Epigallocatechin gallate inhibits Streptococcus pneumoniae virulence by simultaneously targeting pneumolysin and sortase A

Abstract

Streptococcus pneumoniae (pneumococcus), the causative agent of several human diseases, possesses numerous virulence factors associated with pneumococcal infection and pathogenesis. Pneumolysin (PLY), an important virulence factor, is a member of the cholesterol‐dependent cytolysin family and has cytolytic activity. Sortase A (SrtA), another crucial pneumococcal virulence determinate, contributes greatly to the anchoring of many virulence‐associated surface proteins to the cell wall. In this study, epigallocatechin gallate (EGCG), a natural compound with little known antipneumococcal activity, was shown to directly inhibit PLY‐mediated haemolysis and cytolysis by blocking the oligomerization of PLY and simultaneously reduce the peptidase activity of SrtA. The biofilm formation, production of neuraminidase A (NanA, the pneumococcal surface protein anchored by SrtA), and bacterial adhesion to human epithelial cells (Hep2) were inhibited effectively when S. pneumoniae D39 was cocultured with EGCG. The results from molecular dynamics simulations and mutational analysis confirmed the interaction of EGCG with PLY and SrtA, and EGCG binds to Glu277, Tyr358, and Arg359 in PLY and Thr169, Lys171, and Phe239 in SrtA. In vivo studies further demonstrated that EGCG protected mice against S. pneumoniae pneumonia. Our results imply that EGCG is an effective inhibitor of both PLY and SrtA and that an antivirulence strategy that directly targets PLY and SrtA using EGCG is a promising therapeutic option for S. pneumoniae pneumonia.

Computational Molecular Docking and X-ray Crystallographic Studies of Catechins in New Drug Design Strategies

“…CMDA and mutational analysis predicted that EGCG binds to Glu277, Tyr358, and Arg359 in PLY and Thr169, Lys171, and Phe239 in SrtA ( Figure 9 ). Since EGCG protected mice against pneumonia by S. pneumoniae , EGCG may be a promising therapeutic option for this disease [ 91 ].…”

“…CMDA predicts the involvement of Ser256, Glu277, Tyr358, and Arg359 in PLY and Thr167, Lys169, and Phe237 in SrtA in the binding to EGCG. Reproduced from [ 91 ] under the terms of the Creative Commons Attribution License (CC BY).…”

Multifaceted Role of Pneumolysin in the Pathogenesis of Myocardial Injury in Community-Acquired Pneumonia

“…The various PLY antagonists identified, none of which was found to possess antimicrobial activity, effectively attenuated the hemolytic activity of PLY, as well as the injurious effects of the toxin on an alveolar epithelial cell line in vitro [ 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 ]. In addition, subcutaneous administration of these various natural antagonists of PLY resulted in significantly improved survival in a murine model of intranasal pneumococcal lung infection [ 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 ]. The various members of each category of natural antagonists of PLY are summarized as follows: phytosterols : β-sitosterol was initially identified as a cholesterol-mimic, interacting with the conserved cholesterol-binding site located on domain 4 of PLY, with potency comparable with that of cholesterol [ 99 ].…”

“…A follow-up, mechanistic study, using a molecular dynamics simulation approach, revealed two additional phytosterols which also antagonized the membrane-binding activity of PLY viz. campesterol and brassicasterol, with the former demonstrating activity comparable with that of β-sitosterol and the latter being somewhat less potent [ 100 ] polyphenols : verbascoside (a caffeoyl polyethanol glycoside) and the catechin, epigallocatechin gallate, are naturally-occurring polyphenol anti-oxidant antagonists of PLY, which have demonstrated almost complete attenuation of the hemolytic activity of the toxin at concentrations of about 2.0 and 2.7 µg/mL respectively [ 101 , 102 ]. Unlike the phytosterols, the polyphenol antagonists appear to interfere with the oligomerization of PLY monomers on the target cell membrane via binding to the cleft between domains 3 and 4 of the toxin molecule [ 101 , 102 ] bioflavonoids : three bioflavonoids viz.…”

“…campesterol and brassicasterol, with the former demonstrating activity comparable with that of β-sitosterol and the latter being somewhat less potent [ 100 ] polyphenols : verbascoside (a caffeoyl polyethanol glycoside) and the catechin, epigallocatechin gallate, are naturally-occurring polyphenol anti-oxidant antagonists of PLY, which have demonstrated almost complete attenuation of the hemolytic activity of the toxin at concentrations of about 2.0 and 2.7 µg/mL respectively [ 101 , 102 ]. Unlike the phytosterols, the polyphenol antagonists appear to interfere with the oligomerization of PLY monomers on the target cell membrane via binding to the cleft between domains 3 and 4 of the toxin molecule [ 101 , 102 ] bioflavonoids : three bioflavonoids viz. apigenin (4′,5,7-trihyddroxyflavone) [ 103 ], morin [2-(2,4-dihydroxyphenol)-3,5,7-trihydroxychromen-4-one] [ 104 ] and amentoflavone {8-[5-(5,7-dihydroxy-4-oxo-chromen-2-yl)-2-hydroxy-phenyl]-5,7-dihydroxy-2-(4-hydroxyphenyl)chromen-4-one} [ 105 ] have also been found to attenuate the harmful activities of PLY.…”