Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
44
pubmed:dateCreated
1994-12-6
pubmed:abstractText
The heme-copper oxidase superfamily contains all of the mammalian mitochondrial cytochrome c oxidases, as well as most prokaryotic respiratory oxidases. All members of the superfamily have a subunit homologous to subunit I of the mammalian cytochrome c oxidases. This subunit provides the amino acid ligands to a low-spin heme component as well as to a heme-copper binuclear center, which is the site where dioxygen is reduced to water. The amino acid sequence of transmembrane helix VI of subunit I is the most highly conserved within the superfamily. Previous efforts have demonstrated that one of the residues in this region, H284, is critical for oxidase activity and for the assembly of CuB. This paper presents the analysis of additional site-directed mutants in which other highly conserved residues in helix VI (P285, E286, Y288, and P293) have been substituted. Most of the mutants are enzymatically inactive. Structural perturbations reported by Fourier transform infrared absorption difference spectroscopy of CO adducts of the mutant oxidases confirm the previous suggestion that this region is adjactent to CuB. Furthermore, the analysis of five different substitutions for Y288 indicates that all lack CuB. On the basis of these data, it is proposed that Y288 may be a CuB ligand along with H333, H334, and H284, and a plausible molecular model of the CuB site is presented.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
33
pubmed:geneSymbol
cyo, recA
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13013-21
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:7947706-Amino Acid Sequence, pubmed-meshheading:7947706-Animals, pubmed-meshheading:7947706-Computer Simulation, pubmed-meshheading:7947706-Copper, pubmed-meshheading:7947706-Electron Transport Complex IV, pubmed-meshheading:7947706-Escherichia coli, pubmed-meshheading:7947706-Ligands, pubmed-meshheading:7947706-Models, Molecular, pubmed-meshheading:7947706-Molecular Sequence Data, pubmed-meshheading:7947706-Mutagenesis, Site-Directed, pubmed-meshheading:7947706-Oxidation-Reduction, pubmed-meshheading:7947706-Oxygen, pubmed-meshheading:7947706-Protein Conformation, pubmed-meshheading:7947706-Protein Structure, Secondary, pubmed-meshheading:7947706-Proton Pumps, pubmed-meshheading:7947706-Spectrophotometry, Ultraviolet, pubmed-meshheading:7947706-Spectroscopy, Fourier Transform Infrared, pubmed-meshheading:7947706-Tyrosine
pubmed:year
1994
pubmed:articleTitle
Site-directed mutagenesis of residues within helix VI in subunit I of the cytochrome bo3 ubiquinol oxidase from Escherichia coli suggests that tyrosine 288 may be a CuB ligand.
pubmed:affiliation
School of Chemical Sciences, University of Illinois, Urbana 61801.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't