Knock-down of the COX3 and COX17 gene expression of cytochrome c oxidase in the unicellular green alga Chlamydomonas reinhardtii

Knock-down of the COX3 and COX17 gene expression of cytochrome c oxidase in the unicellular green... The COX3 gene encodes a core subunit of mitochondrial cytochrome c oxidase (complex IV) whereas the COX17 gene encodes a chaperone delivering copper to the enzyme. Mutants of these two genes were isolated by RNA interference in the microalga Chlamydomonas. The COX3 mRNA was completely lacking in the cox3-RNAi mutant and no activity and assembly of complex IV were detected. The cox17-RNAi mutant presented a reduced level of COX17 mRNA, a reduced activity of the cytochrome c oxidase but no modification of its amount. The cox3-RNAi mutant had only 40% of the wild-type rate of dark respiration which was cyanide-insensitive. The mutant presented a 60% decrease of H2O2 production in the dark compared to wild type, which probably accounts for a reduced electron leakage by respiratory complexes III and IV. In contrast, the cox17-RNAi mutant showed no modification of respiration and of H2O2 production in the dark but a two to threefold increase of H2O2 in the light compared to wild type and the cox3-RNAi mutant. The cox17-RNAi mutant was more sensitive to cadmium than the wild-type and cox3-RNAi strains. This suggested that besides its role in complex IV assembly, Cox17 could have additional functions in the cell such as metal detoxification or Reactive Oxygen Species protection or signaling. Concerning Cox3, its role in Chlamydomonas complex IV is similar to that of other eukaryotes although this subunit is encoded in the nuclear genome in the alga contrary to the situation found in all other organisms. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Molecular Biology Springer Journals

Knock-down of the COX3 and COX17 gene expression of cytochrome c oxidase in the unicellular green alga Chlamydomonas reinhardtii

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Publisher
Springer Netherlands
Copyright
Copyright © 2010 by Springer Science+Business Media B.V.
Subject
Life Sciences; Plant Pathology; Biochemistry, general; Plant Sciences
ISSN
0167-4412
eISSN
1573-5028
D.O.I.
10.1007/s11103-010-9668-6
Publisher site
See Article on Publisher Site

Abstract

The COX3 gene encodes a core subunit of mitochondrial cytochrome c oxidase (complex IV) whereas the COX17 gene encodes a chaperone delivering copper to the enzyme. Mutants of these two genes were isolated by RNA interference in the microalga Chlamydomonas. The COX3 mRNA was completely lacking in the cox3-RNAi mutant and no activity and assembly of complex IV were detected. The cox17-RNAi mutant presented a reduced level of COX17 mRNA, a reduced activity of the cytochrome c oxidase but no modification of its amount. The cox3-RNAi mutant had only 40% of the wild-type rate of dark respiration which was cyanide-insensitive. The mutant presented a 60% decrease of H2O2 production in the dark compared to wild type, which probably accounts for a reduced electron leakage by respiratory complexes III and IV. In contrast, the cox17-RNAi mutant showed no modification of respiration and of H2O2 production in the dark but a two to threefold increase of H2O2 in the light compared to wild type and the cox3-RNAi mutant. The cox17-RNAi mutant was more sensitive to cadmium than the wild-type and cox3-RNAi strains. This suggested that besides its role in complex IV assembly, Cox17 could have additional functions in the cell such as metal detoxification or Reactive Oxygen Species protection or signaling. Concerning Cox3, its role in Chlamydomonas complex IV is similar to that of other eukaryotes although this subunit is encoded in the nuclear genome in the alga contrary to the situation found in all other organisms.

Journal

Plant Molecular BiologySpringer Journals

Published: Aug 11, 2010

References

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