Article ID Journal Published Year Pages File Type
1942606 Biochimica et Biophysica Acta (BBA) - Bioenergetics 2011 7 Pages PDF
Abstract

The cytochrome bc1 complex is a key component in several respiratory pathways. One of the characteristics of the eukaryotic complex is the presence of a small acidic subunit, which is thought to guide the interaction of the complex with its electron acceptor and facilitate electron transfer. Paracoccus denitrificans represents the only example of a prokaryotic organism in which a highly acidic domain is covalently fused to the cytochrome c1 subunit. In this work, a deletion variant lacking this acidic domain has been produced and purified by affinity chromatography. The complex is fully intact as shown by its X-ray structure, and is a dimer (Kleinschroth et al., subm.) compared to the tetrameric (dimer-of-dimer) state of the wild-type. The variant complex is studied by steady-state kinetics and flash photolysis, showing wild type turnover and a virtually identical interaction with its substrate cytochrome c552.

► The role of a unique acidic domain in the c1 subunit of complex III is addressed. ► In a deletion variant, neither kCAT nor KM are changed. ► Laser flash photolysis indicates same substrate interaction in the variant complex.

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