Linked Life Data

9772185

Source:http://linkedlifedata.com/resource/pubmed/id/9772185

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
41
pubmed:dateCreated
1998-11-3
pubmed:abstractText
Clostridium perfringens perfringolysin O (PFO or theta-toxin) is a cytolytic toxin that binds to cholesterol-containing membranes and then self-associates to spontaneously form aqueous pores of varying size in the bilayer. In this study, a membrane-spanning domain has been identified in PFO by a combination of fluorescence spectroscopic methods using the fluorescent dye N, N'-dimethyl-N-(iodoacetyl)-N'-(7-nitrobenz-2-oxa-1, 3-diazolyl)ethylenediamine (NBD) whose emission properties are sensitive to water. PFO was substituted with a single cysteine at most of the residues between amino acids K189 and N218, and then each cysteine was modified with NBD. Each purified NBD-labeled PFO was then bound to membranes, and the probe's environment was ascertained by measuring its fluorescence lifetime, emission intensity, and collisional quenching with either aqueous (iodide ions) or nonaqueous (nitroxide-labeled phospholipids) quenchers. Lifetime and intensity measurements revealed that the amino acid side chains in this region of the membrane-bound PFO polypeptide alternated between being in an aqueous or a nonaqueous environment. This pattern indicates that this portion of the membrane-bound PFO spans the membrane in an antiparallel beta-sheet conformation. The alternating exposure of these residues to the hydrophobic interior of the bilayer was demonstrated by their susceptibility to quenching by nitroxide moieties attached to phospholipid acyl chains. Residues K189-N218 therefore form a two-stranded, amphipathic beta-sheet in the membrane-bound PFO that creates a stable interface between the pore and the membrane. This same region packs as three short alpha-helices in the soluble, monomeric form of PFO, and therefore, the cholesterol-dependent conversion of PFO to a membrane-bound oligomer involves a major structural transition in which three alpha-helices unfold to form a membrane-spanning amphipathic beta-sheet.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
13
pubmed:volume
37
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14563-74
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:9772185-Amino Acid Sequence, pubmed-meshheading:9772185-Bacterial Toxins, pubmed-meshheading:9772185-Clostridium perfringens, pubmed-meshheading:9772185-Fluorescence Polarization, pubmed-meshheading:9772185-Fluorescent Dyes, pubmed-meshheading:9772185-Hemolysin Proteins, pubmed-meshheading:9772185-Humans, pubmed-meshheading:9772185-Light, pubmed-meshheading:9772185-Membrane Proteins, pubmed-meshheading:9772185-Molecular Sequence Data, pubmed-meshheading:9772185-Mutagenesis, Site-Directed, pubmed-meshheading:9772185-Oxadiazoles, pubmed-meshheading:9772185-Peptide Fragments, pubmed-meshheading:9772185-Phospholipids, pubmed-meshheading:9772185-Protein Structure, Secondary, pubmed-meshheading:9772185-Scattering, Radiation, pubmed-meshheading:9772185-Spectrometry, Fluorescence, pubmed-meshheading:9772185-Spin Labels, pubmed-meshheading:9772185-Sulfhydryl Compounds
pubmed:year
1998
pubmed:articleTitle
Identification of a membrane-spanning domain of the thiol-activated pore-forming toxin Clostridium perfringens perfringolysin O: an alpha-helical to beta-sheet transition identified by fluorescence spectroscopy.
pubmed:affiliation
Department of Microbiology and Immunology, The University of Oklahoma Health Sciences Center, Oklahoma City 53190, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't