Cellulose synthase complex

Direct microscopic evidence demonstrating that terminal complex particles are cellulose synthesizing enzymes is not currently available and will await the production of antibodies against cellulose synthase following its isolation and purification. However, the proposal that terminal complexes are part of the cellulose synthase complex is increasingly becoming accepted... 

Schematic model of the cellulose synthase complex crystalline cellulose I emerges from the rosette terminal complex, which is embedded in the plasma membrane. View from the top (above) and the side (below). (Adopted from Perez and Mazeau [42] and from Horii [40])...

Fig. 4. Cartoon representation of a cellulose synthase complex moving inside the plasma membrane, leaving a cellulose microfibril as one component of the primary cell-wall (inset transmission electron microscopy). The cellulose synthase complex becomes active while unattached to a microtubule. (See Color Plate 2.)...

T. Desprez, M. Jmaniec, E. F. Crowell, H. Jouy, Z. Pochylova, F. Parcy, H. Hofte, M. Gonneau, and S. Vemhettes, Organization of cellulose synthase complexes involved in the primary cell wall synthesis in Arabidopsis thaliana, Proc. Natl. Acad. Sci. U.S.A., 104 (2007) 15572-15577. 

F. Diotallevi and B. M. Mulder, The cellulose synthase complex A polymerization driven supramolecular motor, Biophys. J., 92 (2007) 2666-2673. 

Gardiner, J.C., Taylor, N.G., Turner, S.R. Control of cellulose synthase complex localization in developing xylem. Plant Cell 15, 1740-1748 (2003)... 

The isolation of mutants deficient in secondary cell wall cellulose synthesis has led to the identification of a number of genes essential for cellulose production. The identification of these genes and the discovery that three CesA proteins are involved in the same protein complex has answered some of the questions regarding the complexity of the cellulose synthase complex. That fact that all three proteins are required for the correct assembly and targeting of the complex to the plasma membrane will allow us to further dissect the roles of these and other proteins in cellulose synthesis. In addition, the identification of a protein that is involved in both primary and secondary cell wall cellulose synthesis may allow us to identify other common components between the primary and secondary cell wall cellulose synthesizing machinery. 

Korrigan was originally identified as an extremely dwarf mutant with a lesion in a plasma membrane-associated P-l,4-endoglucanase (Nicol et al. 1998). The Korrigan protein is believed to be involved in the cellulose synthase complex that functions during primary or secondary wall formation (Nicol et al. 1998 Molhoj et al. 2002 Szyjanowicz et al. 2004). Its exact function remains to be determined although given its relationship to the cellulase type of hydrolases, it has been... 

Dimerization of the CesA proteins has been proposed for the formation of a functional cellulose synthase complex (Scheible et al. 2001 Kurek et al. 2002). 

Cellulose microfibrils are deposited by cellulose synthases into the cell wall in often strikingly regular patterns. Here we discuss several mechanisms that have been put forward to explain the alignment of cellulose microfibrils that gives rise to ordered cell wall textures the hypothesis that cortical microtubules align cellulose microfibrils during their deposition, the liquid crystal hypothesis in which cellulose microfibrils self-assemble into textures after their deposition, the templated incorporation hypothesis, and the geometrical theory in which the density of active cellulose synthase complexes inside the plasma membrane may dictate the architecture of the cell wall. 

Indeed, in this recent work, it is shown in addition that when the cortical microtubules are completely depolymerized, cellulose synthase complexes move in highly ordered patterns ... 

The cytoskeleton has long been proposed to play a key role in cellular metabolism, serving as a matrix for the assembly, and even regulation, of enzyme complexes (reviewed in [10]). A striking example comes from the cellulose synthase complex of plants, an enzyme system that is currently of particular interest with regard to enhancing plant-based biofuels (reviewed in... 

This system is organized in vascular plants as a 30 nm diameter plasma membrane complex, known as the rosette TC, that was first described by Mueller and Brown more than 25 years ago [42]. The rosette is composed of an estimated 36 subunits comprising at least three types of cellulose synthase A proteins. All three components have been shown to be essential for correct assembly and enzymatic activity of the complex in Arabidopsis [43, 44]. The physical interaction of these three components has recently been demonstrated by bimolecular fluorescence complementation [45]. The system also offers a beautiful example of the functional aspects of this organization, as cortical microtubules guide the movement of cellulose synthase complexes through the plasma membrane during cell wall biosynthesis [46,47],... 

Persson, S. et al. (2007) Genetic evidence for three unique components in primary cell-wall cellulose synthase complexes in Arabidopsis. Proc. Natl Acad. Sci USA 104, 15566-15571... 

Fig. 14.4 A possible model of cellulose synthase complex. (Modified from Tonouchi 2015)...

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