1mpf: Difference between revisions

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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. 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 Sat May 3 01:33:33 2008

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OCA

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 [[Image:1mpf.gif|left|200px]]
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 '''STRUCTURAL AND FUNCTIONAL ALTERATIONS OF A COLICIN RESISTANT MUTANT OF OMPF-PORIN FROM ESCHERICHIA COLI'''
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 [[Category: Single protein]]
 [[Category: Schirmer, T.]]
-[[Category: membrane protein]]
+[[Category: Membrane protein]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 01:33:33 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 22:19:17 2008''