Insertional inactivation of Streptolysin S expression is associated with altered riboflavin metabolism inStreptococcus pyogenes

Liu, Shaoyou; Sela, Shlomo; Cohen, Gerald; Jadoun, Jeris; Cheung, Ambrose L.; Ofek, Itzhak

doi:10.1006/mpat.1996.0107

Cited by 18 publications

(8 citation statements)

References 32 publications

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“…These observations, in combination with the predicted cytoplasmic localization of SagB (38), support the hypothesis that these conserved regions in SagB are involved in FMN binding and that SagB contributes to the chemical modification of SagA. Liu et al reported elimination of SLS activity in a transposon Tn916 mutant of GAS deficient in riboflavin biosynthesis (34). Considering that FMN is a direct product of riboflavin metabolism, a requirement for FMN would provide the link between SLS activity and riboflavin biosynthesis.…”

Section: Discussionmentioning

confidence: 58%

“…The remaining gene products of the operon are contiguously aligned (sagB to sagI) and are considered important for the processing and transport of SagA. In addition, while the GAS sag operon is both necessary and sufficient for SLS production, there is evidence that sagA may also possess a regulatory function affecting the expression of SLS and other GAS virulence factors through a complex mechanism (6,32,34). The discovery of an SLS homologue in S. iniae adds to a small list of streptococcal pathogens harboring a version of this potent exotoxin.…”

Section: Discussionmentioning

confidence: 99%

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Identification of a Streptolysin S-Associated Gene Cluster and Its Role in the Pathogenesis ofStreptococcus iniaeDisease

et al. 2002

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. S. iniae produces a cytolysin that confers a hemolytic phenotype on blood agar media. In this study, we characterized the genomic region responsible for S. iniae cytolysin production and assessed its contribution to virulence. Transposon (Tn917) mutant libraries of commensal and disease-associated S. iniae strains were generated and screened for loss of hemolytic activity. Analysis of two nonhemolytic mutants identified a chromosomal locus comprising 9 genes with 73% homology to the group A streptococcus (GAS) sag operon for streptolysin S (SLS) biosynthesis. Confirmation that the S. iniae cytolysin is a functional homologue of SLS was achieved by PCR ligation mutagenesis, complementation of an SLS-negative GAS mutant, and use of the SLS inhibitor trypan blue. SLS-negative sagB mutants were compared to their wild-type S. iniae parent strains in the murine model and in human whole-blood killing assays. These studies demonstrated that S. iniae SLS expression is required for local tissue necrosis but does not contribute to the establishment of bacteremia or to resistance to phagocytic clearance.

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Section: Discussionmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 99%

Identification of a Streptolysin S-Associated Gene Cluster and Its Role in the Pathogenesis ofStreptococcus iniaeDisease

et al. 2002

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“…In an M12 strain, a Tn916 insertion mutant that lacked SLS activity had wild-type levels of both M and T antigen (39). In an M3 strain, inactivation of SLS by a Tn916 insertion was associated with an altered growth requirement, but M protein was not affected (30). Unfortunately, in both cases, the locations of the Tn916 insertions were not mapped and thus the reduction of SLS activity may have been an indirect effect of insertion in some unknown regulatory locus.…”

Section: Discussionmentioning

confidence: 99%

Generation and Surface Localization of Intact M Protein inStreptococcus pyogenesAre Dependent onsagA

et al. 2001

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The M protein is an important surface-located virulence factor of Streptococcus pyogenes, the group A streptococcus (GAS). Expression of M protein is primarily controlled by Mga, a transcriptional activator protein. A recent report suggested that the sag locus, which includes nine genes necessary and sufficient for production of streptolysin S, another GAS virulence factor, is also needed for transcription of emm, encoding the M protein (Z. Li, D. D. Sledjeski, B. Kreikemeyer, A. Podbielski, and M. D. Boyle, J. Bacteriol. 181:6019-6027, 1999). To investigate this in more detail, we constructed an insertion-deletion mutation in sagA, the first gene in the sag locus, in the M6 strain JRS4. The resulting strain, JRS470, produced no detectable streptolysin S and showed a drastic reduction in cell surface-associated M protein, as measured by cell aggregation and Western blot analysis. However, transcription of the emm gene was unaffected by the sagA mutation. Detailed analysis with monoclonal antibodies and an antipeptide antibody showed that the M protein in the sagA mutant strain was truncated so that it lacks the C-repeat region and the C-terminal domain required for anchoring it to the cell surface. This truncated M protein was largely found, as expected, in the culture supernatant. Lack of surface-located M protein made the sagA mutant strain susceptible to phagocytosis. Thus, although sagA does not affect transcription of the M6 protein gene, it is needed for the surface localization of this important virulence factor. Streptococcus pyogenes (the group A streptococcus [GAS]) is a serious human pathogen capable of producing a wide variety of diseases. Such infections range from mild suppurative diseases, such as pharyngitis and pyoderma, to more severe and life-threatening invasive diseases, including myositis, necrotizing fasciitis, and the recently recognized and often fatal streptococcal toxic shock syndrome (for a recent review, see reference 11). The primary infections may also lead to serious sequelae such as acute rheumatic fever, glomerulonephritis, and reactive arthritis (6). It appears that many GAS strains can cause more than one of these diseases.Different strains of GAS produce various virulence factors that are involved in the survival and persistence of this organism within its host. Among them, M protein, which appears as hair-like projections on the cell surface (52), is considered to be a major virulence factor. Probably the most important role of M protein in the virulence of the GAS is that it confers resistance to complement-mediated killing by polymorphonuclear leukocytes and macrophages (27), thus protecting the bacteria from phagocytosis. In addition, M protein is required for attachment of the GAS to keratinocytes and thus is likely to play a critical role in infections initiated at the skin surface. M protein also causes the GAS to aggregate when they attach to tonsillar epithelial cells (9), so it may also play a critical role in initiation of colonization of the respiratory mucosa.The...

