The Structure of the Catalytic Domain of a Plant Cellulose Synthase and Its Assembly into Dimers    . Issue 7 (10th July 2014)

• Record Type: Journal Article
• Authors: Olek, Anna T.; Rayon, Catherine; Makowski, Lee; Kim, Hyung Rae; Ciesielski, Peter; Badger, John; Paul, Lake N.; Ghosh, Subhangi; Kihara, Daisuke; Crowley, Michael; Himmel, Michael E.; Bolin, Jeffrey T.; Carpita, Nicholas C.
• Is Part Of: The Plant Cell. Volume 26:Issue 7(2014)
• Page Start: 2996
• Page End: 3009
• Publication Date: 2014-07-10
• DOI: 10.1105/tpc.114.126862
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract : Small-angle x-ray scattering gives a glimpse at the solution structure of the catalytic domains of plant cellulose synthase and their dimerization. Dimerization through the plant-specific sequences of the catalytic domain provides important clues for how Zn-finger domains couple these fundamental scaffold units into large, multimeric synthase complexes. Abstract: Cellulose microfibrils are para -crystalline arrays of several dozen linear (1→4)-β-d -glucan chains synthesized at the surface of the cell membrane by large, multimeric complexes of synthase proteins. Recombinant catalytic domains of rice ( Oryza sativa ) CesA8 cellulose synthase form dimers reversibly as the fundamental scaffold units of architecture in the synthase complex. Specificity of binding to UDP and UDP-Glc indicates a properly folded protein, and binding kinetics indicate that each monomer independently synthesizes single glucan chains of cellulose, i.e., two chains per dimer pair. In contrast to structure modeling predictions, solution x-ray scattering studies demonstrate that the monomer is a two-domain, elongated structure, with the smaller domain coupling two monomers into a dimer. The catalytic core of the monomer is accommodated only near its center, with the plant-specific sequences occupying the small domain and an extension distal to the catalytic domain. This configuration is in stark contrast to the domain organization obtained in predicted structures of plant CesA. The arrangement of the catalytic domain within the CesA monomer and dimer provides a foundation for constructing structural models of the synthase complex and defining the relationship between the rosette structure and the cellulose microfibrils they synthesize.