Nuggets

Nuggets of Science – bite sized highlights of CLSF research

Cryo EM Structure of a Trimeric Cellulose Synthase Complex

Supramolecular plant cellulose synthase complexes organize multiple linear glucose polymers into microfibrils as load-bearing wall components. We determined the structure of a poplar cellulose synthase CesA homotrimer that suggests a molecular basis for cellulose microfibril formation. This complex, stabilized by cytosolic plant conserved regions and helical exchange within the transmembrane segment, forms three channels occupied by nascent cellulose polymers. Secretion steers the polymers toward a common exit point, which may facilitate protofibril formation. CesAs’ N-terminal domains assemble into a cytosolic stalk that interacts with a microtubule-tethering protein and may thus be involved in CesA localization.

This structure provides a detailed entry point for investigating how the enzyme works, how three of the enzymes assemble into trimeric subunits, and how six of the subunits assemble into the cellulose synthesis complex which makes the cellulose microfibril. The microfibril in turn is at the heart of lignocellulosic materials that store carbon and solar energy captured in photosynthesis. The structure is also key to engineering cellulose for novel properties (reduced recalcitrance, changes in microfibril shape, length, crystallinity, surface properties and so on).   – Jochen Zimmer

Read more at:

Read more about the relevance of these findings on formation of plant cell walls.

Full Research article:  Pallinti, P., Ho, R., Zimmer, J. 2020. Architecture of a catalytically active homotrimeric plant cellulose synthase complex. Science 369: 1089-1094, DOI: 10.1126/science.abb2978

____________________________________________________________________________