Báo cáo khoa học: A kinetic model of the branch-point between the methionine and threonine biosynthesis pathways in Arabidopsis thaliana

A Kinetic Model of the Branch-Point Between the Methionine and Threonine Biosynthesis Pathways in Arabidopsis thaliana

Authors: Gilles Curien, Stéphane Ravanel, and Renaud Dumas

Field: Plant Physiology/Biochemistry

Document Content: This study proposes and validates a mathematical model for the metabolic branch-point between methionine and threonine biosynthesis in Arabidopsis thaliana. The model integrates kinetic competition for phosphohomoserine between the allosteric threonine synthase and the two-substrate cystathionine γ-synthase. It incorporates enzyme kinetics, operating conditions in chloroplasts, and experimental validation using purified enzymes. The research investigates the sensitivity of flux distribution to various factors, including S-adenosylmethionine, inorganic phosphate, cysteine, and enzyme concentrations, providing insights into the control mechanisms of amino acid synthesis in plants.

Detailed Table of Contents:

• Introduction
• Materials and Methods
• Modelling procedure
• Reconstitution of the branch-point
• Results
• Validation of the computer model
• Improvement of the computer model
• AMP inhibition does not affect partition
• Consistency with data collected in planta
• Sensitivity analysis
• Comparison of CGS and TS kinetic efficiencies under physiological operating conditions
• Consequences of CGS ping-pong kinetic mechanism on the branch-point kinetic properties
• Time-constant of the branch-point system
• Discussion
• Acknowledgements
• References