Linked Life Data

9378723

Source:http://linkedlifedata.com/resource/pubmed/id/9378723

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1997-11-10
pubmed:abstractText
Cytochrome bo is a four-subunit quinol oxidase in the aerobic respiratory chain of Escherichia coli and functions as a redox-coupled proton pump. Subunit I binds all the redox metal centers, low-spin heme b, high-spin heme o, and Cu(B), and serves as a reaction center of the oxidase complex. This work focuses on the functional and structural roles of 14 charged amino acid residues that are conserved in subunit I of the heme-copper terminal oxidases. Substitutions of Lys55, Tyr173, Asp188, Asp256, Arg481, and Arg482 by neutral amino acid residues did not affect the catalytic activity and spectroscopic properties of the cytoplasmic membranes. In contrast, genetic complementation tests indicated that replacements of Arg80, Asp135, Arg257, Glu286, Tyr288, Lys362, Asp407, and Glu540 resulted in nonfunctional enzymes. The R80Q mutation caused loss of a diagnostic peak for low-spin heme b in the 77 K redox difference spectrum. The K362Q, D407N, and E540Q mutations affected the CO-binding by the heme-copper binuclear center. The D135N, R257Q, E286Q, and Y288F mutations specifically eliminated the Cu(B) center from the oxidase complex, whereas the E286D mutant did not show significant perturbations on the redox metal centers even though it was still inactive. Based on these findings and recent crystallographic studies on cytochrome c oxidases, we discuss the possible roles of the conserved charged amino acid residues in subunit I of the heme-copper terminal oxidases.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-924X
pubmed:author
pubmed:issnType
Print
pubmed:volume
122
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
422-9
pubmed:dateRevised
2007-12-19
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Substitutions of charged amino acid residues conserved in subunit I perturb the redox metal centers of the Escherichia coli bo-type ubiquinol oxidase.
pubmed:affiliation
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't