Invasive M1T1 group A Streptococcus undergoes a phase‐shift in vivo to prevent proteolytic degradation of multiple virulence factors by SpeB

Abstract

SummaryA globally disseminated strain of M1T1 group A Streptococcus (GAS) has been associated with severe infections in humans including necrotizing fasciitis and toxic shock syndrome. Recent clinicoepidemiologic data showed a striking inverse relationship between disease severity and the degree to which M1T1 GAS express the streptococcal cysteine protease, SpeB. Electrophoretic 2-D gel analysis of the secreted M1T1 proteome, coupled with MALDI-TOF mass spectroscopy, revealed that expression of active SpeB caused the degradation of the vast majority of secreted GAS proteins, including several known virulence factors. Injection of a SpeB + + + +

Conserved anchorless surface proteins as group A streptococcal vaccine candidates

“…The S. pyogenes strains utilised in this study have been described previously: 5448 (emm1) [8], 5448AP (emm1) [10], HSC5 (emm14) [11], NS88.2 (emm98.1) and NS192 (emm100) [12,13], pM1 (emm1) [14], 2036 (emm6) [15], DSM2071 (emm23) [16], NV-2728 (emm12) (Novartis Vaccines, Sienna, Italy), pL1 (emm54) (M. Batzloff, unpublished), and 20174 (emm3) (M. Kotb, unpublished).…”

“…To identify the major cell wall-associated proteins of invasive M1T1 clonal 5448 S. pyogenes isolate [8] grown in the presence of the cysteine protease inhibitor E64, a two-dimensional (2D) sodium dodecyl sulfatepolyacrylamide gel electrophoresis (PAGE) proteomic analysis of a mutanolysin cell wall extract was performed as previously described [17]. (Table 1) to amplify the genes from GAS strain 5448 for recombinant gene expression and the resultant recombinant proteins purified as described previously for ropA [18].…”

“…Proteomic analysis of GAS cell wall extract was undertaken using isolate 5448, a representative of the globally disseminated M1T1 clonal serotype [8]. The cell wall extract was separated by two-dimensional gel electrophoresis and the landmark proteins identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry.…”

“…These authors also demonstrated considerable cross-protection of the 30-valent vaccine against non-vaccine M serotypes [4]. Recently, a series of independent studies have documented a class of GAS cell wall-associated or secreted metabolic enzymes that contain neither N-terminal leader sequences nor C-terminal cell wall anchors [5][6][7][8][9]. Perhaps because these molecules do not fit common categories of bacterial vaccine antigen, e.g.…”

Streptococcal Mitogenic Exotoxin, SmeZ, Is the Most Susceptible M1T1 Streptococcal Superantigen to Degradation by the Streptococcal Cysteine Protease, SpeB

“…SpeB modifies host proteins like matrix proteins thereby facilitating bacterial invasion, and it can posttranslationally cleave and activate precursors for several cytokines and important components of the coagulation pathway (12,13). However, SpeB can also modify and/or inactivate several important GAS virulence proteins, including the anti-phagocytic M protein, the anti-chemotactic C5a peptidase as well as many secreted virulence proteins (12)(13)(14)(15). The activity of SpeB seems to be specific as certain bacterial proteins resist its proteolytic activity (14).…”