Outer membrane protein P6 (P6)

Outer membrane protein P6 (P6) is a highly conserved, 16-kDa peptidoglycan-associated lipoprotein found in both encapsulated and non-typeable Haemophilus influenzae (NTHi) [1, 2]. It serves a vital structural role by anchoring the bacterial outer membrane to the underlying peptidoglycan layer, thereby maintaining the integrity and stability of the cell envelope [1, 6]. P6 is a potent immunogen and a primary target for human bactericidal antibodies, making it a leading candidate for the development of vaccines against NTHi-related conditions such as acute otitis media and chronic obstructive pulmonary disease (COPD) exacerbations [3, 4]. Beyond its structural function, P6 acts as a Toll-like receptor 2 (TLR2) agonist, triggering the release of proinflammatory cytokines like IL-8 and TNF-alpha from host macrophages [5]. While traditionally considered invariant, recent evidence suggests some sequence variation in certain clinical isolates, which is a key consideration for vaccine design [7]. Experimental studies have also explored P6 as a target for small-molecule inhibitors to compromise bacterial cell wall integrity [8].

Other names

Peptidoglycan-associated lipoproteinPAL15 kDa lipoprotein16 kDa lipoproteinompP6OMP P6

Induction of protective bactericidal antibodies and cellular immune responses; structural stabilization of the bacterial cell envelope.