Streptolysin S Carrier Activity of Lipoteichoic Acid

Theodore, Theodore S.; Calandra, Gary B.

doi:10.1016/b978-0-12-640380-0.50030-9

Cited by 10 publications

(8 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although streptolysin O can function independently, streptolysin S requires a carrier to stabilize it in a functional form (19). One of the carriers identified by previous investigators is LTA (18). Such an LTA-streptolysin S complex may place LTA in a position to be exposed to microenvironments rich in Hb before other host components, such as haptoglobin, can sequester it.…”

Section: Vol 75 2007 Notes 2639mentioning

confidence: 99%

Enhancement of Macrophage Stimulation by Lipoteichoic Acid and the Costimulant Hemoglobin Is Dependent on Toll-Like Receptors 2 and 4

2007

View full text Add to dashboard Cite

Macrophage stimulation by lipoteichoic acid (LTA) and hemoglobin (Hb) requires Toll-like receptors 2 and 4 (TLR2 and -4). There are two distinct temporal phases of interleukin-6 (IL-6) production. The first results in a slight enhancement of IL-6 secretion in response to LTA plus Hb compared to that with LTA alone and is TLR4 independent. The second requires TLR4 and accounts for most of the additional stimulation seen with LTA plus Hb.It has been argued that lipoteichoic acid (LTA) is the grampositive counterpart of lipopolysaccharide (LPS) in inducing host responses to infection, including septic shock (6). This concept is based in part on the fact that both molecules stimulate macrophages to secrete proinflammatory cytokines, albeit via different macrophage receptors and signaling pathways (1). It is generally accepted that most kinds of LPS act exclusively through Toll-like receptor 4 (TLR4) (3, 13) and that LTAs activate macrophages through TLR2 (11,14,15,21). Recently, we showed that stimulation of human monocytes and murine macrophages by LTA is markedly enhanced by a costimulatory molecule, namely, hemoglobin (Hb) (7). Hb appeared to form complexes with LTA, which may be responsible for the enhanced activity. In the present study, we found that the enhanced cytokine secretion obtained when macrophages are incubated with LTA-Hb mixtures can be divided into two temporal phases which are dependent upon not only TLR2 but also TLR4.Wild-type TLR4 (HeNC2) and TLR4 mutant (GG2EE) macrophage cell lines, derived from C3H/HeN and C3H/HeJ mice, respectively (4, 8), were used in most of the studies presented here. For incubation with test substances, 2.5 ϫ 10 5 cells were seeded into 24-well plates in macrophage SFM medium (Invitrogen Life Technologies), and after 2 h, the medium was replaced with fresh medium containing test substances at the concentrations indicated. After incubation at 37°C in a humidified 5% CO 2 incubator for the times indicated in the figures, medium samples were removed from triplicate wells and centrifuged to remove detached cells or cellular debris, and supernatants were stored at Ϫ80°C until assay by enzyme-linked immunosorbent assay (ELISA) (for interleukin-6 [IL-6] and tumor necrosis factor alpha [TNF-␣]; eBioscience). In some experiments, resident peritoneal macrophages from TLR4 mutant (C3H/HeJ) and TLR2 Ϫ/Ϫ (B6.129-Tlr2tm1Kir/J; Jackson Laboratory) mice, along with their appropriate wild-type controls (cells from C3H/HeOuJ and C57BL/6J mice, respectively), were used as described previously (7). LTA was purified as described previously (7), and Hb was purchased from Sigma Chemical Co. (St. Louis, MO). The level of endotoxin was determined using the QCL-1000 quantitative chromogenic Limulus amoebocyte lysate assay according to the manufacturer's directions (Bio-Whittaker). In our experiments with LTA, we ruled out the possibility that trace contamination with endotoxin accounted for the responses observed in several different ways. First, the concentrations of LPS detected in our LTA pr...

show abstract

Section: Vol 75 2007 Notes 2639mentioning

confidence: 99%

Enhancement of Macrophage Stimulation by Lipoteichoic Acid and the Costimulant Hemoglobin Is Dependent on Toll-Like Receptors 2 and 4

