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          Institute: MPI für molekulare Pflanzenphysiologie     Collection: Publikationen Pflanzenphysiologie     Display Documents

ID: 251461.0, MPI für molekulare Pflanzenphysiologie / Publikationen Pflanzenphysiologie
Redox regulation of carbon storage and partitioning in response to light and sugars
Authors:Geigenberger, P.; Kolbe, A.; Tiessen, A.
Date of Publication (YYYY-MM-DD):2005-06
Title of Journal:Journal of Experimental Botany
Journal Abbrev.:J Exp Bot
Issue / Number:416
Start Page:1469
End Page:1479
Review Status:not specified
Audience:Not Specified
Abstract / Description:Redox signals generated by the photosynthetic electron transport chain are known to be involved in regulating the Calvin cycle, ATP synthesis, and NADPH export from chloroplasts in response to light. The signal cascade involves transfer of electrons from photosystem I via the ferredoxin-thioredoxin system to target enzymes that are activated by reduction of regulatory disulphide bonds. The purpose of this review is to discuss recent findings showing that this concept can be extended to the regulation of carbon storage and partitioning in plants. Starch is the major carbon store in plants, and ADP-glucose pyrophosphorylase (AGPase) is the key regulatory enzyme of starch synthesis in the plastid. It has been shown that AGPase from potato tubers is subject to post-translational redox modification, and here experimental data will be provided showing that the isozyme from pea leaf chloroplasts is activated by reduced thioredoxin f or m in a similar way. Recent reports will be summarized providing in planta evidence that this mechanism regulates storage starch synthesis in response to light and sugars. Post-translational redox activation of AGPase in response to sugars is part of a signalling mechanism linking the rate of starch synthesis to the availability of carbon in diverse plant tissues. Some of the components of the signalling pathway reporting changes in the cytosolic sugar status to the plastid have been postulated, but detailed work is in progress to confirm the exact mode of action. Recent evidence will be discussed showing that key enzymes of de novo fatty acid synthesis (acetyl-CoA carboxylase) and ammonium assimilation (glutamine synthetase and glutamine:oxoglutarate amino transferase) are regulated by reversible disulphide-bond formation similar to AGPase. Redox regulation is proposed to be the preferred strategy of plastidial enzymes to regulate various metabolic processes such as carbon fixation, starch metabolism, lipid synthesis, and amino acid synthesis in response to physiological and environmental inputs.
Free Keywords:acetyl-coa carboxylase
; adp-glucose pyrophosphorylase
; amino acids
; arabidopsis
; lipids
; potato (tuber)
; redox (regulation)
; signalling (snf1)
; starch
; sucrose
; thioredoxin
; adp-glucose pyrophosphorylase
; acetyl-coa carboxylase
; fatty-acid synthesis
; growing potato-tubers
; starch synthesis
; solanum-tuberosum
; r1 protein
; chlamydomonas-reinhardtii
; carbohydrate utilization
; reductive activation
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für molekulare Pflanzenphysiologie/Metabolische Netzwerke/AG Geigenberger
External Affiliations:Max Planck Inst Mol Plant Physiol, Muhlenberg 1, D-14476 Golm, Germany
Max Planck Inst Mol Plant Physiol, D-14476 Golm, Germany
Identifiers:ISI:000229285900005 [ID No:1]
ISI:000229285900005 [ID No:2]
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