1, a CESA1 missense mutant, extracts of seedlings grown at the permissive temperature have an apparently normal CESA complex that was missing from extracts of seedlings grown at the restrictive temperature where CESAs precipitated independently. In prc1-19, with no CESA6, CESAs 1 and 3 were part of a 420 kDa complex in extracts of light-grown seedlings that was absent from extracts of dark-grown seedlings where the CESAs precipitated independently. Two CESA3 missense mutants retained apparently normal CESA complexes as did four cellulose-deficient mutants defective in proteins other than CESAs. The 840 kDa complex could contain six CESA subunits and, since loss of plasma membrane rosettes accompanies its loss in rsw1, the complex could form one of the six particles which electron microscopy reveals in rosettes.
Key words: Arabidopsis thaliana, cellulose synthase, CESA complex, membrane proteins, primary wall, rsw mutants
Received 10 February 2008; Revised 1 April 2008 Accepted 2 April 2008