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“…SLS was quantified by hemolytic titration assays in the presence and absence of 25 g of trypan blue/ml or 0.5 mg of cholesterol/ml essentially as described elsewhere (25).…”

Section: Methodsmentioning

confidence: 99%

Combined Contributions of Streptolysin O and Streptolysin S to Virulence of Serotype M5Streptococcus pyogenesStrain Manfredo

2003

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Streptolysin O (SLO) and streptolysin S (SLS) are potent cytolytic toxins produced by almost all clinical isolates of group A streptococci (GAS). Allele-replacement mutagenesis was used to construct nonpolar (in-frame) deletion mutations in the slo and sagB genes of the serotype M5 GAS strain Manfredo, producing isogenic single and double SLO-and SLS-defective mutants. In contrast to recent reports on SLS-defective insertion mutants ( Streptococcus pyogenes (group A streptococci [GAS]) is a highly versatile pathogen that causes a wide variety of important human diseases (55). These range in severity from selflimiting infections of the pharynx and skin to rapidly fulminating streptococcal toxic shock syndrome or devastating tissue infections, such as rapidly spreading myositis or necrotizing fasciitis (5, 55). GAS infections can also lead to serious poststreptococcal sequelae, such as acute glomerulonephritis or acute rheumatic fever (55). This versatility reflects, in part, differences in the abilities of strains to produce a wide range of known or suspected virulence factors. However, some virulence factors are highly conserved and expressed by almost all GAS strains. These include the potent cytolytic toxins streptolysin O (SLO) and streptolysin S (SLS) (2,35,36,51).SLO is a 540-amino-acid secreted protein toxin that binds to cholesterol in eukaryotic cell membranes, where it oligomerizes to produce large transmembrane pores leading to cell lysis (40). Sublytic concentrations of SLO have a wide variety of more subtle effects on target cells in vitro (8,9,29,46,50). In laboratory animals, intravenous (i.v.) administration of small quantities of purified SLO (Ͻ0.2 g in mice) causes death within 2 to 3 min, with cardiotoxicity being the prominent pathophysiological effect (1). Sublethal doses have been reported to have various effects on other tissues, including neurological effects, increased capillary permeability, and dermal necrosis in rabbits (1). Despite these highly potent in vitro and in vivo activities, the first direct studies on the role of SLO during an infection recently revealed that SLO contributed to a surprisingly limited extent to GAS virulence in a murine dermonecrosis-invasive infection model (24). No differences were observed in the abilities of a serotype M3 GAS strain and an isogenic slo mutant derivative to cause weight loss 24 h postinfection or induce necrotic lesions in this model, although SLO did contribute to later stages of infection, producing a significant, albeit small, difference in survival rates (24).SLS also has very potent cytolytic activity against a wide range of cells in vitro and produces a variety of more subtle effects at sublytic concentrations (1,16,17,37). Early studies showed that SLS is a nonimmunogenic peptide that loses activity upon separation from various "carrier" molecules (17, 58). However, its precise molecular nature remained an enigma until recent analysis of an SLS-defective transposon Tn916 insertion mutant identified an operon of nine SLSassociated ge...

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Insertional inactivation of Streptolysin S expression is associated with altered riboflavin metabolism inStreptococcus pyogenes

Cited by 18 publications

References 32 publications

Identification of a Streptolysin S-Associated Gene Cluster and Its Role in the Pathogenesis ofStreptococcus iniaeDisease

Identification of a Streptolysin S-Associated Gene Cluster and Its Role in the Pathogenesis ofStreptococcus iniaeDisease

Generation and Surface Localization of Intact M Protein inStreptococcus pyogenesAre Dependent onsagA

Combined Contributions of Streptolysin O and Streptolysin S to Virulence of Serotype M5Streptococcus pyogenesStrain Manfredo

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