1kyo
YEAST CYTOCHROME BC1 COMPLEX WITH BOUND SUBSTRATE CYTOCHROME C
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OverviewOverview
Small diffusible redox proteins facilitate electron transfer in, respiration and photosynthesis by alternately binding to integral membrane, proteins. Specific and transient complexes need to be formed between the, redox partners to ensure fast turnover. In respiration, the mobile, electron carrier cytochrome c shuttles electrons from the cytochrome bc1, complex to cytochrome c oxidase. Despite extensive studies of this, fundamental step of energy metabolism, the structures of the respective, electron transfer complexes were not known. Here we present the crystal, structure of the complex between cytochrome c and the cytochrome bc1, complex from Saccharomyces cerevisiae. The complex was crystallized with, the help of an antibody fragment, and its structure was determined at, 2.97-A resolution. Cytochrome c is bound to subunit cytochrome c1 of the, enzyme. The tight and specific interactions critical for electron transfer, are mediated mainly by nonpolar forces. The close spatial arrangement of, the c-type hemes unexpectedly suggests a direct and rapid heme-to-heme, electron transfer at a calculated rate of up to 8.3 x 10(6) s(-1)., Remarkably, cytochrome c binds to only one recognition site of the, homodimeric multisubunit complex. Interestingly, the occupancy of quinone, in the Qi site is higher in the monomer with bound cytochrome c, suggesting a coordinated binding and reduction of both electron-accepting, substrates. Obviously, cytochrome c reduction by the cytochrome bc1, complex can be regulated in response to respiratory conditions.
About this StructureAbout this Structure
1KYO is a Protein complex structure of sequences from Mus musculus and Saccharomyces cerevisiae with HEM, FES and SMA as ligands. The following page contains interesting information on the relation of 1KYO with [Cytochrome c]. Active as Ubiquinol--cytochrome-c reductase, with EC number 1.10.2.2 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of the yeast cytochrome bc1 complex with its bound substrate cytochrome c., Lange C, Hunte C, Proc Natl Acad Sci U S A. 2002 Mar 5;99(5):2800-5. PMID:11880631
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