Pneumococcal surface adhesin A (PsaA) (PsaA)

Pneumococcal surface adhesin A (PsaA) is a 37-kDa metal-binding lipoprotein and a member of the LraI protein family, essential for the virulence of Streptococcus pneumoniae (UniProt: P0A4G2). It functions as the substrate-binding protein for the PsaABC ATP-binding cassette (ABC) transporter, which is the primary system for high-affinity manganese (Mn2+) uptake in the pathogen (McAllister et al., 2004, J. Biol. Chem.). Manganese is a vital cofactor for the pneumococcal superoxide dismutase (SodA), which allows the bacteria to neutralize reactive oxygen species and survive the host's oxidative burst (Couñago et al., 2014, Structure). Additionally, PsaA acts as an adhesin, mediating the attachment of the bacteria to E-cadherin on human nasopharyngeal epithelial cells, a critical step for colonization (Rajam et al., 2008, Crit. Rev. Microbiol.). Due to its high conservation across nearly all known pneumococcal serotypes, PsaA is a leading candidate for next-generation, serotype-independent protein vaccines (Luo et al., 2012, Vaccine). Therapeutic strategies focusing on PsaA typically involve the induction of neutralizing antibodies that block bacterial colonization and impair the pathogen's ability to survive oxidative stress.

Other names

Manganese-binding lipoprotein PsaA37 kDa surface antigenLraI family proteinPneumococcal surface antigen A

Induction of antibodies that inhibit bacterial adhesion to host cells and disrupt manganese acquisition, leading to reduced bacterial fitness and clearance.