Deciphering Key Residues Involved in the Virulence-promoting Interactions between Streptococcus pneumoniae and Human Plasminogen

• Published in: The Journal of biological chemistry 2017-02, Vol.292 (6), p.2217-2225
• Main Authors: Moreau, Christophe, Terrasse, Rémi, Thielens, Nicole M., Vernet, Thierry, Gaboriaud, Christine, Di Guilmi, Anne Marie
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; bacterial pathogenesis; binding site mapping; Biochemistry, Molecular Biology; cell surface receptor; crystal structure; Glyceraldehyde-3-Phosphate Dehydrogenases - chemistry; Glyceraldehyde-3-Phosphate Dehydrogenases - metabolism; gram-positive bacteria; host-pathogen interaction; human plasminogen; Humans; Kinetics; Life Sciences; peptide array; plasminogen; Plasminogen - metabolism; pneumococcal GAPDH; Protein Binding; Protein Conformation; Protein Structure and Folding; protein-protein interaction; Streptococcus; Streptococcus pneumoniae - pathogenicity; Structural Biology; Surface Plasmon Resonance; Thermodynamics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M116.764209

Bacterial pathogens recruit circulating proteins to their own surfaces, co-opting the host protein functions as a mechanism of virulence. Particular attention has focused on the binding of plasminogen (Plg) to bacterial surfaces, as it has been shown that this interaction contributes to bacterial adhesion to host cells, invasion of host tissues, and evasion of the immune system. Several bacterial proteins are known to serve as receptors for Plg including glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a cytoplasmic enzyme that appears on the cell surface in this moonlighting role. Although Plg typically binds to these receptors via several lysine-binding domains, the specific interactions that occur have not been documented in all cases. However, identification of the relevant residues could help define strategies for mitigating the virulence of important human pathogens, such as Streptococcus pneumoniae (Sp). To shed light on this question, we have described a combination of peptide-spot array screening, competition and SPR assays, high-resolution crystallography, and mutational analyses to characterize the interaction between SpGAPDH and Plg. We identified three SpGAPDH lysine residues that were instrumental in defining the kinetic and thermodynamic parameters of the interaction. Altogether, the integration of the data presented in this work allows us to propose a structural model for the molecular interaction of the SpGAPDH-Plg complex.