Molecular design of PhoE porin and its functional consequences
In: Journal of Molecular Biology, Jg. 205 (1989), S. 407-419
Online
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Zugriff:
The three-dimensional structure of PhoE porin from Escherichia coli, negatively stained with uranyl acetate, has been determined by electron crystallographic techniques to a resolution of about 18 A. The structure shows that PhoE porin consists of trimeric stain-filled channels as the basic unit. The trimeric channels converge as they transverse the membrane but they do not merge. Our three-dimensional structure of PhoE porin indicates that there is a short, narrower segment of channel, which extends beyond the visible strain-filled portion of the channel. The map of glucose-embedded PhoE porin in projection normal to the membrane has also been determined to a resolution of 6.5 A. The projected map shows trimeric ring-like structures, which are presumably cylindrical domains of beta-sheet. At the 3-fold symmetry axis of the trimer, there is a low density region, which is suggested to be a site of lipopolysaccharide that is required for channel and bacteriophage receptor activities. The structural model of the PhoE monomer consists of a flattened cylinder with a large water-filled vestibule about 35 A long with an elliptically shaped opening that is 27 A along the major axis and 18 A along the minor axis. The vestibule has a narrower extension about 10 A long with an average diameter of about 10 A. The vestibule wall is formed by beta-sheet, which may have a large fraction of the beta-strands oriented normal to membrane. Our structural model provides a clue as to how the surface charges on the outer membrane may regulate the permeation of ionic solutes through the channel.
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Molecular design of PhoE porin and its functional consequences
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Autor/in / Beteiligte Person: | Jap, Bing K. |
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Zeitschrift: | Journal of Molecular Biology, Jg. 205 (1989), S. 407-419 |
Veröffentlichung: | Elsevier BV, 1989 |
Medientyp: | unknown |
ISSN: | 0022-2836 (print) |
DOI: | 10.1016/0022-2836(89)90351-3 |
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