Copper Delivery by the Copper Chaperone for Chloroplast and Cytosolic Copper/Zinc- Superoxide Dismutases： Regulation and Unexpected Phenotypes in an Arabidopsis Mutant

Copper (Cu) is an important mineral nutrient found in chloroplasts as a cofactor associated with plastocyanin and Cu/Zn superoxide dismutase (Cu/ZnSOD). Superoxide dismutases are metallo-enzymes found in most oxygenic organisms with proposed roles in reducing oxidative stress. Several recent studies...

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Bibliographic Details
Published in:	Molecular plant Vol. 2; no. 6; pp. 1336 - 1350
Main Authors:	Cohu, Christopher M., Abdel-Ghany, Salah E., Gogolin Reynolds, Kathryn A., Onofrio, Alexander M., Bodecker, Jared R., Kimbrel, Jeffrey A., Niyogi, Krishna K., Pilon, Marinus
Format:	Journal Article
Language:	English
Published:	England Elsevier Inc 01-11-2009 Oxford University Press
Subjects:	Arabidopsis - genetics Arabidopsis - metabolism Arabidopsis Proteins - genetics Arabidopsis Proteins - metabolism Base Sequence Chlorophyll - metabolism Chloroplast Chloroplasts - metabolism Copper - metabolism copper homeostasis Cytosol - metabolism microRNA MicroRNAs - genetics Mutation Phenotype photosynthesis Promoter Regions, Genetic RNA, Plant - genetics Sequence Alignment Sequence Homology, Nucleic Acid superoxide dismutase Superoxide Dismutase - metabolism 交付伴侣叶绿体拟南芥突变体胞质规例超氧化物歧化酶 microRNA photosynthesis copper homeostasis superoxide dismutase Chloroplast
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Summary:	Copper (Cu) is an important mineral nutrient found in chloroplasts as a cofactor associated with plastocyanin and Cu/Zn superoxide dismutase (Cu/ZnSOD). Superoxide dismutases are metallo-enzymes found in most oxygenic organisms with proposed roles in reducing oxidative stress. Several recent studies in Arabidopsis have shown that microRNAs and a SQUAMOSA promoter binding protein-like7 (SPL7) transcription factor function to down-regulate the expression of many Cu-proteins, including Cu/ZnSOD in both plastids and the cytosol, during growth on low Cu. Plants contain the Cu Chaperone for SOD (CCS) that delivers Cu to Cu/ZnSODs, and, in Arabidopsis, both cytosolic and plastidic CCS versions are encoded by one gene. In this study, we demonstrate that Arabidopsis CCS transcript levels are regulated by Cu, mediated by microRNA 398 that was not previously predicted to target CCS. The microRNA target site is conserved in CCS of Oryza sativa. The data suggest that Cu-regulated microRNAs may have more mRNA targets than was previously predicted. A CCS null mutant has no measurable SOD activity in the chloroplast and cytosol, indicating an absolute requirement for CCS. When the CCS null mutant was grown on high Cu media, it lacked both Fe superoxide dismutase (FeSOD) and Cu/ZnSOD activity. However, this did not lead to a visual phenotype and no photosynthetic deficiencies were detected, even after high light stress. These results indicate that Cu/ZnSOD is not a pivotal component of the photosynthetic anti-oxidant system during growth in laboratory conditions.
Bibliography:	31-2013/Q Q554.9 photosynthesis superoxide dismutase Q945.11 Chloroplast; photosynthesis; copper homeostasis; superoxide dismutase; microRNA. copper homeostasis Chloroplast microRNA. ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1674-2052 1752-9867
DOI:	10.1093/mp/ssp084