Cellulose microfibril crystallinity is reduced by mutating C-terminal transmembrane region residues CESA1 A903V and CESA3 T942I of cellulose synthase

Darby M. Harris, Kendall Corbin, Tuo Wang, Ryan Gutierrez, Ana L. Bertolo, Carloalberto Petti, Detlef M. Smilgies, José Manuel Estevez, Dario Bonetta, Breeanna R. Urbanowicz, David W. Ehrhardt, Chris R. Somerville, Jocelyn K.C. Rose, Mei Hong, Seth DeBolt

Research output: Contribution to journalArticlepeer-review

120 Citations (Scopus)

Abstract

The mechanisms underlying the biosynthesis of cellulose in plants are complex and still poorly understood. A central question concerns the mechanism of microfibril structure and how this is linked to the catalytic polymerization action of cellulose synthase (CESA). Furthermore, it remains unclear whether modification of cellulose microfibril structure can be achieved genetically, which could be transformative in a bio-based economy. To explore these processes in planta, we developed a chemical genetic toolbox of pharmacological inhibitors and corresponding resistance-conferring point mutations in the C-terminal transmembrane domain region of CESA1 A903V and CESA3 T942I in Arabidopsis thaliana. Using 13C solidstate nuclear magnetic resonance spectroscopy and X-ray diffraction, we show that the cellulose microfibrils displayed reduced width and an additional cellulose C4 peak indicative of a degree of crystallinity that is intermediate between the surface and interior glucans of wild type, suggesting a difference in glucan chain association during microfibril formation. Consistent with measurements of lower microfibril crystallinity, cellulose extracts from mutated CESA1 A903V and CESA3 T942I displayed greater saccharification efficiency than wild type. Using live-cell imaging to track fluorescently labeled CESA, we found that these mutants show increased CESA velocities in the plasma membrane, an indication of increased polymerization rate. Collectively, these data suggest that CESA1 A903Vand CESA3 T942I have modified microfibril structure in terms of crystallinity and suggest that in plants, as in bacteria, crystallization biophysically limits polymerization.

Original languageEnglish
Pages (from-to)4098-4103
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number11
DOIs
Publication statusPublished - 13 Mar 2012
Externally publishedYes

Keywords

  • Cell wall
  • Polysaccharide
  • Quinoxyphen

ASJC Scopus subject areas

  • General

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