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A metabolic flux analysis to study the role of sucrose synthase in the regulation of the carbon partitioning in central metabolism in maize root tips ☆

Paper ID Volume ID Publish Year Pages File Format Full-Text
31940 44857 2007 14 PDF Available
Title
A metabolic flux analysis to study the role of sucrose synthase in the regulation of the carbon partitioning in central metabolism in maize root tips ☆
Abstract

In order to understand the role of sucrose synthase (SuSy) in carbon partitioning, metabolic fluxes were analyzed in maize root tips of a double mutant of SuSy genes, sh1 sus1 and the corresponding wild type, W22. [U-14C]-glucose pulse labeling experiments permitted the quantification of unidirectional fluxes into sucrose, starch and cell wall polysaccharides. Isotopic steady-state labeling with [1-13C]-, [2-13C]- or [U-13C]-glucose followed by the quantification by 1H-NMR and 13C-NMR of enrichments in carbohydrates and amino acids was also performed to determine 29 fluxes through central metabolism using computer-aided modeling. As a consequence of the suppression of SUS1 and SH1 isozymes, maize root tips diameter was significantly decreased and respiratory metabolism reduced by 30%. Our result clearly established that, in maize root tips, starch is produced from ADP-Glc synthesized in the plastid and not in the cytosol by sucrose synthase. Unexpectedly, the flux of cell wall synthesis was increased in the double mutant. This observation indicates that, in maize root tips, SH1 and SUS1 are not specific providers for cellulose biosynthesis.

Keywords
Sucrose synthase; Metabolic flux analysis; Cell wall; Maize root; Isotopic labeling; NMR
First Page Preview
A metabolic flux analysis to study the role of sucrose synthase in the regulation of the carbon partitioning in central metabolism in maize root tips ☆
Publisher
Database: Elsevier - ScienceDirect
Journal: Metabolic Engineering - Volume 9, Issues 5–6, September–November 2007, Pages 419–432
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering