A Mutant Impaired in the Production of Plastome-Encoded Proteins Uncovers a Mechanism for the Homeostasis of Isoprenoid Biosynthetic Enzymes in<i>Arabidopsis</i>Plastids
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- Úrsula Flores-Pérez
- Departament de Genètica Molecular de Plantes, Centre for Research on Agricultural Genomics, 08034 Barcelona, Spain
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- Susanna Sauret-Güeto
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, 08028 Barcelona, Spain
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- Elisabet Gas
- Departament de Genètica Molecular de Plantes, Centre for Research on Agricultural Genomics, 08034 Barcelona, Spain
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- Paul Jarvis
- Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom
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- Manuel Rodríguez-Concepción
- Departament de Genètica Molecular de Plantes, Centre for Research on Agricultural Genomics, 08034 Barcelona, Spain
説明
<jats:title>Abstract</jats:title><jats:p>The plastid-localized methylerythritol phosphate (MEP) pathway synthesizes the isoprenoid precursors for the production of essential photosynthesis-related compounds and hormones. We have identified an Arabidopsis thaliana mutant, rif1, in which posttranscriptional upregulation of MEP pathway enzyme levels is caused by the loss of function of At3g47450, a gene originally reported to encode a mitochondrial protein related to nitric oxide synthesis. However, we show that nitric oxide is not involved in the regulation of the MEP pathway and that the encoded protein is a plastid-targeted homolog of the Bacillus subtilis YqeH protein, a GTPase required for proper ribosome assembly. Consistently, in rif1 seedlings, decreased levels of plastome-encoded proteins were observed, with the exception of ClpP1, a catalytic subunit of the plastidial Clp protease complex. The unexpected accumulation of ClpP1 in plastids with reduced protein synthesis suggested a compensatory mechanism in response to decreased Clp activity levels. In agreement, a negative correlation was found between Clp protease activity and MEP pathway enzyme levels in different experiments, suggesting that Clp-mediated degradation of MEP pathway enzymes might be a mechanism used by individual plastids to finely adjust plastidial isoprenoid biosynthesis to their functional and physiological states.</jats:p>
収録刊行物
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- The Plant Cell
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The Plant Cell 20 (5), 1303-1315, 2008-05-01
Oxford University Press (OUP)