The 5’-nucleotidase S5nA is dispensable for evasion of phagocytosis and biofilm formation in Streptococcus pyogenes

Abstract

5’-nucleotidases are widespread among all domains of life. The enzymes hydrolyze phosphate residues from nucleotides and nucleotide derivatives. In some pathobiontic bacteria, 5’-nucleotidases contribute to immune evasion by dephosphorylating adenosine mono-, di-, or tri-phosphates, thereby either decreasing the concentration of pro-inflammatory ATP or increasing the concentration of anti-inflammatory adenosine, both acting on purinergic receptors of phagocytic cells. The strict human pathogen Streptococcus pyogenes expresses a surface-associated 5’-nucleotidase (S5nA) under infection conditions that has previously been discussed as a potential virulence factor. Here we show that deletion of the S5nA gene does not significantly affect growth in human blood, evasion of phagocytosis by neutrophils, formation of biofilms and virulence in an infection model with larvae of the greater wax moth Galleria mellonella in S. pyogenes serotypes M6, M18 and M49. Hence, the surface-associated 5’-nucleotidase S5nA seems dispensable for evasion of phagocytosis and biofilm formation in S. pyogenes.

Cell wall‐anchored 5′‐nucleotidases in Gram‐positive cocci

“…Addition of purified recombinant S5nA significantly reduced bacterial killing in a dose‐dependent manner where 1 µM rS5nA almost completely abolished killing of the L. lactis bacteria (Zheng et al, ). More recently, the role of S5nA in immune evasion was questioned when it was demonstrated that deletion of the s5nA gene in S. pyogenes had no effect on growth in human blood, evasion of phagocytosis by neutrophils, formation of biofilms and virulence in a Galleria mellonella (great wax moth) larvae infection model (Dangel et al, ). The difference between the two studies is the use of recombinant S5nA in combination with a non‐virulent bacterium instead of a S. pyogenes deletion mutant where the loss of s5nA might be compensated by the large arsenal of virulence factors produced by this species.…”

Studies of Streptococcus anginosus Virulence in Dictyostelium discoideum and Galleria mellonella Models

“…Furthermore, CcpA directly regulates the expression of toxins like streptolysin and intermedilysin by Streptococcus pyogenes and S. intermedius , respectively ( 42 , 69 , 70 ). Similarly, the application of the G. mellonella model to the S. anginosus study opens up the possibility of comparing S. anginosus with other streptococci, as in its previous use to examine S. pneumoniae ( 48 , 50 ), Streptococcus agalactiae ( 71 , 72 ), S. pyogenes ( 46 , 47 , 73 , 74 ), and Streptococcus mutans ( 75 , 76 ). A clear example is that our histological analysis revealed robust activation of immune defenses, which in some cases correlated with tissue damage, a common phenomenon associated with group A streptococcus infection ( 47 ).…”

Immunomodulating Enzymes from Streptococcus pyogenes—In Pathogenesis, as Biotechnological Tools, and as Biological Drugs

“…Intriguingly, S5nA and SpnA have been demonstrated to generate inorganic phosphate from DNA, suggesting that these two enzymes cause a so-called “double-hit” to the host’s innate immune response by destroying NETs and killing macrophages via generation of dAdo [ 74 ], as has been described in S. sanguinis [ 77 ]. It has, however, further been demonstrated that S5nA does not significantly affect streptococcal growth in human blood, evasion of phagocytosis, or the formation of biofilm [ 78 ], suggesting that the main role of S5nA in streptococcal pathogenesis is indeed the destruction of macrophages.…”

“…Although the exact role of SpnA in the pathogenesis of S. pyogenes is still unclear, both blood bactericidal assays and mouse infection models demonstrate that the SpnA knockout strain is less virulent than the parental strain [ 72 ]. Whereas both Sda1 and SpnA promote streptococcal survival in whole blood [ 66 , 67 ], the opposite is true for the streptococcal nucleotidase S5nA [ 78 ].…”