Fine structure of the arabinogalactan-protein from Lolium multiflorum

Bacic, Antony; Churms, Shirley C.; Stephen, Alistair M.; Cohen, Peter B.; Fincher, Geoffrey B.

doi:10.1016/0008-6215(87)80203-3

Cited by 53 publications

(30 citation statements)

References 29 publications

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“…For example, although all Hyp-arabinogalactans possess a galactan backbone with arabinosyl side chains, some lack the abundant uronic acid residues prevalent in the Hyp-arabinogalactans of tobacco (44,45) where charge repulsions of the uronic acid residues may form a compression buffer at the cell surface analogous to animal proteoglycan compression buffers (15). On the other hand, the close proximity of glucuronic acid residues may favor Ca 2ϩ chelation (supplemental Fig.…”

Section: Discussionmentioning

confidence: 99%

Plant O-Hydroxyproline Arabinogalactans Are Composed of Repeating Trigalactosyl Subunits with Short Bifurcated Side Chains

Várnai

Lamport

et al. 2010

Journal of Biological Chemistry

104

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Classical arabinogalactan proteins partially defined by type II O-Hyp-linked arabinogalactans (Hyp-AGs) are structural components of the plant extracellular matrix. Recently we described the structure of a small Hyp-AG putatively based on repetitive trigalactosyl subunits and suggested that AGs are less complex and varied than generally supposed. Here we describe three additional AGs with similar subunits. The Hyp-AGs were isolated from two different arabinogalactan protein fusion glycoproteins expressed in tobacco cells; that is, a 22-residue Hyp-AG and a 20-residue Hyp-AG, both isolated from interferon ␣2b-(Ser-Hyp) 20 , and a 14-residue Hyp-AG isolated from (Ala-Hyp) 51 -green fluorescent protein. We used NMR spectroscopy to establish the molecular structure of these Hyp-AGs, which share common features: (i) a galactan main chain composed of two 133 ␤-linked trigalactosyl blocks linked by a ␤-136 bond; (ii) bifurcated side chains with Ara, Rha, GlcUA, and a Gal 6-linked to Gal-1 and Gal-2 of the main-chain trigalactosyl repeats; (iii) a common side chain structure composed of up to six residues, the largest consisting of an136)-unit, both linked to Gal. The conformational ensemble obtained by using nuclear Overhauser effect data in structure calculations revealed a galactan main chain with a reverse turn involving the ␤-136 link between the trigalactosyl blocks, yielding a moderately compact structure stabilized by H-bonds.Hydroxyproline-rich glycoproteins of the cell surface comprise groups of related structural proteins, including the extensins that form cell wall scaffolding networks essential for cytokinesis (1) and the classical arabinogalactan proteins (2) that are largely at the membrane wall interface (3) and have diverse functions (4). O-Hyp 6 glycosylation characterizes the hydroxyproline-rich glycoproteins and is of much interest as it defines molecular properties and, hence, biological function. Arabinogalactan proteins are highly glycosylated mainly with O-Hyp-arabinogalactan polysaccharides (5, 6). Extensins are less highly glycosylated mainly with small O-Hyp arabinooligosaccharides (7,8), whereas the related proline-rich proteins are minimally glycosylated also with arabinooligosaccharides (9). Peptide sequence directs O-Hyp glycosylation by the addition of small oligosaccharides to contiguous Hyp residues and larger acidic arabinogalactan polysaccharides to clustered noncontiguous Hyp (10, 11). For example, clustered Ala-Hyp and Ser-Hyp are typical AGP glycosylation motifs (12), whereas the Hyp residues in repetitive blocks of Ser-Hyp 2 orSer-Hyp 4 are arabinosylated. The "hyperglycosylation" of closely related AGPs complicates their purification, a problem that can be overcome by expressing single individual AGPs as GFP fusion glycoproteins, the hydrophobic GFP tag enabling chromatographic purification (13,14). This approach also allows purification of neoAGPs containing single repeating AGP glycosylation motifs, for example (Ala-Hyp) n or (Ser-Hyp) n , for base-catalyzed peptide bond hydrol...

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Section: Discussionmentioning

confidence: 99%

Plant O-Hydroxyproline Arabinogalactans Are Composed of Repeating Trigalactosyl Subunits with Short Bifurcated Side Chains

Várnai

Lamport

et al. 2010

Journal of Biological Chemistry

104

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“…There are also alternative proposed structures of some AGPs to our model of long-chain b-1,3-galactan. Tan et al (2010) propose a repetitive main chain of two b-1,3-galactosyl residues and a kink of b-1,6-linked Gal, whereas others postulate a kink (of unknown nature) in the main chain spaced at seven or more Gal residues (Churms et al, 1983;Bacic et al, 1987;Ellis et al, 2010). Although we did not examine the Yariv reactivity of such a kinked main chain, a kink spaced at seven or more residues might not disrupt the helical structure of the main chain, particularly if it is a kink of b-1,6-linked Gal, since the b-1,6-linkage is generally flexible compared with other types of linkages (Rees and Scott, 1971).…”

