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Thioredoxin-mediated reversible dissociation of a stromal multiprotein complex in response to changes in light availability

Howard, TP and Metodiev, M and Lloyd, JC and Raines, CA (2008) 'Thioredoxin-mediated reversible dissociation of a stromal multiprotein complex in response to changes in light availability.' Proceedings of the National Academy of Sciences of the United States of America, 105 (10). 4056 - 4061. ISSN 0027-8424

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A Calvin cycle multiprotein complex including phosphoribulokinase (PRK), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and a small protein, CP12, has previously been identified. In this article, we have studied this complex in leaves and have shown that dissociation and reassociation of the PRK/GAPDH/CP12 complex occurs in a time frame of minutes, allowing for rapid regulation of enzyme activity. Furthermore, we have shown that the extent of formation and dissociation of the PRK/GAPDH/CP12 complex correlates with the quantity of light. These data provide evidence linking the status of this complex with the rapid and subtle regulation of GAPDH and PRK activities in response to fluctuations in light availability. We have also demonstrated that dissociation of this complex depends on electron transport chain activity and that the major factor involved in the dissociation of the pea complex was thioredoxin f. We show here that both PRK and GAPDH are present in the reduced form in leaves in the dark, but are inactive, demonstrating the role of the PRK/GAPDH/CP12 complex in deactivating these enzymes in response to reductions in light intensity. Based on our data, we propose a model for thioredoxin f-mediated activation of PRK and GAPDH by two mechanisms: directly through reduction of disulfide bonds within these enzymes and indirectly by mediating the breakdown of the complex in response to changes in light intensity. © 2008 by The National Academy of Sciences of the USA.

Item Type: Article
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 06 Oct 2011 12:00
Last Modified: 19 Aug 2019 16:15

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