FEBS Letters | |
The C‐terminal domain of yeast cytochrome b is essential for a correct assembly of the mitochondrial cytochrome bc 1 complex | |
di Rago, Jean-Paul1  Lazowska, Jaga1  Macadre, Catherine1  Slonimski, Piotr P.1  | |
[1] Centre de Génétique Moléculaire du Centre National de la Recherche Scientifique, Laboratoire propre associé á l'Université Pierre et Marie Curie, Gif-sur-Yvette F-91198, France | |
关键词: Cytochrome bc 1 complex assembly; Yeast; Mutation; Mitochondrion; Genetics; | |
DOI : 10.1016/0014-5793(93)80984-3 | |
学科分类:生物化学/生物物理 | |
来源: John Wiley & Sons Ltd. | |
【 摘 要 】
Yeast mutants modifying the C-terminal region of mitochondrial cytochrome b were isolated and characterized. A nonsense mutation of the leucine codon 335 (TTA → TAA), 50 residues before the normal C-terminus, blocks incorporation of heme into the apocytochrome b and prevents growth on non-fermentable substrates. The same defects were observed in a frameshift mutant (after codon 348, TAT → TATT) in which the last 37 C-terminal residues are predicted to be replaced by a novel sequence of 33 amino acids. Function was regained in the nonsense mutant only by true back mutations restoring a protein of the wild-type sequence. The respiratory capacity was restored to wild-type levels in the frameshift mutant by a variety of single base subtractions located within a window of 24 bases before or after the original +T addition, these pseudo-reversions resulted in single or multiple (up to five) consecutive amino acid replacements between positions 346 and 354 and restored the wild-type sequence from position 355 to 385. These data, combined with hydropathy calculations and sequence comparisons, suggest that the C-terminal domain of cytochrome b forms a transmembrane segment essential for the correct assembly of the cytochrome bc 1 complex.
【 授权许可】
Unknown
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