Mitochondrial uncoupling protein is required for efficient photosynthesis

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 103; no. 51; pp. 19587 - 19592
• Main Authors: Sweetlove, L.J, Lytovchenko, A, Morgan, M, Nunes-Nesi, A, Taylor, N.L, Baxter, C.J, Eickmeier, I, Fernie, A.R
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 19.12.2006; National Acad Sciences
• Subjects: amino acid metabolism; Arabidopsis; Arabidopsis - genetics; Arabidopsis - physiology; Arabidopsis thaliana; Biological Sciences; Blotting, Western; Carbon - metabolism; DNA Primers; Electrons; Flowers & plants; Genes; glycine (amino acid); Glycine - metabolism; Ion Channels - metabolism; Leaves; membrane proteins; Mitochondria; Mitochondria - metabolism; Mitochondrial Proteins - metabolism; mitochondrial uncoupling proteins; mutants; Oxidation; Oxidative stress; Oxidative Stress - genetics; phenotype; Photorespiration; Photosynthesis; Photosynthesis - genetics; Photosynthesis - physiology; Plant Leaves - genetics; Plant Leaves - physiology; Plant mitochondria; plant proteins; Plants; Proteins; Protons; Reactive oxygen species; Reverse Transcriptase Polymerase Chain Reaction; Uncoupling Protein 1
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0607751103

Uncoupling proteins (UCPs) occur in the inner mitochondrial membrane and dissipate the proton gradient across this membrane that is normally used for ATP synthesis. Although the catalytic function and regulation of plant UCPs have been described, the physiological purpose of UCP in plants has not been established. Here, biochemical and physiological analyses of an insertional knockout of one of the Arabidopsis UCP genes (AtUCP1) are presented that resolve this issue. Absence of UCP1 results in localized oxidative stress but does not impair the ability of the plant to withstand a wide range of abiotic stresses. However, absence of UCP1 results in a photosynthetic phenotype. Specifically there is a restriction in photorespiration with a decrease in the rate of oxidation of photorespiratory glycine in the mitochondrion. This change leads to an associated reduced photosynthetic carbon assimilation rate. Collectively, these results suggest that the main physiological role of UCP1 in Arabidopsis leaves is related to maintaining the redox poise of the mitochondrial electron transport chain to facilitate photosynthetic metabolism.