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Another look at the interaction between mitochondrial cytochrome c and flavocytochrome b (2).
MedLine Citation:
PMID:  21503671     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Yeast flavocytochrome b (2) tranfers reducing equivalents from lactate to oxygen via cytochrome c and cytochrome c oxidase. The enzyme catalytic cycle includes FMN reduction by lactate and reoxidation by intramolecular electron transfer to heme b (2). Each subunit of the soluble tetrameric enzyme consists of an N terminal b (5)-like heme-binding domain and a C terminal flavodehydrogenase. In the crystal structure, FMN and heme are face to face, and appear to be in a suitable orientation and at a suitable distance for exchanging electrons. But in one subunit out of two, the heme domain is disordered and invisible. This raises a central question: is this mobility required for interaction with the physiological acceptor cytochrome c, which only receives electrons from the heme and not from the FMN? The present review summarizes the results of the variety of methods used over the years that shed light on the interactions between the flavin and heme domains and between the enzyme and cytochrome c. The conclusion is that one should consider the interaction between the flavin and heme domains as a transient one, and that the cytochrome c and the flavin domain docking areas on the heme b (2) domain must overlap at least in part. The heme domain mobility is an essential component of the flavocytochrome b (2) functioning. In this respect, the enzyme bears similarity to a variety of redox enzyme systems, in particular those in which a cytochrome b (5)-like domain is fused to proteins carrying other redox functions.
Authors:
Florence Lederer
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-4-19
Journal Detail:
Title:  European biophysics journal : EBJ     Volume:  -     ISSN:  1432-1017     ISO Abbreviation:  -     Publication Date:  2011 Apr 
Date Detail:
Created Date:  2011-4-19     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8409413     Medline TA:  Eur Biophys J     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Laboratoire de Chimie Physique, Faculté des Sciences, Université Paris-Sud, 91405, Orsay Cedex, France, florence.lederer@u-psud.fr.
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