Abstract
Here, we identify Arabidopsis thaliana Lumen Thiol Oxidoreductase1 (LTO1) as a disulfide bond-forming enzyme in the thylakoid lumen. Using topological reporters in bacteria, we deduced a lumenal location for the redox active domains of the protein. LTO1 can partially substitute for the proteins catalyzing disulfide bond formation in the bacterial periplasm, which is topologically equivalent to the plastid lumen. An insertional mutation within the LTO1 promoter is associated with a severe photoautotrophic growth defect. Measurements of the photosynthetic activity indicate that the lto1 mutant displays a limitation in the electron flow from photosystem II (PSII). In accordance with these measurements, we noted a severe depletion of the structural subunits of PSII but no change in the accumulation of the cytochrome b(6)f complex or photosystem I. In a yeast two-hybrid assay, the thioredoxin-like domain of LTO1 interacts with PsbO, a lumenal PSII subunit known to be disulfide bonded, and a recombinant form of the molecule can introduce a disulfide bond in PsbO in vitro. The documentation of a sulfhydryl-oxidizing activity in the thylakoid lumen further underscores the importance of catalyzed thiol-disulfide chemistry for the biogenesis of the thylakoid compartment.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Arabidopsis / drug effects
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Arabidopsis / enzymology*
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Arabidopsis / physiology
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism
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Base Sequence
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Cloning, Molecular
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Cytochromes f / metabolism
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DNA, Plant / genetics
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DNA, Plant / metabolism
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Disulfides / metabolism
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Enzyme Activation
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Genetic Complementation Test
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Genetic Vectors / genetics
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Genetic Vectors / metabolism
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Molecular Sequence Data
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Oxidation-Reduction
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Photosynthesis
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Photosystem II Protein Complex / genetics
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Photosystem II Protein Complex / metabolism*
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Plant Leaves / drug effects
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Plant Leaves / genetics
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Plant Leaves / metabolism
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Plasmids / genetics
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Plasmids / metabolism
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Promoter Regions, Genetic
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Protein Interaction Domains and Motifs
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Thylakoid Membrane Proteins / genetics
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Thylakoid Membrane Proteins / metabolism
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Thylakoids / enzymology*
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Thylakoids / metabolism
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Transformation, Genetic
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Two-Hybrid System Techniques
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Vitamin K Epoxide Reductases / genetics
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Vitamin K Epoxide Reductases / metabolism*
Substances
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Arabidopsis Proteins
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Bacterial Proteins
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DNA, Plant
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Disulfides
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Photosystem II Protein Complex
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Thylakoid Membrane Proteins
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photosystem II manganese-stabilizing protein
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Cytochromes f
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Vitamin K Epoxide Reductases
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lumen thiol oxidoreductase 1, Arabidopsis
Associated data
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GENBANK/AAM65737
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GENBANK/ACN43307
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GENBANK/ACN43308