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Nicholas C Carpita

Botany and Plant Pathology 

  • Professor
Lilly Hall Room 1-464

Cellulose structure and biosynthesis

With more than 200 billion tons per year in the natural environment, cellulose is the most abundant biopolymer on Earth. Cellulose microfibrils, the fundamental scaffolding of the plant cell wall, is a para-crystalline array of several dozen (1->4)-b-D-glucan chains synthesized at the plasma membrane surface by large multicomponent complexes of cellulose synthase (CesA) proteins. We discovered that recombinant catalytic domains of CesA are two-domain structures that dimerize using Small-Angle X-ray Scattering (SAXS) experiments to derive 3-D surface contour structures (Olek et al. 2014). The catalytic domains of plant CesAs contain two unique sequences not found in prokaryotic ancestors ­– a Plant-Conserved Region (P-CR) and Class-Specific Region (CSR) of unknown function. Molecular docking experiments with the catalytic core predicted that the CSRs of CesAs are the dimerization domains. We aim to provide the first crystal structure of a plant CesA catalytic domain. Towards that goal, we crystallized a recombinant Plant-Conserved Region (P-CR) and showed that it is primarily a coiled-coil domain positioned near the entrance to the active site of the catalytic core (Rushton et al. 2016). With Wen Jiang (Purdue) we have begun studies to define the assembly of CesAs into complexes at the Golgi membrane as part of a broader effort to characterize the dynamics of the Golgi proteome.  From substrate binding stoichiometry, we know that each CesA protein synthesizes a single (1->4)-b-D-glucan chain of a microfibril (Olek et al. 2014). We developed a modified TEMPO-catalyzed oxidation of glucose to uronosyl residues followed by carboxyl reduced with NaBD4 to provide a novel method for determining proportion of disordered surfaced chains, ordered surface chains in which only one-half of the residues are exposed to water, and completely anhydrous core-crystalline residues for cellulose microfibrils in biomass. Microfibrils of primary or secondary walls from seedlings and lignocellulosic biomass have significantly higher content of their glucan chains in anhydrous domains, indicating cellulose microfibrils into bundles with extensive crystalline continuity.


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Awards & Honors

(2014) 2014 Team Award. College of Agriculture.

(2010) President of American Society of Plant Biologist. American Society of Plant Biologist.

(2015) Seeds of Success Award, Millionaire's Club. College of Agriculture.

(2009) Fellow of American Society of Plant Biologists. American Society of Plant Biologists.

(1991) Agricultural Research Award. Purdue University.

(1987) Gamma Sigma Delta. Purdue University.

(1984) Sigma Xi. Purdue University.


Carpita, N. C., Hodges, T. K., & Antunes, M. Benzoate inducible promoters and promoter systems are disclosed, and uses thereof. Polynucleotides disclosing Benzoate Response Elements are also disclosed.. U.S. Patent No. 07705203. Washington, D.C.: U.S. Patent and Trademark Office.

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