tailieunhanh - Báo cáo khóa học: Disruption of the interaction between the Rieske iron–sulfur protein and cytochrome b in the yeast bc1 complex owing to a human disease-associated mutation within cytochrome b

The mitochondrial cytochromeb missense mutation, G167E, has been reported inapatientwithcardiomyopathy. The residue G167 is located in an extramembranous helix close to the hinge region of the iron–sulfur protein. In order to characterize the effects of the mutation on the structure and function of thebc1complex, we introducedG167E into the highly similar yeast cytochromeb. The mutation had a severe effect on the respiratory function, with the activity of thebc1complex decreased to a fewper cent of the wild type | Eur. J. Biochem. 271 1292-1298 2004 FEBS 2004 doi Disruption of the interaction between the Rieske iron-sulfur protein and cytochrome b in the yeast bc1 complex owing to a human disease-associated mutation within cytochrome b Nicholas Fisher1 Inarid Bouraes1. Philip Hill1 Gael Brasseur2 and Briaitte Meunier1 1 Wolfson Institute for Biomedical Research University College London UK 2Laboratoire de Bioénergétique et Ingenierie des Proteines CNRS Marseille France The mitochondrial cytochrome b missense mutation G167E has been reported in a patient with cardiomyopathy. The residue G167 is located in an extramembranous helix close to the hinge region of the iron-sulfur protein. In order to characterize the effects of the mutation on the structure and function of the bc1 complex we introduced G167E into the highly similar yeast cytochrome b. The mutation had a severe effect on the respiratory function with the activity of the bc1 complex decreased to a few per cent of the wild type. Analysis of the enzyme activity indicated that the mutation affected its stability which could be the result of an altered binding of the iron-sulfur protein on the complex. G167E had no major effect on the interaction between the ironsulfur protein headgroup and the quinol oxidation site as judged by the electron paramagnetic resonance signal and only a minor effect on the rate of cytochrome b reduction but it severely reduced the rate of cytochrome c1 reduction. This suggested that the mutation G167E could hinder the movement of the iron-sulfur protein probably by distorting the structure of the hinge region. The function of bc1 was partially restored by mutations W164L and W166L located close to the primary change which reduced the steric hindrance caused by G167E. Taken together these observations suggest that the protein-protein interaction between the n-sulfur protein hinge region and the cytochrome b extramembranous cd2 helix is important for maintaining