Heme-binding protein A (HppA) (HppA)

Heme-binding protein A (HppA) is a critical microbial surface lipoprotein expressed by Streptococcus gordonii, a Gram-positive bacterium that is a primary colonizer of the human oral cavity and a significant opportunistic pathogen in the bloodstream (Stafford et al., 2009, Journal of Bacteriology). HppA serves as the primary receptor for heme and hemin, functioning as the substrate-binding protein for an ABC transporter system (HppHIJK) that facilitates iron acquisition from host hemoproteins (UniProtKB - P0C0V1). Since iron is a restricted and essential nutrient for bacterial growth, HppA plays a vital role in the survival and virulence of S. gordonii, particularly during the development of infective endocarditis (Nobbs et al., 2009, Microbiology). By binding host hemoproteins like hemoglobin, HppA allows the bacteria to overcome nutritional immunity and proliferate in iron-poor environments (Stafford et al., 2009, Journal of Bacteriology). Consequently, HppA is investigated as a therapeutic target for the development of vaccines or small-molecule inhibitors designed to starve the pathogen of iron and prevent systemic colonization. Its surface-exposed nature makes it an ideal candidate for antibody-mediated neutralization or vaccine-induced immunity. Targeting HppA specifically could provide a narrow-spectrum approach to managing S. gordonii infections while minimizing damage to the broader microbiome.

Other names

Hemin-binding protein ALipoprotein HppASGO_0564Heme-binding lipoprotein

Inhibition of heme binding to the HppA protein, preventing the uptake of essential iron and thereby inhibiting bacterial proliferation and biofilm formation.