Functional mapping reveals the importance of yeast cytochrome b C-terminal region in assembly and function of the bc1 complex.
Genetic and molecular analyses have been undertaken for four respiratory deficient mutants (mit-). The four mutations affect the C-terminal region of apocytochrome b. The frameshift (L263STOP) and non-sense (Q338STOP) mutations give rise to a truncated apocytochrome b. The mutant G337R conserves only 32% of its NADH oxidase activity which suggests that the presence of a positively charged amino acid in the transmembranous helix 7 of cytochrome b alters, either directly or indirectly, the bc1 function, without affecting its assembly. The mutation G352V has a 65% loss of cytochrome b spectral content and prevents all of the mitochondrial respiratory activity. This leads us to believe that the glycine, conserved in position 352, may play a crucial role in bc1 complex function.
Edderkaoui
B
B
Laboratoire de Génétique Microbienne, Louvain-La-Neuve, Belgium.
Meunier
B
B
Colson-Corbisier
A M
AM
D000595:Amino Acid Sequence; D003573:Cytochrome b Group / Q000737:chemistry* / Q000235:genetics*; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000302:isolation & purification; D014450:Electron Transport Complex III / Q000378:metabolism* / Q000502:physiology*; D016368:Frameshift Mutation; D008969:Molecular Sequence Data; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D013329:Structure-Activity Relationship
D003573:Cytochrome b Group; D004272:DNA, Mitochondrial; D014450:Electron Transport Complex III