학술논문
The NuoI subunit of the Rhodobacter capsulatus respiratory Complex I (equivalent to the bovine TYKY subunit) is required for proper assembly of the membraneous and peripheral domains of the enzyme.
Document Type
Article
Author
Source
Subject
*MUTAGENESIS
*COMPLEX ions
*GENES
*IMMUNOCHEMISTRY
*ELECTRON paramagnetic resonance
*BIOCHEMISTRY
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Language
ISSN
0014-2956
Abstract
The nuol gene that encodes a ferredoxin-like subunit of the Rhodobacter capsulatus Complex I (a subunit equivalent to the bovine TYKY subunit) was mutated by homologous recombination. Both a nuol-deleted mutant (Δnuol mutant) and a point mutant in which Cys74 was replaced by a serine (C74S mutant) proved to be completely deficient in Complex I activity. These strains were unable to grow under anaerobic photosynthetic conditions. Their cytoplasmic membranes were also characterized by the absence of specific EPR signals assigned to FeS clusters N1 and N2. lmmunochemical analysis of the mutant membranes with subunit-specific antibodies showed that the peripheral subunits were not assembled. Trans-complementation of the mutant strains by a native nuol gene restored the wild-type phenotypes. In the C74S mutant, a limited amount of Nuol subunit still bound to the membraneous domain of Complex I, which is an indication that Nuol directly interacts with this domain. All these results clearly show that Nuol plays a critical role in the connection between the membraneous domain and the peripheral domain of Complex I. [ABSTRACT FROM AUTHOR]