Poster: Late and Moved Abstracts
Abs #
942: A regulator of ethylene receptor function: a novel copper chaperone?
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Presenter: |
Jovanovic, Marko , maki_vienna@yahoo.com |
Authors | Jovanovic, Marko (A) Michiels, An (A) Resnick, Josephine S. (A) Hamza, Iqbal (B) Chang, Caren (A) | | Affiliations: |
(A): University of Maryland - College Park, Dept. of Cell Biology and Molecular Genetics
(B): University of Maryland, Dept. of Animal and Avian Science
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The ethylene receptors require copper (Cu) ions for high affinity ethylene binding. Moreover, Cu might be required for proper assembly of the receptors, as depleting the receptors of Cu by knocking out the Cu transporter RAN1 results in a constitutive ethylene-response phenotype resembling loss-of-function of multiple ethylene receptor genes. The Arabidopsis RTE1 (REVERSION-TO-ETHYLENE SENSITIVITY1) gene was identified in a screen for suppressors of the dominant etr1-2 mutation, which confers ethylene insensitivity. By knocking out RTE1, the insensitivity of the etr1-2 mutant reverts to wild type, and data suggests that this occurs due to loss of ETR1 function (which appears wild-type due to redundancy among the ethylene receptor family). The RTE1 gene is conserved in multicellular eukaryotes, but the function of RTE1 remains unknown. The RTE1 product has regions of highly conserved cysteines and histidines as found in metal-binding proteins. Thus one hypothesis is that RTE1 serves as a “Cu delivery protein”. As with ran1 mutants, knocking out RTE1 might make ETR1 non-functional due to a failure to deliver the necessary Cu cofactor to ETR1.
To test the possible involvement of Cu delivery to ETR1, four approaches have been initiated: 1) an Ethylene Binding Assay to test whether ethylene binding is enhanced in yeast cells coexpressing RTE1 and ETR1, 2) a Cu64 Binding Assay to test whether RTE1 enhances binding of Cu by ETR1, 3) Flame AA to measure the Cu content of yeast cells expressing RTE1 or RTE2, and 4) a Growth Test in yeast to look for significant changes in the growth of cells expressing RTE1 or RTE2 upon exposure to different metals and metal chelators. To date, we have no firm evidence that RTE1 can transport Cu or enhance the ability of ETR1 to bind ethylene.
