Phosphate-selective porin OmpP (PhoE)

The bacterial PhoE porin is a specialized outer membrane protein found in Gram-negative bacteria, such as Escherichia coli, where it functions as a trimeric channel. It is specifically induced under phosphate-starvation conditions to facilitate the uptake of inorganic phosphate and other anionic nutrients through the outer membrane. Structurally, each monomer consists of a 16-stranded beta-barrel that forms a water-filled pore with a distinct preference for negatively charged solutes due to a cluster of lysine residues in its constriction loop. In the context of pharmacology, PhoE is a critical pathway for the entry of various anionic antibiotics, including certain cephalosporins and carbapenems, into the bacterial cell. Mutations that lead to the loss or modification of PhoE can significantly decrease bacterial susceptibility to these drugs, making it a key factor in the development of antimicrobial resistance. Understanding the structural and functional properties of the PhoE trimer is essential for designing new antibiotics that can effectively bypass or utilize these channels to reach their intracellular targets.

Other names

Phosphonate-selective porinOuter membrane pore protein EPhosphoporinPhoE porinBacterial PhoE porin trimer

PhoE acts as a passive diffusion channel that facilitates the entry of anionic antibiotics, such as certain beta-lactams, into the periplasmic space of Gram-negative bacteria. While not a primary drug target in the sense of inhibition, its presence and permeability are critical for the efficacy of these antibiotics, and its downregulation is a known mechanism of bacterial drug resistance.