1mpf
|
STRUCTURAL AND FUNCTIONAL ALTERATIONS OF A COLICIN RESISTANT MUTANT OF OMPF-PORIN FROM ESCHERICHIA COLI
OverviewOverview
A strain of Escherichia coli, selected on the basis of its resistance to, colicin N, reveals distinct structural and functional alterations in, unspecific OmpF porin. A single mutation [Gly-119-->Asp (G119D)] was, identified in the internal loop L3 that contributes critically to the, formation of the construction inside the lumen of the pore. X-ray, structure analysis to a resolution of 3.0 A reveals a locally altered, peptide backbone, with the side chain of residue Asp-119 protruding into, the channel, causing the area of the constriction (7 x 11 A in the wild, type) to be subdivided into two intercommunicating subcompartments of 3-4, A in diameter. The functional consequences of this structural modification, consist of a reduction of the channel conductance by about one-third, of, altered ion selectivity and voltage gating, and of a decrease of, permeation rates of various sugars by factors of 2-12. The structural, modification of the mutant protein affects neither the beta-barrel, structure nor those regions of the molecule that are exposed at the cell, surface. Considering the colicin resistance of the mutant, it is inferred, that in vivo, colicin N traverses the outer membrane through the porin, channel or that the dynamics of the exposed loops are affected in the, mutant such that these may impede the binding of the toxin.
About this StructureAbout this Structure
1MPF is a Single protein structure of sequence from Escherichia coli with C8E as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Structural and functional alterations of a colicin-resistant mutant of OmpF porin from Escherichia coli., Jeanteur D, Schirmer T, Fourel D, Simonet V, Rummel G, Widmer C, Rosenbusch JP, Pattus F, Pages JM, Proc Natl Acad Sci U S A. 1994 Oct 25;91(22):10675-9. PMID:7524100
Page seeded by OCA on Tue Nov 20 21:36:29 2007