Xyloglucan biosynthesis by Golgi membranes from suspension-cultured sycamore (Acer pseudoplatanus) cells

Conference · Tue May 01 00:00:00 EDT 1990 · Plant Physiology, Supplement; (USA)

OSTI ID:5725649

White, A R; Xin, Yi ^[1]

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1. North Dakota State Univ., Fargo (USA)

Xyloglucan is a major hemicellulose polysaccharide in plant cell walls. Biosynthesis of such cell wall polysaccharides is closely linked to the process of plant cell growth and development. Xyloglucan polysaccharides consist of a {beta}-1,4 glucan backbone synthesized by xyloglucan synthase and sidechains of xylose, galactose, and fucose added by other transferase enzymes. Most plant Golgi and plasma membranes also contain glucan synthases I II, which make {beta}-1,4 and {beta}-1,3 glucans, respectively. All of these enzymes have very similar activities. Cell walls on suspension-cultured cells from Acer pseudoplatanus (sycamore maple) were enzymatically softened prior to cell disruption by passing through a 30 {mu}m nylon screen. Cell membranes from homogenates were separated by ultracentrifugation on top-loaded or flotation sucrose density gradients. Samples were collected by gradient fractionation and assayed for membrane markers and xyloglucan and glucan synthase activities. Standard marker assays (cyt. c reductase for eR, IDPase UDPase for Golgi, and eosin 5{prime}-malelmide binding for plasma membrane) showed partial separation of these three membrane types. Golgi and plasma membrane markers overlapped in most gradients. Incorporation of {sup 14}C-labeled sugars from UDP-glucose and UDP-xylose was used to detect xyloglucan synthase, glucan synthases I II, and xylosyl transferase in Golgi membrane fractions. These activities overlapped, although distinct peaks of xyloglucan synthase and xylosyl transferase were found. Ca{sup ++} had a stimulatory effect on glucan synthases I II, while Mn{sup ++} had an inhibitory effect on glucan synthase I in the presence of Ca{sup ++}. The similarity of these various synthase activities demonstrates the need for careful structural characterization of newly synthesized polysaccharides.

• OSTI ID: 5725649
• Report Number(s): CONF-9007196-; CODEN: PPYSA
• Journal Information: Plant Physiology, Supplement; (USA), Vol. 93:1; Conference: Annual meeting of the American Society of Plant Physiologists, Indianapolis, IN (USA), 29 Jul - 2 Aug 1990; ISSN 0079-2241
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
POLYSACCHARIDES
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CELL CULTURES
CELL WALL
ORGANOIDS
SYCAMORES
TRACER TECHNIQUES
CARBOHYDRATES
CELL CONSTITUENTS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
MAGNOLIOPHYTA
MAGNOLIOPSIDA
ORGANIC COMPOUNDS
PLANTS
REACTION KINETICS
SACCHARIDES
TREES
550201* - Biochemistry- Tracer Techniques