1.B.1.1.15
OmpU porin (cation-selective; P_K/P_Cl = 14; bile salt inducible) (low permeability to bile) (Simonet et al., 2003). OmpU influences sensitivities to β-lactam antibiotics and sodium deoxycholate induction of biofilm formation and growth on large sugars (Pagel et al., 2007).   The effective pore radus is 0.55 nm which increases with acidic pH but decreases with increasing ionic strength (Duret and Delcour 2010). OmpU induces target animal cell death after it inserts into host mitochondrial membranes (Gupta et al. 2015). The high resolution structures of OmpT and OmpU, the two major porins in V. cholerae, have been determined, and both have unusual constrictions that create narrower barriers for small-molecule permeation and change the internal electric fields of the channels (Pathania et al. 2018). Vibrio cholerae OmpU activates dendritic cells via TLR2 and the NLRP3 inflammasome (Dhar et al. 2023).  Four conserved domains in OmpU are linked with resistance to bile and host-derived antimicrobial peptides. Mutant strains for these domains exhibit differential susceptibility patterns to these and other antimicrobials. A mutant strain in which the four domains of the clinical allele were exchanged for those of a sensitive strain exhibits a resistance profile closer to a porin deletion mutant. Finally, using phenotypic microarrays, novel functions of OmpU and their connection with allelic variability were uncovered (Grant et al. 2023).