Linked Life Data

10076013

Source:http://linkedlifedata.com/resource/pubmed/id/10076013

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1999-3-22
pubmed:abstractText
Numerous sequences of the cytochrome bd quinol oxidase (cytochrome bd) have recently become available for analysis. The analysis has revealed a small number of conserved residues, a new topology for subunit I and a phylogenetic tree involving extensive horizontal gene transfer. There are 20 conserved residues in subunit I and two in subunit II. Algorithms utilizing multiple sequence alignments predicted a revised topology for cytochrome bd, adding two transmembrane helices to subunit I to the seven that were previously indicated by the analysis of the sequence of the oxidase from E. coli. This revised topology has the effect of relocating the N-terminus and C-terminus to the periplasmic and cytoplasmic sides of the membrane, respectively. The new topology repositions I-H19, the putative ligand for heme b595, close to the periplasmic edge of the membrane, which suggests that the heme b595/heme d active site of the oxidase is located near the outer (periplasmic) surface of the membrane. The most highly conserved region of the sequence of subunit I contains the sequence GRQPW and is located in a predicted periplasmic loop connecting the eighth and ninth transmembrane helices. The potential importance of this region of the protein was previously unsuspected, and it may participate in the binding of either quinol or heme d. There are two very highly conserved glutamates in subunit I, E99 and E107, within the third transmembrane helix (E. coli cytochrome bd-I numbering). It is speculated that these glutamates may be part of a proton channel leading from the cytoplasmic side of the membrane to the heme d oxygen-reactive site, now placed near the periplasmic surface. The revised topology and newly revealed conserved residues provide a clear basis for further experimental tests of these hypotheses. Phylogenetic analysis of the new sequences of cytochrome bd reveals considerable deviation from the 16sRNA tree, suggesting that a large amount of horizontal gene transfer has occurred in the evolution of cytochrome bd.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
27
pubmed:volume
1410
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
32-50
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Sequence analysis of cytochrome bd oxidase suggests a revised topology for subunit I.
pubmed:affiliation
School of Chemical Sciences, University of Illinois, Urbana, IL 61801, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.