Bacterial glyceraldehyde 3-phosphate dehydrogenase (extracellular form) (GAPDH)

Bacterial glyceraldehyde 3-phosphate dehydrogenase (GAPDH) in Streptococcus species is a prominent example of a moonlighting protein, performing essential metabolic functions intracellularly while acting as a potent virulence factor when localized to the cell surface or secreted [1, 4]. In its extracellular form, often referred to as streptococcal surface dehydrogenase (SDH) or plasmin receptor (Plr), it facilitates bacterial colonization by mediating adherence to host tissues through interactions with receptors like the urokinase plasminogen activator receptor (uPAR) and extracellular matrix components such as fibronectin and laminin [2, 7]. It significantly enhances bacterial invasiveness by capturing host plasminogen and converting it into active plasmin, which provides the pathogen with surface-associated proteolytic activity to degrade host barriers [9, 16]. Furthermore, the protein serves as an immunomodulator by inducing the production of anti-inflammatory cytokines like IL-10 and inhibiting host lysozyme, thereby suppressing the innate immune response [10, 14]. Due to its critical role in pathogenesis across various streptococcal species, including S. pyogenes, S. pneumoniae, and S. agalactiae, it is being actively investigated as a therapeutic target for anti-virulence agents such as monoclonal antibodies and vaccines [3, 12]. However, the high structural homology between bacterial and human GAPDH presents a significant challenge for drug development, necessitating the identification of bacteria-specific epitopes to avoid autoimmune cross-reactivity [12, 15].

Other names

Streptococcal surface dehydrogenaseSDHPlasmin receptorPlrSPy0274gapCAnchorless surface protein

Neutralization of extracellular virulence functions including host cell adhesion, plasminogen recruitment, and immune suppression.