Knock-down of the COX3 and COX17 gene expression of cytochrome c oxidase in the unicellular green alga Chlamydomonas reinhardtii.
Remacle, Claire ; Coosemans, Nadine ; Jans, Frédéric et al
in Plant Molecular Biology (2010), 74(3), 223-2363
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 ... [more ▼]
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 H(2)O(2) 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 H(2)O(2) production in the dark but a two to threefold increase of H(2)O(2) 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. [less ▲]Detailed reference viewed: 40 (12 ULg)
Characterization of UDP-glucose : protein transglucosylase genes from potato.
; ; du Jardin, Patrick et al
in Plant Molecular Biology (2003), 52Detailed reference viewed: 4 (0 ULg)
Identification Of Cystosolic Mg2+-Dependent Soluble Inorganic Pyrophosphatases In Potato And Phylogenetic Analysis
; Dubois, Françoise ; et al
in Plant Molecular Biology (1999), 39(3),Detailed reference viewed: 19 (5 ULg)
Characterization of the potato mitochondrial transcription unit containing 'native' trnS (GCU), trnF (GAA) and trnP (UGG)
Remacle, Claire ;
in Plant Molecular Biology (1996), 30(3), 553-563
In order to identify the sequences promoting the expression of plant mitochondrial tRNA genes, we have characterized the trnS (GCU), trnF (GAA) and trnP (UGG) transcription unit of the potato ... [more ▼]
In order to identify the sequences promoting the expression of plant mitochondrial tRNA genes, we have characterized the trnS (GCU), trnF (GAA) and trnP (UGG) transcription unit of the potato mitochondrial genome. These three tRNA genes were shown to be co-transcribed as a 1800 nt long primary transcript. The transcription initiation site located 305 to 312 nt upstream of trnS is surrounded by a purine-rich region but does not contain the consensus motif proposed as a promoter element in dicotyledonous plants. Differential labelling of potato mitochondrial RNA with either guanylyltransferase or T4 polynucleotide kinase suggests that this site corresponds to the unique functional region responsible for the transcription of these three tRNA genes. The initiation site recently found upstream of Oenothera mitochondrial rr trnF does not seem to be used in potato mitochondria, although a very similar sequence is present 317 nt upstream of the corresponding potato gene. Major processing sites were identified at the 3' end of each tRNA gene. Another processing site, surrounded by a double hairpin structure, is located 498 nt downstream of trnP in stretch of 10 A residues. As judged from northern experiments, this region is close to the determination site of this transcription unit. [less ▲]Detailed reference viewed: 5 (0 ULg)
Biochemical, genetic and molecular characterization of new respiratory-deficient mutants in Chlamydomonas reinhardtii.
; ; et al
in Plant Molecular Biology (1992), 18
Eight respiratory-deficient mutants of Chlamydomonas reinhardtii have been isolated after mutagenic treatment with acriflavine or ethidium bromide. They are characterized by their inability to grow or ... [more ▼]
Eight respiratory-deficient mutants of Chlamydomonas reinhardtii have been isolated after mutagenic treatment with acriflavine or ethidium bromide. They are characterized by their inability to grow or their very reduced growth under heterotrophic conditions. One mutation (Class III) is of nuclear origin whereas the seven remaining mutants (Classes I and II) display a predominantly paternal mt- inheritance, typical of mutations residing in the mitochondrial DNA. Biochemical analysis has shown that all mutants are deficient in the cyanide-sensitive cytochrome pathway of the respiration whereas the alternative pathway is still functional. Measurements of complexes II + III (antimycin-sensitive succinate-cytochrome c oxido-reductase) and complex IV (cytochrome c oxidase) activities allowed to conclude that six mutations have to be localized in the mitochondrial apocytochrome b (COB) gene, one in the mitochondrial cytochrome oxidase subunit I (COI) gene and one in a nuclear gene encoding a component of the cytochrome oxidase complex. By using specific probes, we have moreover demonstrated that five mutants (Class II mutants) contain mitochondrial DNA molecules deleted in the terminal end containing the COB gene and the telomeric region; they also possess dimeric molecules resulting from end-to-end junctions of deleted monomers. The two other mitochondrial mutants (Class I) have no detectable gross alteration. Class I and Class II mutants can also be distinguished by the pattern of transmission of the mutation in crosses. An in vivo staining test has been developed to identify rapidly the mutants impaired in cyanide-sensitive respiration. [less ▲]Detailed reference viewed: 17 (1 ULg)
Effect of abscisic and gibberellic acids on malate synthase transcripts in germinating castor bean seeds
; Dommes, Jacques ;
in Plant Molecular Biology (1987), 9Detailed reference viewed: 3 (2 ULg)