The structure of OmpF porin in a tetragonal crystal form.

BACKGROUND OmpF porin is a trimeric integral membrane protein responsible for the passive transport of small hydrophilic molecules, such as nutrients and waste products, across the outer membrane of Escherichia coli. Very few membrane proteins have been crystallized in three dimensions, yet this stable protein can be obtained in several crystal forms. Comparison of the structures of the same membrane protein in two different packing environments is of major interest, because it allows us to explore the integrity of the structure outside the natural membrane environment. RESULTS The structure of OmpF porin in a tetragonal crystal form with two trimers per asymmetric unit has been determined at 3.2 A resolution and compared with that obtained previously in a trigonal crystal form. The lattice contacts involve only polar atoms, whereas extensive hydrophobic protein-protein interactions were found in the trigonal lattice. The trimer structure is virtually identical in both. CONCLUSIONS Our comparison reveals that the overall structure of OmpF is not influenced by crystal lattice constraints and, thus, presumably bears close resemblance to the in vivo structure. The tetragonal crystal structure has provided the starting model for the phasing of neutron diffraction data obtained from this crystal form, as described in an accompanying article.

[1]  J. Rosenbusch,et al.  Detergent structure in tetragonal crystals of OmpF porin. , 1995, Structure.

[2]  J. Jenkins,et al.  X-ray diffraction analysis of matrix porin, an integral membrane protein from Escherichia coli outer membranes. , 1983, Journal of molecular biology.

[3]  J. Rosenbusch,et al.  Secondary structure of a channel‐forming protein: porin from E. coli outer membranes. , 1985, The EMBO journal.

[4]  J. Rosenbusch,et al.  [25] Isolation and crystallization of bacterial porin , 1986 .

[5]  R. Garavito,et al.  The orientation of beta-sheets in porin. A polarized Fourier transform infrared spectroscopic investigation. , 1988, Biophysical journal.

[6]  G. Rummel,et al.  Crystal structures explain functional properties of two E. coli porins , 1992, Nature.

[7]  G. Schulz,et al.  Structure of the membrane channel porin from Rhodopseudomonas blastica at 2.0 Å resolution , 1994, Protein science : a publication of the Protein Society.

[8]  A. Karshikoff,et al.  Electrostatic properties of two porin channels from Escherichia coli. , 1994, Journal of molecular biology.

[9]  R. Read.  Improved Fourier Coefficients for Maps Using Phases from Partial Structures with Errors , 1986 .

[10]  G. Schulz,et al.  The structure of porin from Rhodobacter capsulatus at 1.8 Å resolution , 1991, FEBS letters.

[11]  G. Bricogne,et al.  Methods and programs for direct‐space exploitation of geometric redundancies , 1976 .

[12]  L. K. Buehler,et al.  Plasticity of Escherichia coli porin channels. Dependence of their conductance on strain and lipid environment. , 1991, The Journal of biological chemistry.

[13]  J. Rosenbusch,et al.  Structural transitions of porin, a transmembrane protein , 1984, FEBS letters.

[14]  John R. Helliwell,et al.  Macromolecular Crystallography with Synchrotron Radiation , 1992 .

[15]  J. Rosenbusch,et al.  Matrix protein in planar membranes: clusters of channels in a native environment and their functional reassembly. , 1981, Proceedings of the National Academy of Sciences of the United States of America.

[16]  G. Rummel,et al.  Trigonal crystals of porin from Escherichia coli. , 1991, Journal of molecular biology.

[17]  G. Schulz,et al.  Crystals of an integral membrane protein diffracting to 1.8 A resolution. , 1991, Journal of molecular biology.

[18]  Axel T. Brunger,et al.  Extension of molecular replacement: a new search strategy based on Patterson correlation refinement , 1990 .

[19]  Joshua Jortner,et al.  Transport Through Membranes: Carriers, Channels and Pumps , 1988 .

[20]  J. Jenkins,et al.  Macromolecular crystallography with synchrotron radiation. II. Results , 1983 .

[21]  Crystallization and preliminary X-ray analysis of phosphoporin from the outer membrane of Escherichia coli. , 1991, Journal of molecular biology.

[22]  J. Rosenbusch,et al.  Structural basis for sugar translocation through maltoporin channels at 3.1 A resolution , 1995, Science.

[23]  G. Schulz,et al.  Structure of porin refined at 1.8 A resolution. , 1992, Journal of molecular biology.

[24]  G. Schulz,et al.  Molecular architecture and electrostatic properties of a bacterial porin. , 1991, Science.

[25]  S. Cowan.  Bacterial porins: lessons from three high-resolution structures: Current Opinion in Structural Biology 1993, 3:501–507 , 1993 .

[26]  M. Zulauf,et al.  Neutron Crystallography of a Membrane Protein: Localization of Detergent and Protein at 20-å Resolution. , 1986, Biophysical journal.

[27]  B. Jap,et al.  Biophysics of the structure and function of porins , 1990, Quarterly Reviews of Biophysics.

[28]  Collaborative Computational,et al.  The CCP4 suite: programs for protein crystallography. , 1994, Acta crystallographica. Section D, Biological crystallography.

[29]  J. Thornton,et al.  PROCHECK: a program to check the stereochemical quality of protein structures , 1993 .

[30]  J. Rosenbusch.  Characterization of the major envelope protein from Escherichia coli. Regular arrangement on the peptidoglycan and unusual dodecyl sulfate binding. , 1974, The Journal of biological chemistry.

[31]  T. Wacker,et al.  Crystallization and preliminary X‐ray analysis of porin from Rhodobacter capsulatus , 1989, FEBS letters.

[32]  F. Jähnig,et al.  Models for the structure of outer-membrane proteins of Escherichia coli derived from raman spectroscopy and prediction methods. , 1986, Journal of molecular biology.

[33]  D. Tsernoglou,et al.  A common channel-forming motif in evolutionarily distant porins. , 1991, Journal of structural biology.

[34]  M. Saier,et al.  Transport proteins in bacteria: common themes in their design. , 1992, Science.

[35]  G. Schulz.  Bacterial porins: structure and function. , 1993, Current opinion in cell biology.

[36]  M. Page,et al.  Crystallization and preliminary X-ray characterization of maltoporin from Escherichia coli. , 1990, Journal of molecular biology.