Evidence for In Vitro Binding of Pectin Side Chains to Cellulose

Abstract

Pectins of varying structures were tested for their ability to interact with cellulose in comparison to the well-known adsorption of xyloglucan. Our results reveal that sugar beet (Beta vulgaris) and potato (Solanum tuberosum) pectins, which are rich in neutral sugar side chains, can bind in vitro to cellulose. The extent of binding varies with respect to the nature and structure of the side chains. Additionally, branched arabinans (Br-Arabinans) or debranched arabinans (Deb-Arabinans; isolated from sugar beet) and galactans (isolated from potato) were shown bind to cellulose microfibrils. The adsorption of Br-Arabinan and galactan was lower than that of Deb-Arabinan. The maximum adsorption affinity of Deb-Arabinan to cellulose was comparable to that of xyloglucan. The study of sugar beet and potato alkali-treated cell walls supports the hypothesis of pectin-cellulose interaction. Natural composites enriched in arabinans or galactans and cellulose were recovered. The binding of pectins to cellulose microfibrils may be of considerable significance in the modeling of primary cell walls of plants as well as in the process of cell wall assembly.The well-known model of primary cell walls (PCWs) of dicotyledons emphasizes noncovalent interactions between cell wall polymers and suggests two independent, but interacting, networks where the cellulose-xyloglucan network is embedded in a matrix of pectic polysaccharides (Carpita and Gibeaut, 1993;Somerville et al., 2004).Cellulose, the primary structural element of the cell wall, is a homopolymer composed of (1/4)-linked b-D-Glcp residues. The linear chains of parallel alignment are tightly linked by hydrogen bonds to form microfibrils. Xyloglucan, the most abundant hemicellulosic polysaccharide in the PCWs of dicotyledons, is composed of a cellulose-like backbone consisting of (1/4)-linked b-D-Glcp residues, branched at O-6 by a-D-Xylp residues, which can be further substituted at O-2 by b-D-Galp residues (Fry, 1989). Some of the Galp residues may be substituted at O-6 by a-D-Fucp. Pectins are major components of dicotyledon PCWs and of the middle lamella. Their backbone is composed of smooth homogalacturonan (HG) and hairy rhamnogalacturonan (RG) I regions (O'Neill et al., 1990). HG, a linear chain composed of (1/4)-linked a-D-GalUAp units, can be methyl esterified at O-6 of carboxyl groups and acetyl esterified at O-2 and/or O-3 of secondary hydroxyl groups (Ralet et al., 2001). Some HGs might be substituted to form RG II or xylogalacturonan. RG II is a complex polysaccharide composed of GalUAp, Rhap, Galp, and some unusual sugars.Dimers of RG II were found to be cross-linked by two diester bonds through a boron atom (Fleischer et al., 1999). Xylogalacturonan contains b-D-Xylp residues attached to O-3 of the HG backbone (Le Goff et al., 2001). RG I contains a backbone of the repeating di- Renard et al., 1995). They are predominantly substituted at O-4 of Rhap residues by neutral sugar side chains (Schols and Voragen, 1994). The proportion of branched Rhap residues depen...

How does the cell wall ‘stick’ in the mucilage? A detailed microstructural analysis of the seed coat mucilaginous cell wall

“…We could therefore speculate that our results demonstrated that the fibrillary material covering the cellulose fibrils might correspond to the xylan chains. The cellulose-hemicellulose interaction is well accepted by many authors (Whitheny et al, 1999;Zykwinska et al, 2005Zykwinska et al, , 2007Caffall and Mohnen, 2009;Altaner and Jarvis, 2008;Scheller and Ulskov, 2010;Busse-Wicher et al, 2014).…”

“…When interacting with cellulose, the main components of the mucilage envelope are linear or branched polymers represented by pectins (e.g. RG I) and hemicelluloses (xyloglucan, xylan, arabinoxylan) (Zykwinska et al, 2005(Zykwinska et al, , 2007Naran et al, 2008;Scheller and Ulskov, 2010;Pak and Cosgrove, 2012;Western, 2012;Busse-Wicher et al, 2014;Cosgrove, 2014;Voiniciuc et al 2015a,b). We can surmise Our studies revealed the structural differences between two main types of mucilage.…”

“…The typical plant cell wall of dicotyledonous plants is a complex structure composed of three main groups of polysaccharides: cellulose, pectins and hemicellulose linked together by different bonds in the form of a spatial network (Somerville et al, 2004;Zykwinska et al, 2005Zykwinska et al, , 2007Donaldson, 2007;Jarvis, 2011). However, such a composition is more typical of the PCW, whereas the SCW mainly consists of cellulose and hemicelluloses and appears to be more structurally organized than the PCW in this instance (Bidlack et al, 1992).…”

Gradients in Wall Mechanics and Polysaccharides along Growing Inflorescence Stems

“…5B; Table IV). Among the five sets of a-L-Ara signals (Zykwinska et al, 2005), type a and type b Ara are unique to the inflorescence cell walls and absent in the seedling. Type a Ara shows a downfield C2 chemical shift of 87.8 ppm, indicating 2,5-linked a-L-Ara, while type b Ara exhibits downfield C2 and C3 chemical shifts of 85.8 and 81.1 ppm, suggesting 2,3,5-linked a-L-Ara.…”

Revision of adsorption models of xyloglucan on microcrystalline cellulose

“…Additionally, it has short side chains of xylose, galactose and often but not always a terminal fucose or arabinose, which prevent the assembly of xyloglucan into a crystalline cellulose-like microfibl. Tamarind xyloglucan is an example of non-fucosylated storage xyloglucan (Zykwinska et al 2008;Kozioł et al 2015), and its molar mass is estimated at 763 kDa (Zykwinska et al 2005). The conformation may partially resemble a flat ribbon, which is thought to be able to create hydrogen bond to the similar bglucan chains of cellulose on the surface of the microfibril (Albersheim et al 2011).…”