Linked Life Data

20941706

Source:http://linkedlifedata.com/resource/pubmed/id/20941706

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2010-12-1
pubmed:abstractText
Colicins are water-soluble toxins that, upon interaction with membranes, undergo a conformational change, insert, and form pores in them. Pore formation activity is localized in a bundle of 10 ?-helices named the pore-forming domain (PFD). There is evidence that colicins attach to the membrane via a hydrophobic hairpin embedded in the core of the PFD. Two main models have been suggested for the membrane-bound state: penknife and umbrella, differing in regard to the orientation of the hydrophobic hairpin with respect to the membrane. The arrangement of the amphipathic helices has been described as either a compact three-dimensional structure or a two-dimensional array of loosely interacting helices on the membrane surface. Using molecular dynamics simulations with an implicit membrane model, we studied the structure and stability of the conformations proposed earlier for four colicins. We find that colicins are initially driven towards the membrane by electrostatic interactions between basic residues and the negatively charged membrane surface. They do not have a unique binding orientation, but in the predominant orientations the central hydrophobic hairpin is parallel to the membrane. In the inserted state, the estimated free energy tends to be lower for the compact arrangements of the amphipathic helix, but the more expanded ones are in better agreement with experimental distance distributions. The difference in energy between penknife and umbrella conformations is small enough for equilibrium to exist between them. Elongation of the hydrophobic hairpin helices and membrane thinning were found unable to produce stabilization of the transmembrane configuration of the hydrophobic hairpin.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
1097-0134
pubmed:author
pubmed:copyrightInfo
Copyright © 2010 Wiley-Liss, Inc.
pubmed:issnType
Electronic
pubmed:volume
79
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
126-41
pubmed:dateRevised
2011-9-26
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
Computational studies of colicin insertion into membranes: the closed state.
pubmed:affiliation
Department of Chemistry, The City College of CUNY, New York, New York 10031, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, N.I.H., Extramural