Linked Life Data

10441127

Source:http://linkedlifedata.com/resource/pubmed/id/10441127

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
32
pubmed:dateCreated
1999-9-8
pubmed:abstractText
The isolated T domain of diphtheria toxin was mutated by cysteine-scanning mutagenesis at 28 consecutive sites (residues 328-355) that comprise the TH8 helix and the TL5 interhelical loop in the native toxin. After derivatizing the mutant proteins with a sulfhydryl-selective nitroxide reagent, we examined the mobility of each nitroxide and its accessibility to polar and nonpolar paramagnetic reagents, before and after insertion into phospholipid bilayers. The data obtained with the proteins in solution at pH 8 are generally consistent with predictions from the crystal structure of the toxin. Upon membrane binding at pH 4.6, a major structural reorganization of the domain was seen, which dramatically reduced the accessibility of most residues in this region to the polar reagent nickel(II)-ethylenediaminediacetate complex (NiEDDA). Many of these residues also showed reduced accessibility to the nonpolar reagent O(2). Periodic accessibility of the nitroxide side chains along the sequence to these reagents shows that TH8 remains largely helical in the membrane-bound state, with one surface associated with protein and the other facing the hydrophobic interior of the bilayer. In addition, the TL5 loop also appears to become alpha-helical in the membrane, with one surface in contact with protein and the other in contact with the bilayer interior. These findings provide a structural framework for understanding how the T domain forms a transmembrane channel and mediates translocation of diphtheria toxin's enzymic moiety across a membrane.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10336-43
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Conformation of the diphtheria toxin T domain in membranes: a site-directed spin-labeling study of the TH8 helix and TL5 loop.
pubmed:affiliation
Jules Stein Eye Institute, Department of Chemistry and Biochemistry, University of California Los Angeles 90095-7008, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't