Structure and Interactions of Plant Cell-Wall Polysaccharides by Two- and Three-Dimensional Magic-Angle-Spinning Solid-State NMR

Citations Over TimeTop 1% of 2011 papers

Abstract

The polysaccharide-rich cell walls (CWs) of plants perform essential functions such as maintaining tensile strength and allowing plant growth. Using two- and three-dimensional magic-angle-spinning (MAS) solid-state NMR and uniformly (13)C-labeled Arabidopsis thaliana, we have assigned the resonances of the major polysaccharides in the intact and insoluble primary CW and determined the intermolecular contacts and dynamics of cellulose, hemicelluloses, and pectins. Cellulose microfibrils showed extensive interactions with pectins, while the main hemicellulose, xyloglucan, exhibited few cellulose cross-peaks, suggesting limited entrapment in the microfibrils rather than extensive surface coating. Site-resolved (13)C T(1) and (1)H T(1ρ) relaxation times indicate that the entrapped xyloglucan has motional properties that are intermediate between the rigid cellulose and the dynamic pectins. Xyloglucan absence in a triple knockout mutant caused the polysaccharides to undergo much faster motions than in the wild-type CW. These results suggest that load bearing in plant CWs is accomplished by a single network of all three types of polysaccharides instead of a cellulose-xyloglucan network, thus revising the existing paradigm of CW structure. The extensive pectin-cellulose interaction suggests a central role for pectins in maintaining the structure and function of plant CWs. This study demonstrates the power of multidimensional MAS NMR for molecular level investigation of the structure and dynamics of complex and energy-rich plant materials.

Related Papers

• → Re-constructing our models of cellulose and primary cell wall assembly(2014)436 cited
• → Evidence for differential interaction mechanism of plant cell wall matrix polysaccharides in hierarchically-structured bacterial cellulose(2015)81 cited
• → The xyloglucan–cellulose assembly at the atomic scale(2006)141 cited
• → Xyloglucan in the primary cell wall: assessment by FESEM, selective enzyme digestions and nanogold affinity tags(2017)71 cited
• → Changes in pectic and hemicellulosic polysaccharides during acid pH-induced growth in pine hypocotyl segments(1989)15 cited