| Posttranslational redox modification of ADP-glucose pyrophosphorylase in response to light is not a major determinant of fine regulation of transitory starch accumulation in Arabidopsis leaves. | |
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MedLine Citation:
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PMID: 22210900 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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ADP-glucose pyrophosphorylase (AGP) is a heterotetrameric enzyme comprising two small and two large subunits that catalyze the production of ADP-glucose linked to starch biosynthesis. The current paradigm on leaf starch metabolism assumes that posttranslational redox modification of AGP in response to light is a major determinant of fine regulation of transitory starch accumulation. According to this view, under oxidizing conditions occurring during the night the two AGP small subunits (APS1) are covalently linked via an intermolecular disulfide bridge that inactivates the protein, whereas under reducing conditions occurring during the day NADP-thioredoxin reductase C (NTRC)-dependent reductive monomerization of APS1 activates the enzyme. In this work we have analyzed changes in the redox status of APS1 during dark/light transition in leaves of plants cultured under different light intensities. Furthermore, we have carried out time-course analyses of starch content in ntrc mutants, and in aps1 mutants expressing in the chloroplast the Escherichia coli redox insensitive AGP (GlgC). We also characterized aps1 plants expressing a redox insensitive, mutated APS1 (APS1mut) form in which the highly conserved Cys(81) residue involved in the formation of intermolecular disulfide bridge has been replaced by Ser. We found that a moderate, NTRC-dependent APS1 monomerization process in response to light occurred only when plants were cultured under photo-oxidative conditions. We also found that starch accumulation rates during the light in leaves of both ntrc mutants and GlgC-expressing aps1 mutants were similar to those of wild-type leaves. Furthermore, the pattern of starch accumulation during illumination in leaves of APS1mut- expressing aps1 mutants was similar to that of APS1- expressing aps1 mutants at any light intensity. The overall data demonstrate that posttranslational redox modification of AGP in response to light is not a major determinant of fine regulation of transitory starch accumulation in Arabidopsis. |
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Authors:
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Jun Li; Goizeder Almagro; Francisco José Muñoz; Edurne Baroja-Fernández; Abdellatif Bahaji; Manuel Montero; Maite Hidalgo; Angela María Sánchez-López; Ignacio Ezquer; María Teresa Sesma; Javier Pozueta-Romero |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-12-30 |
Journal Detail:
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Title: Plant & cell physiology Volume: - ISSN: 1471-9053 ISO Abbreviation: - Publication Date: 2011 Dec |
Date Detail:
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Created Date: 2012-1-2 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9430925 Medline TA: Plant Cell Physiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Affiliation:
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(1) Instituto de Agrobiotecnología (CSIC/UPNA/Gobierno de Navarra). Mutiloako etorbidea z/g, 31192 Mutiloa, Nafarroa, Spain. |
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