Abstract
Wild watermelon (Citrullus lanatus sp.) has the ability to tolerate severe drought/high light stress conditions despite carrying out normal C3-type photosynthesis. Here, mRNA differential display was employed to isolate drought-responsive genes in the leaves of wild watermelon. One of the isolated genes, CLMT2, shared significant homology with type-2 metallothionein (MT) sequences from other plants. The second-order rate constant for the reaction between a recombinant CLMT2 protein and hydroxyl radicals was estimated to be 1.2 x 10(11) M(-1) s(-1), demonstrating that CLMT2 had an extraordinary high activity for detoxifying hydroxyl radicals. Moreover, hydroxyl radical-catalyzed degradation of watermelon genomic DNA was effectively suppressed by CLMT2 in vitro. This is the first demonstration of a plant MT with antioxidant properties. The results suggest that CLMT2 induction contributes to the survival of wild watermelon under severe drought/high light stress conditions.
Copyright 2004 Elsevier Inc.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Arabidopsis Proteins / chemistry*
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Arabidopsis Proteins / metabolism
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Catalysis
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Citrullus
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Cloning, Molecular
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DNA / chemistry
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DNA, Complementary / metabolism
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Disasters
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Dose-Response Relationship, Drug
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Gene Expression Profiling
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Hydroxyl Radical* / chemistry
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Metallothionein / chemistry*
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Metallothionein / metabolism
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Molecular Sequence Data
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Oxidative Stress
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Phylogeny
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Plant Proteins / chemistry
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RNA / chemistry
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RNA, Messenger / metabolism
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Recombinant Proteins / chemistry
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Sequence Homology, Amino Acid
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Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
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Time Factors
Substances
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Arabidopsis Proteins
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DNA, Complementary
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MT2A protein, Arabidopsis
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Plant Proteins
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RNA, Messenger
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Recombinant Proteins
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Hydroxyl Radical
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RNA
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DNA
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Metallothionein
Associated data
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GENBANK/AB182918
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GENBANK/AB182919
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GENBANK/AB182920
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GENBANK/AB182921
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GENBANK/AB182922
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GENBANK/AB182923
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GENBANK/AB182924
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GENBANK/AB182925
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GENBANK/AB182926
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GENBANK/AB182927
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GENBANK/AB182928
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GENBANK/AB182929
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GENBANK/AB182930
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GENBANK/AB182931
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GENBANK/AB182932
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GENBANK/AB182933
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GENBANK/AB182934
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GENBANK/AB182935
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GENBANK/AB182936
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GENBANK/AB182937
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GENBANK/AB182938