Crystal Structure of Osmoporin OmpC from E. coli at 2.0 Å

Structural basis for solute transport, nucleotide regulation, and immunological recognition of Neisseria meningitidis PorB

“…1 B and C) identifies a putative pathway on the pore face nearest the crystallographic 3-fold axis that is lined with positively charged residues. A similar feature has been identified in the Escherichia coli OmpF (34,35), the Delfita acidovorans Omp32 (36,37), and the E. coli OmpC (38), which all share structural similarity to PorB in the transmembrane β-barrel region of the protein (SI Text and Fig. S3 A-C).…”

The porin and the permeating antibiotic: a selective diffusion barrier in Gram-negative bacteria

“…The strength of the ion flux under different conditions (salt, concentration, pH and external voltage) will reflect the channel's structure and functional properties, such as ion selectivity (for example, the ratio of potassium to chloride permeability). Conductance measurements suggest that OmpF and OmpC have a pore size of almost 1 nm, and this was confirmed by high-resolution structure analyses 66,67 . Addition of antibiotics or sugar molecules on one (or both) side of the bilayer causes them to diffuse towards the channel.…”

“…In the pore constriction area (eyelet region), various mutagenesis and electrophysiological studies have focused on the positive cluster (Lys16, Arg42, Arg82 and Arg132) and the negative face (Asp113, Glu117 and Asp121), which are important for the electrostatic field that governs the diffusion of charged molecules 9,10 . The recent 3D structure of OmpC 67 , the major porin that is detected in clinical Gram-negative bacteria, indicates that the general organization of the channel is well conserved between OmpF and OmpC, except that the respective pore lining is altered at the extracellular entrance 66,67 (located just before the constriction region). The comparison between OmpF, OmpC activity and the solved structure of the major Klebsiella pneumoniae porin 92 , OmpK36, defines the two groups of major enterobacterial porins, OmpC-and OmpF-class porins (TABLE 1).…”

“…Two final and most resistant isolates, which were obtained after carbapenem (meropenem and imipenem) treatment, showed a severe reduction in OmpC synthesis compared with the first five isolates 47 . In addition, the few OmpC porins that were produced by these two isolates harboured an additional R124H substitution in the region that lines the pore, which causes an alteration in the arg cluster positioned in the pore eyelet 67 .…”

“…High-resolution structures are now available for some bacterial porins, including OmpF and, more recently, OmpC 66,67 . Inspection of the porin structure suggests that the permeation of molecules through the channel is driven by molecular interactions with the surface rather than by free diffusion 68,69 .…”