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Updated: Aug 11, 2026
12:07
Profiling Thiol Redox Proteome Using Isotope Tagging Mass Spectrometry
Published on: March 24, 2012
A complete ferredoxin/thioredoxin system regulates fundamental processes in amyloplasts
Yves Balmer1, William H Vensel, Nick Cai
1Department of Plant and Biology, University of California, 111 Koshland Hall, Berkeley, CA 94720, USA.
Summary
Plant amyloplasts utilize the ferredoxin/thioredoxin (Trx) system for redox regulation, impacting starch synthesis and other metabolic pathways. This discovery reveals a novel link between photosynthesis and sink tissue metabolism through thiol signaling.
Area of Science:
- Plant biochemistry and molecular biology
- Redox regulation in plant organelles
- Photosynthesis and carbon metabolism
Background:
- Thiol-disulfide exchange mediated by thioredoxin (Trx) regulates numerous biological processes.
- Trx system components (ferredoxin, ferredoxin-Trx reductase, Trx) are well-characterized in chloroplasts.
- Amyloplasts are key organelles in plant heterotrophic tissues for starch synthesis and storage.
Purpose of the Study:
- To investigate the presence and function of the ferredoxin/Trx system in plant amyloplasts.
- To identify Trx targets within amyloplasts and elucidate their roles in metabolism.
- To understand how amyloplast function is coordinated with photosynthesis in leaves.
Main Methods:
- Proteomics and immunological techniques to identify ferredoxin/Trx system components in isolated wheat endosperm amyloplasts.
- Affinity chromatography and fluorescent thiol probes to identify Trx target proteins.
- Analysis of ferredoxin reduction pathways, distinguishing light-dependent (chloroplast) from metabolic (amyloplast) sources.
Main Results:
- The ferredoxin/Trx system, including ferredoxin, ferredoxin-Trx reductase, and m-type Trx, was identified in wheat endosperm amyloplasts.
- Ferredoxin in amyloplasts is reduced by NADPH via ferredoxin-NADP reductase, not by light.
- 42 potential Trx targets were identified, including 13 novel proteins like the ADP-glucose transporter (Brittle-1), involved in starch, lipid, amino acid, and nucleotide biosynthesis.
Conclusions:
- Plant amyloplasts possess a functional ferredoxin/Trx system regulated by metabolic NADPH.
- Trx targets in amyloplasts indicate its broad regulatory role beyond starch metabolism, encompassing various biosynthetic pathways.
- This redox signaling pathway provides a mechanism to coordinate sink metabolism (amyloplasts) with source activity (photosynthesis).
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