Bacterial outer membrane porins OmpC and PhoE (OmpC/PhoE)

Bacterial outer membrane porins OmpC and PhoE are trimeric beta-barrel proteins essential for the permeability of the Gram-negative bacterial outer membrane, particularly in species like Escherichia coli [1, 2]. OmpC is a non-specific porin that facilitates the passive diffusion of small hydrophilic solutes, including essential nutrients and various classes of antibiotics such as beta-lactams and fluoroquinolones [3, 8]. PhoE is a phosphate-selective porin that is upregulated under phosphate-starvation conditions to specifically transport anions and phosphorylated compounds [16, 18]. These porins are not only vital for nutrient acquisition and osmotic balance but also play significant roles in bacterial pathogenesis, including adhesion to host cells and resistance to acidic environments [10, 12]. In clinical medicine, OmpC and PhoE are critical because they represent the primary entry route for many antimicrobial drugs; thus, their downregulation or mutational alteration is a common mechanism of antibiotic resistance [5, 14]. Furthermore, they are targeted by host innate immune factors like lactoferrin, which can bind and block these channels to exert bactericidal effects [1].

Other names

Outer membrane protein CPhosphate-selective porin OmpPPorin CPorin EOmpCPhoE

These porins serve as passive diffusion channels for the entry of small hydrophilic antibiotics into the bacterial cell. Lactoferrin acts as a blocking agent for OmpC, while the downregulation or mutation of these porins reduces antibiotic influx, leading to antimicrobial resistance [1, 3, 8].