Document Detail

Conserved glycine 232 in the ligand channel of ba3 cytochrome oxidase from Thermus thermophilus.
MedLine Citation:
PMID:  24937405     Owner:  NLM     Status:  MEDLINE    
Knowing how the protein environment modulates ligand pathways and redox centers in the respiratory heme-copper oxidases is fundamental for understanding the relationship between the structure and function of these enzymes. In this study, we investigated the reactions of O2 and NO with the fully reduced G232V mutant of ba3 cytochrome c oxidase from Thermus thermophilus (Tt ba3) in which a conserved glycine residue in the O2 channel of the enzyme was replaced with a bulkier valine residue. Previous studies of the homologous mutant of Rhodobacter sphaeroides aa3 cytochrome c oxidase suggested that the valine completely blocked the access of O2 to the active site [Salomonsson, L., et al. (2004) Proc. Natl. Acad. Sci. U.S.A. 101, 11617-11621]. Using photolabile O2 and NO carriers, we find by using time-resolved optical absorption spectroscopy that the rates of O2 and NO binding are not significantly affected in the Tt ba3 G232V mutant. Classical molecular dynamics simulations of diffusion of O2 to the active site in the wild-type enzyme and G232V mutant show that the insertion of the larger valine residue in place of the glycine appears to open up other O2 and NO exit/entrance pathways that allow these ligands unhindered access to the active site, thus compensating for the larger valine residue.
William McDonald; Chie Funatogawa; Yang Li; Ying Chen; Istvan Szundi; James A Fee; C David Stout; Olöf Einarsdóttir
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2014-07-07
Journal Detail:
Title:  Biochemistry     Volume:  53     ISSN:  1520-4995     ISO Abbreviation:  Biochemistry     Publication Date:  2014 Jul 
Date Detail:
Created Date:  2014-07-15     Completed Date:  2014-09-09     Revised Date:  2014-11-07    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4467-75     Citation Subset:  IM    
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MeSH Terms
Amino Acid Sequence
Amino Acid Substitution
Bacterial Proteins / chemistry*
Catalytic Domain
Conserved Sequence
Crystallography, X-Ray
Cytochrome b Group / chemistry*,  genetics
Electron Transport Complex IV / chemistry*,  genetics
Glycine / chemistry*
Molecular Dynamics Simulation
Nitric Oxide / chemistry
Oxygen / chemistry
Protein Conformation
Recombinant Proteins / chemistry,  genetics
Thermus thermophilus / chemistry*
Valine / chemistry
Grant Support
Reg. No./Substance:
0/Bacterial Proteins; 0/Cytochrome b Group; 0/Ligands; 0/Recombinant Proteins; 31C4KY9ESH/Nitric Oxide; EC 1.-/cytochrome ba3; EC Transport Complex IV; HG18B9YRS7/Valine; S88TT14065/Oxygen; TE7660XO1C/Glycine

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

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