Mitochondrial genetics of Chlamydomonas reinhardtii: resistance mutations marking the cytochrome b gene.
We describe the genetic and molecular analysis of the first non-Mendelian mutants of Chlamydomonas reinhardtii resistant to myxothiazol, an inhibitor of the respiratory cytochrome bc1 complex. Using a set of seven oligonucleotide probes, restriction fragments containing the mitochondrial cytochrome b (cyt b) gene from C. reinhardtii were isolated from a mitochondrial DNA library. This gene is located adjacent to the gene for subunit 4 of the mitochondrial NADH-dehydrogenase (ND4), near one end of the 15.8-kb linear mitochondrial genome of C. reinhardtii. The algal cytochrome b apoprotein contains 381 amino-acid residues and exhibits a sequence similarity of about 59% with other plant cytochrome b proteins. The cyt b gene from four myxothiazol resistant mutants of C. reinhardtii was amplified for DNA sequence analysis. In comparison to the wild-type strain, all mutants contain an identical point mutation in the cyt b gene, leading to a change of a phenylalanine codon to a leucine codon at amino acid position 129 of the cytochrome b protein. Segregation analysis in tetrads from reciprocal crosses of mutants with wild type shows a strict uniparental inheritance of this mutation from the mating type minus parent (UP-). However, mitochondrial markers from both parents are recovered in vegetative diploids in variable proportions from one experiment to the next for a given cross. On the average, a strong bias is seen for markers inherited from the mating type minus parent.
Bennoun
P
P
Institut de Biologie Physico-Chimique, Paris, France.
Delosme
M
M
Kück
U
U
D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000494:pharmacology; D001483:Base Sequence; D002696:Chlamydomonas / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D003433:Crosses, Genetic; D003573:Cytochrome b Group / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics* / Q000302:isolation & purification; D004171:Diploidy; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006238:Haploidy; D008689:Methacrylates; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D009154:Mutation; D009245:NADH Dehydrogenase / Q000235:genetics; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D000073739:Strobilurins; D013844:Thiazoles / Q000494:pharmacology
D000935:Antifungal Agents; D003573:Cytochrome b Group; D004272:DNA, Mitochondrial; D005231:Fatty Acids, Unsaturated; D008689:Methacrylates; D015345:Oligonucleotide Probes; D000073739:Strobilurins; D013844:Thiazoles; C008556:mucidin; C030517:myxothiazol; D009245:NADH Dehydrogenase