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Subunit organisation and symmetry of pore‐forming, oligomeric pneumolysin
Author(s) -
Morgan Peter J.,
Hyman Stefan C.,
Rowe Arthur J.,
Mitchell Timothy J.,
Andrew Peter W.,
Saibil Helen R.
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00887-f
Subject(s) - pneumolysin , protein subunit , oligomer , monomer , negative stain , rotational symmetry , domain (mathematical analysis) , asymmetry , cryo electron microscopy , tetramer , chemistry , projection (relational algebra) , crystallography , molecular physics , electron microscope , biophysics , materials science , physics , biology , polymer chemistry , optics , biochemistry , mathematics , bacterial protein , gene , organic chemistry , polymer , mathematical analysis , algorithm , enzyme , quantum mechanics , mechanics
We present a detailed analysis of the oligomeric subunit organisation of pneumolysin by the use of negative stain electron microscopy and image processing to produce a projection density map. Analysis of the rotational symmetry has revealed a large and variable subunit number, between 40–50. The projected subunit density by rotational averaging shows at least two distinct subunit domains at different radial positions. Side views of the rings reveal further details concerning the dimensions of the oligomer in the membrane. On the basis of these observations and our previous knowledge of the monomer domain structure we propose that the 4‐domain subunits are packed in a square planar arrangement to form the pneumolysin oligomer.