Peptostreptococcal albumin-binding protein (PAB)

Peptostreptococcal albumin-binding protein (PAB) is a cell-surface protein expressed by the anaerobic bacterium *Finegoldia magna* (formerly *Peptostreptococcus magnus*)[2][3]. The protein contains a **GA module**, a 53-amino acid domain composed of a left-handed three-helix bundle structure that binds human serum albumin with strong affinity[2][5]. PAB functions as a virulence factor, enabling the bacterium to bind and coat itself with host albumin, thereby camouflaging itself from immune detection and potentially scavenging protein-bound nutrients[3][4]. The albumin-binding site is located on domain II of the human serum albumin molecule and involves residues primarily in the second helix and surrounding loops of the GA module[2][3]. *Finegoldia magna* strains expressing PAB show increased growth rates and virulence compared to non-expressing strains, and the protein's host specificity reflects the narrow host range of this anaerobic bacterium[4]. While structurally similar to streptococcal protein G, which has broader species specificity, PAB represents an interesting evolutionary example of bacterial adaptation to specific host environments[6][7].

Other names

Protein PABFinegoldia magna albumin-binding protein (the organism was formerly known as Peptostreptococcus magnus)GA module-containing protein (refers to its functional domain)

Not applicable — this is a bacterial protein, not a drug target.