Premium
Negative staining of freeze‐fractured envelopes of Escherichia coli K 12
Author(s) -
Nermut M. V.,
Burdett I. D. J.,
Williams L. D.
Publication year - 1978
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1978.tb00133.x
Subject(s) - bacterial outer membrane , membrane , negative stain , staining , biophysics , strain (injury) , chemistry , fragmentation (computing) , inner membrane , escherichia coli , biology , anatomy , electron microscope , biochemistry , optics , physics , ecology , genetics , gene
SUMMARY Envelope fragments of E. coli K 12 have been produced by freeze‐fracturing ‘by hand’ and negatively stained after thawing. The outer leaflet of the plasma membrane disintegrated upon thawing whereas the outer leaflet of the outer membrane did not. Negative staining revealed the following structural features on the outer membrane fragments: (i) ‘grooves’ 4–6 nm wide, (ii) spherical particles 6–8 nm in diameter, (iii) ‘black dots’ 3–8 nm in diameter. Treatment of cells with EDTA before freeze‐fracturing caused dilatation of grooves into holes eventually leading to fragmentation of the outer membrane. A mutant strain deficient in two outer membrane proteins fractured exclusively through the outer membrane. The outer leaflets so obtained disintegrated upon thawing similarly as observed for the outer leaflet of the plasma membrane.