2007

View full text Add to dashboard Cite

show abstract

“…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 genes (sagA to sagI) which resembles operons encoding modified peptide bacteriocins in other species (4,36,47).…”

mentioning

confidence: 99%

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

2003

View full text Add to dashboard Cite

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...

show abstract

“…Despite detailed investigations over several decades, the exact chemical nature of SLS has remained a great mystery of GAS biology. SLS can exist in intracellular, cell-surface-bound, and extracellular forms (16), but attempts at purification are complicated by instability of the cytolytic activity in the absence of high-molecular-weight carriers, such as yeast RNA core or albumin (47).…”

mentioning

confidence: 99%

Genetic Locus for Streptolysin S Production by Group A Streptococcus

et al. 2000

View full text Add to dashboard Cite

Group A streptococcus (GAS) is an important human pathogen that causes pharyngitis and invasive infections, including necrotizing fasciitis. Streptolysin S (SLS) is the cytolytic factor that creates the zone of betahemolysis surrounding GAS colonies grown on blood agar. We recently reported the discovery of a potential genetic determinant involved in SLS production, sagA, encoding a small peptide of 53 amino acids (S. D. Betschel, S. M. Borgia, N. L. Barg, D. E. Low, and J. C. De Azavedo, Infect. Immun. 66:1671-1679, 1998). Using transposon mutagenesis, chromosomal walking steps, and data from the GAS genome sequencing project (www .genome.ou.edu/strep.html), we have now identified a contiguous nine-gene locus (sagA to sagI) involved in SLS production. The sag locus is conserved among GAS strains regardless of M protein type. Targeted plasmid integrational mutagenesis of each gene in the sag operon resulted in an SLS-negative phenotype. Targeted integrations (i) upstream of the sagA promoter and (ii) downstream of a terminator sequence after sagI did not affect SLS production, establishing the functional boundaries of the operon. A rho-independent terminator sequence between sagA and sagB appears to regulate the amount of sagA transcript produced versus transcript for the entire operon. Reintroduction of the nine-gene sag locus on a plasmid vector restored SLS activity to the nonhemolytic sagA knockout mutant. Finally, heterologous expression of the intact sag operon conferred the SLS beta-hemolytic phenotype to the nonhemolytic Lactococcus lactis. We conclude that gene products of the GAS sag operon are both necessary and sufficient for SLS production. Sequence homologies of sag operon gene products suggest that SLS is related to the bacteriocin family of microbial toxins.Group A streptococcus (GAS), specifically Streptococcus pyogenes, is a common cause of pharyngitis, impetigo, and many other human respiratory tract and soft tissue infections. Recently, there has been a dramatic increase in reports of severe invasive GAS infections, including necrotizing fasciitis and toxic shock syndrome (44). Although GAS produces a wide array of virulence factors, those responsible for the rapid bacterial spread and tissue injury seen with invasive GAS infections are unknown.A hallmark feature of GAS in the clinical laboratory is the zone of beta-hemolysis observed surrounding colonies grown on the surface of blood agar media. The factor responsible for the beta-hemolytic phenotype is streptolysin S (SLS), the oxygen-stable cytolytic toxin of GAS. Despite detailed investigations over several decades, the exact chemical nature of SLS has remained a great mystery of GAS biology. SLS can exist in intracellular, cell-surface-bound, and extracellular forms (16), but attempts at purification are complicated by instability of the cytolytic activity in the absence of high-molecular-weight carriers, such as yeast RNA core or albumin (47).We have adopted a molecular genetic approach towards the identification of SLS and the study of...

show abstract

Streptolysin S Carrier Activity of Lipoteichoic Acid

Cited by 10 publications

References 14 publications

Enhancement of Macrophage Stimulation by Lipoteichoic Acid and the Costimulant Hemoglobin Is Dependent on Toll-Like Receptors 2 and 4

Enhancement of Macrophage Stimulation by Lipoteichoic Acid and the Costimulant Hemoglobin Is Dependent on Toll-Like Receptors 2 and 4

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

Genetic Locus for Streptolysin S Production by Group A Streptococcus

Contact Info

Product

Resources

About