Section: Discussionmentioning

confidence: 99%

β-Galactosyl Yariv Reagent Binds to the β-1,3-Galactan of Arabinogalactan Proteins

et al. 2013

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Yariv phenylglycosides [1,3,5-tri(p-glycosyloxyphenylazo)-2,4,6-trihydroxybenzene] are a group of chemical compounds that selectively bind to arabinogalactan proteins (AGPs), a type of plant proteoglycan. Yariv phenylglycosides are widely used as cytochemical reagents to perturb the molecular functions of AGPs as well as for the detection, quantification, purification, and staining of AGPs. However, the target structure in AGPs to which Yariv phenylglycosides bind has not been determined. Here, we identify the structural element of AGPs required for the interaction with Yariv phenylglycosides by stepwise trimming of the arabinogalactan moieties using combinations of specific glycoside hydrolases. Whereas the precipitation with Yariv phenylglycosides (Yariv reactivity) of radish (Raphanus sativus) root AGP was not reduced after enzyme treatment to remove a-L-arabinofuranosyl and b-glucuronosyl residues and b-1,6-galactan side chains, it was completely lost after degradation of the b-1,3-galactan main chains. In addition, Yariv reactivity of gum arabic, a commercial product of acacia (Acacia senegal) AGPs, increased rather than decreased during the repeated degradation of b-1,6-galactan side chains by Smith degradation. Among various oligosaccharides corresponding to partial structures of AGPs, b-1,3-galactooligosaccharides longer than b-1,3-galactoheptaose exhibited significant precipitation with Yariv in a radial diffusion assay on agar. A pull-down assay using oligosaccharides cross linked to hydrazine beads detected an interaction of b-1,3-galactooligosaccharides longer than b-1,3-galactopentaose with Yariv phenylglycoside. To the contrary, no interaction with Yariv was detected for b-1,6-galactooligosaccharides of any length. Therefore, we conclude that Yariv phenylglycosides should be considered specific binding reagents for b-1,3-galactan chains longer than five residues, and seven residues are sufficient for cross linking, leading to precipitation of the Yariv phenylglycosides.Arabinogalactan proteins (AGPs) are a type of plant proteoglycans consisting of a Hyp-rich core protein and large arabinogalactan (AG) moieties (Fincher et al., 1983;Nothnagel, 1997). Although there are many molecular species of AGP differentiated by their core proteins, the AG moieties commonly comprise b-1,3-galactan main chains and b-1,6-galactan side chains, to which L-Ara and other auxiliary sugars, such as GlcA, 4-O-methyl-GlcA, L-Fuc, L-Rha, and Xyl, are attached (Fincher et al., 1983;Nothnagel, 1997;Seifert and Roberts, 2007). A commercial product of AGPs prepared from the acacia (Acacia senegal) tree is known as gum arabic and utilized as a food stabilizer. In the Japanese herbal remedy Juzen-Taiho-To, AGs from Astragalus membranaceus are the active ingredient (Majewska-Sawka and Nothnagel, 2000;Kiyohara et al., 2002). In intact plants, AGPs are implicated in various physiological events and serve as extracellular constituents and signaling molecules. For instance, an AGP from stylar transmitting tissue attracts pollen tub...

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“…The AGPs that have been most often investigated at the chemical structural level are those that are found in the medium of cultured cells and in plant exudates such as gums and mucilages (Akiyama et al, 1984;Bacic et al, 1987;Cartier et al, 1987;Komalavilas et al, 1991). These investigations have revealed that AGPs contain a galactan framework having p-(1,3)-, (1,6)-, and (1,3,6)-linkages (Fincher et al, 1983;Bacic et al, 1987;Cartier et al, 1987;Tsumuraya et al, 1988;Komalavilas et al, 1991;Saulnier et al, 1992).…”

mentioning

confidence: 99%

“…These investigations have revealed that AGPs contain a galactan framework having p-(1,3)-, (1,6)-, and (1,3,6)-linkages (Fincher et al, 1983;Bacic et al, 1987;Cartier et al, 1987;Tsumuraya et al, 1988;Komalavilas et al, 1991;Saulnier et al, 1992). Ara and lesser amounts of other sugars such as glucuronic acid and Rha are attached to the galactan frame-Plant Physiol.…”

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confidence: 99%

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Fractionation and Structural Characterization of Arabinogalactan-Proteins from the Cell Wall of Rose Cells

Serpe¹,

Nothnagel²

1995

Plant Physiol.

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Arabinogalactan-proteins (ACPs) have been purified from Paul's Scarlet rose (Rosa sp.) cell walls. As estimated by gel permeation chromatography, the apparent molecular masses of the two major cell-wall ACP fractions were 130 and 242 kD. Since the 130-kD ACP had a ratio of arabinose/glucuronic acid that was 12 times higher than that of the 242-kD ACP, the fractions were named cell-wall ACPl (CW-ACP1) and glucuronogalactan-protein (CCP), respectively. CW-AGP1 and CCP contained predominantly farabinofuranosyl residues; Ninked, 6-linked, and 3,6-branched galactopyranosyl residues; and 4-linked and t-glucuronopyranosyl residues. The 'H-nuclear magnetic resonance spectra of CW-ACP1 and CCP showed that the arabinofuranosyl and galactopyranosyl residues were predominantly in a-and p-anomeric configuration, respectively, and that GCP contained a few O-acetyl residues. The protein moieties of CW-ACP1 and CCP were both rich in hydroxyproline and alanine but differed in the percentage of various amino acids, including hydroxyproline, alanine, serine, and glycine. Cell-wall AGPs bound to (/3-D-glucosyl), Yariv phenylglycoside, but the stoichiometry of binding was about 6 times greater in CCP than in other Rosa ACPs. CCP seems to be peculiar to the cell wall, since no similar molecule was found in the culture medium.

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Fine structure of the arabinogalactan-protein from Lolium multiflorum

Cited by 53 publications

References 29 publications

Plant O-Hydroxyproline Arabinogalactans Are Composed of Repeating Trigalactosyl Subunits with Short Bifurcated Side Chains

Plant O-Hydroxyproline Arabinogalactans Are Composed of Repeating Trigalactosyl Subunits with Short Bifurcated Side Chains

β-Galactosyl Yariv Reagent Binds to the β-1,3-Galactan of Arabinogalactan Proteins

Fractionation and Structural Characterization of Arabinogalactan-Proteins from the Cell Wall of Rose Cells

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