A Role for Chlorophyllide a Oxygenase in the Regulated Import and Stabilization of Light-Harvesting Chlorophyll a/b Proteins

The Arabidopsis CAO gene encodes a 52-kDa protein with predicted localization in the plastid compartment. Here, we report that CAO is an intrinsic Rieske iron-sulfur protein of the plastidenvelope inner and thylakoid membranes. Activity measurements revealed that CAO catalyzes chlorophyllide a to ch...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2006-03, Vol.103 (12), p.4777-4782
Main Authors: Reinbothe, Christiane, Bartsch, Sandra, Eggink, Laura L., Hoober, J. Kenneth, Brusslan, Judy, Andrade-Paz, Ricardo, Monnet, Julie, Reinbothe, Steffen
Format: Article
Language:English
Subjects:
Arabidopsis
Arabidopsis - enzymology
Arabidopsis - genetics
Barley
Biochemistry, Molecular Biology
Biological Sciences
Chlorophyll
Chlorophyllides
Chlorophyllides - metabolism
Chlorophylls
Chloroplasts
Crosslinking
Electron Transport Complex III - genetics
Electron Transport Complex III - metabolism
Enzyme Stability
Enzymes
Flowers & plants
Genes
Imports
Iron-Sulfur Proteins - genetics
Iron-Sulfur Proteins - metabolism
Life Sciences
Light-Harvesting Protein Complexes - metabolism
Oxygenases - genetics
Oxygenases - metabolism
P branes
Photosystem II Protein Complex - metabolism
Pigments
Plastids
Protein Kinases - metabolism
Protein precursors
Protein Transport
Proteins
Thylakoids - enzymology
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Summary:The Arabidopsis CAO gene encodes a 52-kDa protein with predicted localization in the plastid compartment. Here, we report that CAO is an intrinsic Rieske iron-sulfur protein of the plastidenvelope inner and thylakoid membranes. Activity measurements revealed that CAO catalyzes chlorophyllide a to chlorophyllide b conversion in vitro and that the enzyme was only slightly active with protochlorophyllide a, the nonreduced precursor of chlorophyllide a. Protein import and organelle fractionation studies identified CAO to be distinct from Ptc52 in the substrate-dependent transport pathway of NADPH:protochlorophyllide oxidoreductase A but instead to be part of a separate translocon complex. This complex was involved in the regulated import and stabilization of the chlorophyllide b-binding light-harvesting proteins Lhcbl (LHCII) and Lhcb4 (CP29) in chloroplasts. Together, our results provide insights into the plastid subcompartmentalization and evolution of chlorophyll precursor biosynthesis in relation to protein import in higher plants.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0511066103