Document Detail


Heme ligand identification and redox properties of the cytochrome c synthetase, CcmF.
MedLine Citation:
PMID:  22066495     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Cytochrome c maturation in many bacteria, archaea, and plant mitochondria involves the integral membrane protein CcmF, which is thought to function as a cytochrome c synthetase by facilitating the final covalent attachment of heme to the apocytochrome c. We previously reported that the E. coli CcmF protein contains a b-type heme that is stably and stoichiometrically associated with the protein and is not the heme attached to apocytochrome c. Here, we show that mutation of either of two conserved transmembrane histidines (His261 or His491) impairs stoichiometric b-heme binding in CcmF and results in spectral perturbations in the remaining heme. Exogeneous imidazole is able to correct cytochrome c maturation for His261 and His491 substitutions with small side chains (Ala or Gly), suggesting that a "cavity" is formed in these CcmF mutants in which imidazole binds and acts as a functional ligand to the b-heme. The results of resonance Raman spectroscopy on wild-type CcmF are consistent with a hexacoordinate low-spin b-heme with at least one endogeneous axial His ligand. Analysis of purified recombinant CcmF proteins from diverse prokaryotes reveals that the b-heme in CcmF is widely conserved. We have also determined the reduction potential of the CcmF b-heme (E(m,7) = -147 mV). We discuss these results in the context of CcmF structure and functions as a heme reductase and cytochrome c synthetase.
Authors:
Brian San Francisco; Eric C Bretsnyder; Kenton R Rodgers; Robert G Kranz
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2011-11-21
Journal Detail:
Title:  Biochemistry     Volume:  50     ISSN:  1520-4995     ISO Abbreviation:  Biochemistry     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2011-12-13     Completed Date:  2012-02-13     Revised Date:  2014-09-16    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  10974-85     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Substitution
Binding Sites
Biocatalysis
Enzyme Activation / drug effects
Escherichia coli Proteins / chemistry,  genetics,  isolation & purification,  metabolism*
Heme / chemistry,  metabolism*
Histidine / chemistry
Holoenzymes / chemistry,  genetics,  isolation & purification,  metabolism
Imidazoles / pharmacology
Indicators and Reagents / pharmacology
Ligands
Lyases / chemistry,  genetics,  isolation & purification,  metabolism*
Models, Molecular
Mutant Proteins / chemistry,  isolation & purification,  metabolism
Oxidation-Reduction
Phylogeny
Protein Conformation
Protein Subunits / chemistry,  genetics,  isolation & purification,  metabolism
Recombinant Proteins / chemistry,  isolation & purification,  metabolism
Spectrum Analysis, Raman
Grant Support
ID/Acronym/Agency:
AI072719/AI/NIAID NIH HHS; GM47909/GM/NIGMS NIH HHS; R01 GM047909/GM/NIGMS NIH HHS; R01 GM047909-17/GM/NIGMS NIH HHS; R15 AI072719/AI/NIAID NIH HHS
Chemical
Reg. No./Substance:
0/Escherichia coli Proteins; 0/Holoenzymes; 0/Imidazoles; 0/Indicators and Reagents; 0/Ligands; 0/Mutant Proteins; 0/Protein Subunits; 0/Recombinant Proteins; 42VZT0U6YR/Heme; 4QD397987E/Histidine; 7GBN705NH1/imidazole; EC 4.-/Lyases; EC 4.4.1.17/cytochrome C synthetase
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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