A membrane-associated form of sucrose synthase and its potential role in synthesis of cellulose and callose in plants

Journal Article · Tue Sep 26 04:00:00 EDT 1995 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.92.20.9353· OSTI ID:120998

Amor, Y ^[1]; Haigler, C H; Johnson, S; Wainscott, M ^[2]

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1. Hebrew Univ. of Jerusalem (Israel)
2. Texas Tech Univ., Lubbock, TX (United States); and others

Sucrose synthase (SuSy;EC2,4,1.13; sucrose + UDP{rightleftharpoons}UDPglucose + fructose) has always been studied as a cytoplasmic enzyme in plant cells where it serves to degrade sucrose and provide carbon for respiration and synthesis of cell wall polysaccharides and starch. We report here that at least half of the total SuSy of developing cotton fibers (Gossypium hirsutum) is tightly associated with the plasma membrane. Therefore, this form of SuSy might serve to channel carbon directly from sucrose to cellulose and/or callose synthases in the plasma membrane. By using detached and permeabilized cotton fibers, we show that carbon from sucrose can be converted at high rates to both cellulose and callose. Synthesis of cellulose or callose is favored by addition of EGTA or calcium and cellobiose, respectively. These findings contrast with the traditional observation that when UDPglucose is used as substrate in vitro, callose is the major product synthesized. Immunolocalization studies how that SuSy can be localized at the fiber surface in patterns consistent with the deposition of cellulose or callose. Thus, these results support a model in which SuSy exists in a complex with the {beta}-glucan synthases and serves to channel carbon from sucrose to glucan.

• Sponsoring Organization: USDOE
• OSTI ID: 120998
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 20 Vol. 92; ISSN 0027-8424; ISSN PNASA6
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
BIOLOGICAL PATHWAYS
CELLULOSE
COTTON
PLANTS
SYNTHESIS