P-fimbrial lectin adhesin (PapG)

P-fimbrial lectin adhesins, primarily the PapG protein, are critical virulence factors located at the distal tips of P-pili (pyelonephritis-associated pili) in uropathogenic Escherichia coli (UPEC) [1, 5]. These adhesins function as lectins that specifically recognize and bind to the Gal(alpha1-4)Gal carbohydrate moiety found in the P-blood group antigens and globoseries glycolipids on host cell surfaces [1, 12]. This interaction is a critical first step in the pathogenesis of upper urinary tract infections, as it allows UPEC to colonize the renal pelvis and kidney parenchyma, leading to acute pyelonephritis [16]. There are three main alleles of PapG (I, II, and III), with PapG-II being the most prevalent in human pyelonephritis cases due to its high affinity for globoside (Gb4) in the human kidney [6]. Beyond adhesion, PapG has been shown to protect the bacteria from neutrophil bactericidal activity, further contributing to its role in immune evasion [7]. Because these adhesins are vital for establishing infection but not for bacterial survival, they are considered prime targets for anti-virulence strategies [14]. Therapeutic approaches include synthetic galabiose-based inhibitors that competitively block the binding site and vaccines like the PapDG subunit vaccine designed to elicit protective antibodies [1, 9]. These anti-adhesive molecules offer a promising alternative to traditional antibiotics, potentially reducing the selective pressure for drug resistance while specifically targeting pathogenic strains [3, 14].

Other names

PapG adhesinP-fimbriae adhesinGal-Gal binding adhesinPyelonephritis-associated pilus G proteinP-pilus adhesinGal(alpha1-4)Gal-specific tip adhesin

Inhibition of bacterial attachment to host uroepithelial cells by competitively binding to Gal(alpha1-4)Gal-containing glycolipid receptors.