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Structure of the porin from a bacterial stalk
Author(s) -
Chalcroft J.P.,
Engelhardt H.,
Baumeister W.
Publication year - 1987
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(87)81273-5
Subject(s) - porin , bacterial outer membrane , membrane , crystallography , stalk , isotropy , electron microscope , crystal structure , biophysics , escherichia coli , chemistry , biology , materials science , physics , optics , biochemistry , horticulture , gene
The stalks (hyphae) of a prosthecate bacterium, directly sampled from the water surface of a hot pond, show extended regular patterns on their envelope in the electron microscope. Image processing revealed a structure of the crystalline complexes which is very similar to the gross morphology of the Escherichia coli porins OmpC and OmpF. The natural two‐dimensional crystal of the outer membrane protein has p3 symmetry and a lattice constant of 7.95 nm. The three‐dimensional structure of the stalk porin has been determined to an almost isotropic resolution of 1.7 nm. The reconstruction revealed a complex network of channels within the membrane matrix with a triplet of pores merging into a common outlet, similar to the structure of the E. coli porin OmpF in reconstituted membranes. In addition, a blindly ending pore exists which appears to be connected to the continuous pores via small channels. The significance of the regularly arrayed porin cylinders with respect to the shape and function of the stalks is discussed.