Streptococcal 5'-Nucleotidase A (S5nA), a Novel Streptococcus pyogenes Virulence Factor That Facilitates Immune Evasion.
Lisa ZhengAdrina KhemlaniNatalie LorenzJacelyn Mei San LohRies J LangleyThomas ProftPublished in: The Journal of biological chemistry (2015)
Streptococcus pyogenes is an important human pathogen that causes a wide range of diseases. Using bioinformatics analysis of the complete S. pyogenes strain SF370 genome, we have identified a novel S. pyogenes virulence factor, which we termed streptococcal 5'-nucleotidase A (S5nA). A recombinant form of S5nA hydrolyzed AMP and ADP, but not ATP, to generate the immunomodulatory molecule adenosine. Michaelis-Menten kinetics revealed a Km of 169 μm and a Vmax of 7550 nmol/mg/min for the substrate AMP. Furthermore, recombinant S5nA acted synergistically with S. pyogenes nuclease A to generate macrophage-toxic deoxyadenosine from DNA. The enzyme showed optimal activity between pH 5 and pH 6.5 and between 37 and 47 °C. Like other 5'-nucleotidases, S5nA requires divalent cations and was active in the presence of Mg(2+), Ca(2+), or Mn(2+). However, Zn(2+) inhibited the enzymatic activity. Structural modeling combined with mutational analysis revealed a highly conserved catalytic dyad as well as conserved substrate and cation-binding sites. Recombinant S5nA significantly increased the survival of the non-pathogenic bacterium Lactococcus lactis during a human whole blood killing assay in a dose-dependent manner, suggesting a role as an S. pyogenes virulence factor. In conclusion, we have identified a novel S. pyogenes enzyme with 5'-nucleotidase activity and immune evasion properties.
Keyphrases
- biofilm formation
- escherichia coli
- pseudomonas aeruginosa
- staphylococcus aureus
- endothelial cells
- protein kinase
- antimicrobial resistance
- candida albicans
- cell free
- ionic liquid
- adipose tissue
- risk assessment
- nitric oxide
- hydrogen peroxide
- induced pluripotent stem cells
- single molecule
- high throughput
- heavy metals
- pluripotent stem cells
- free survival
- amino acid
- room temperature
- data analysis