Linked Life Data

19928831

Source:http://linkedlifedata.com/resource/pubmed/id/19928831

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
51
pubmed:dateCreated
2009-12-22
pubmed:abstractText
The R481 residue of cytochrome bo(3) ubiquinol oxidase from E. coli is highly conserved in the heme-copper oxidase superfamily. It has been postulated to serve as part of a proton loading site that regulates proton translocation across the protein matrix of the enzyme. Along these lines, proton pumping efficiency has been demonstrated to be abolished in many R481 mutants. However, R481Q in bo(3) from E. coli has been shown to be fully functional, implying that the positive charge of the arginine is not required for proton translocation [ Puustinen , A. and Wikstrom , M. ( 1999 ) Proc. Natl. Acad. Sci. U.S.A. 96 , 35 - 37 ]. In an effort to delineate the structural role of R481 in the bo(3) oxidase, we used resonance Raman spectroscopy to compare the nonfunctional R481L mutant and the functional R481Q mutant, to the wild type protein. Resonance Raman data of the oxidized and reduced forms of the R481L mutant indicate that the mutation introduces changes to the heme o(3) coordination state, reflecting a change in position and/or coordination of the Cu(B) located on the distal side of heme o(3), although it is approximately 10 A away from R481. In the reduced-CO adduct of R481L, the frequencies of the Fe-CO and C-O stretching modes indicate that, unlike the wild type protein, the Cu(B) is no longer close to the heme-bound CO. In contrast, resonance Raman data obtained from the various oxidation and ligation states of the R481Q mutant are similar to those of the wild type protein, except that the mutation causes an enhancement of the relative intensity of the beta conformer of the CO-adduct, indicating a shift in the equilibrium between the alpha and beta conformers. The current findings, together with crystallographic structural data of heme-copper oxidases, indicate that R481 plays a keystone role in stabilizing the functional structure of the Cu(B) site through a hydrogen bonding network involving ordered water molecules. The implications of these data on the proton translocation mechanism are considered.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
1520-4995
pubmed:author
pubmed:issnType
Electronic
pubmed:day
29
pubmed:volume
48
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12113-24
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Communication between R481 and Cu(B) in cytochrome bo(3) ubiquinol oxidase from Escherichia coli.
pubmed:affiliation
Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, N.I.H., Extramural