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Polysaccharide Structures in the Outer Mucilage of Arabidopsis Seeds Visualized by AFM.

Authors :
Williams MAK
Cornuault V
Irani AH
Symonds VV
Malmström J
An Y
Sims IM
Carnachan SM
Sallé C
North HM
Source :
Biomacromolecules [Biomacromolecules] 2020 Apr 13; Vol. 21 (4), pp. 1450-1459. Date of Electronic Publication: 2020 Mar 04.
Publication Year :
2020

Abstract

Evidence is presented that the polysaccharide rhamnogalacturonan I (RGI) can be biosynthesized in remarkably organized branched configurations and surprisingly long versions and can self-assemble into a plethora of structures. AFM imaging has been applied to study the outer mucilage obtained from wild-type (WT) and mutant ( bxl1-3 and cesa5-1 ) Arabidopsis thaliana seeds. For WT mucilage, ordered, multichain structures of the polysaccharide RGI were observed, with a helical twist visible in favorable circumstances. Molecular dynamics (MD) simulations demonstrated the stability of several possible multichain complexes and the possibility of twisted fibril formation. For bxl1-3 seeds, the imaged polymers clearly showed the presence of side chains. These were surprisingly regular and well organized with an average length of ∼100 nm and a spacing of ∼50 nm. The heights of the side chains imaged were suggestive of single polysaccharide chains, while the backbone was on average 4 times this height and showed regular height variations along its length consistent with models of multichain fibrils examined in MD. Finally, in mucilage extracts from cesa5-1 seeds, a minor population of chains in excess of 30 μm long was observed.

Details

Language :
English
ISSN :
1526-4602
Volume :
21
Issue :
4
Database :
MEDLINE
Journal :
Biomacromolecules
Publication Type :
Academic Journal
Accession number :
32058700
Full Text :
https://doi.org/10.1021/acs.biomac.9b01756