The aromatic domain 66YWYWW70 of subunit VIII of the yeast ubiquinol‐cytochrome c oxidoreductase is important for both assembly and activity of the enzyme

FEBS Letters

Berden, Jan A²  Grivell, Leslie A¹  Lobo-Hajdu, Gisele²  van Gaalen, Monique² 

[1] Section for Molecular Biology, Department of Molecular Cell Biology, BioCentrum, University of Amsterdam, The Netherlands;E.C. Slater Institute, BioCentrum, University of Amsterdam, The Netherlands

关键词: Ubiquinol-cytochrome c oxidoreductase;    11-kDa subunit;    Mutagenesis;    Aromatic domain;    Assembly;    Turnover number;    Saccharomyces cerevisiae;   

DOI  :  10.1016/0014-5793(96)01040-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The aromatic character of the region ⁶⁶YWYWW⁷⁰ of the 11-kDa subunit VIII of ubiquinol-cytochrome c oxidoreductase (bc ₁ complex) of the yeast Saccharomyces cerevisiae has previously been demonstrated to be important for assembly of a functional complex [Hemrika et al. (1994) FEBS Lett. 344, 15–19]. Especially the aromatic nature of residue 66 appeared to be relevant, as the very low level (5%) of bc ₁ complex in the mutant ⁶⁶SASAA⁷⁰ was restored to nearly 70% of the wild-type level in a phenotypic revertant with the sequence ⁶⁶FASAA⁷⁰. In the present study, three other site-directed mutants (⁶⁶SAYAA⁷⁰, ⁶⁶SASAW⁷⁰ and ⁶⁶SWYWW⁷⁰) were constructed and analysed. The data indicate that the presence of one aromatic residue is enough for a substantial level of assembly and that its position modulates the level of both assembly and electron transfer activity. The results also confirm the relevance of this region of subunit VIII for the formation of the Q _out reaction domain, as reported by Hemrika et al. [(1993) Eur. J. Biochem. 215, 601–609]. It is further shown that the lowered specific activity of the mutant described by these authors is not due to the introduction of a cysteine in the sequence of subunit VIII.

【 授权许可】

Unknown