1.B.1.1.1
OmpF general porin. OmpF can deliver peptides of >6 KDa (epitopes) including protamine, through the pore lumen from the periplasm to the outside (Housden et al., 2010; Ghale et al. 2014).  For cephalosporin antibiotics, the interaction strength series is ceftriaxone > cefpirome > ceftazidime (Lovelle et al. 2011).  An unfolded protein such as colicin E9 can thread through OmpF from the outside to reach the periplasm (Housden et al. 2013).  Polynucleotides can pass through OmpF (Hadi-Alijanvand and Rouhani 2015). LPS influences the movement of bulk ions (K⁺ and Cl^-), but the ion selectivity of OmpF is mainly affected by bulk ion concentrations (Patel et al. 2016).  OMPs such as OmpF cluster into islands that restrict their lateral mobility, while IMPs generally diffuse throughout the cell. Rassam et al. 2018 demonstrated that when transient, energy-dependent transmembrane connections are formed, IMPs become subjugated by the inherent organisation of OMPs, and that such connections impact IMP function. They showed that while establishing a translocon for import, colicin ColE9 sequesters the IMPs of the proton motive force (PMF)-linked Tol-Pal complex into islands mirroring those of colicin-bound OMPs. Through this imposed organisation, the bacteriocin subverts the outer-membrane stabilizing role of Tol-Pal, blocking its recruitment to cell division sites and slowing membrane constriction. The ordering of IMPs by OMPs via an energised inter-membrane bridge represents an emerging functional paradigm in cell envelope biology (Rassam et al. 2018). Colicin E9 (ColE9) disordered regions exploit OmpF for direction-specific binding, which ensures the constrained presentation of an activating signal within the bacterial periplasm (Housden et al. 2018). Anionic lipid binding can prevent closure of OmpF channels, thereby increasing access of antibiotics that use porin-mediated pathways (Liko et al. 2018). OmpF may be the major route of D-lactate/D-3-hydroxybutyrate oligo-ester secretion (Utsunomia et al. 2017). Lipid Headgroup Charge and Acyl Chain Composition Modulate Closure of the channel (Perini et al. 2019). Piperacillin, tazobactam, ampicillin and sulbactam interact strongly with OmpF, and may be transported (Wang et al. 2019). Gating kinetics are governed by lipid characteristics so that each stage of a sequential closure is different from the previous one, probably because of intra- or intermonomeric rearrangements (Perini et al. 2019). OmpF transports fosfomycin (Golla et al. 2019) and bacteriocins into cells. Polypeptide transport/binding processes generate an essentially irreversible, hook-like assembly that constrains an import activating peptide epitope between two subunits of the OmpF trimer (Lee et al. 2020). Physical properties of bacterial porins (OmpF and OmpC) match environmental conditionsof induction (Milenkovic et al. 2023). Enrofloxacin caused blockage of ion current through OmpF, depending on the side of addition to the assymetic bilayer containing lipopolysaccharide and the transmembrane voltage applied (Donoghue et al. 2023). OmpF homologs are OmpK35 of Klebsiella pneumoniae and OmpE35 of Enterobacteria cloacae, and these porins transport ciprofloxacin (Acharya et al. 2024).