Streptolysin

Source: Wikipedia, the free encyclopedia.
Streptolysin O
Identifiers
OrganismStreptococcus pyogenes serotype M1
Symbolslo
UniProt
P0C0I3
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StructuresSwiss-model
DomainsInterPro
Streptolysin S
Identifiers
OrganismStreptococcus pyogenes serotype M4 (strain MGAS10750)
SymbolsagA
UniProt
Q1J7I0
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StructuresSwiss-model
DomainsInterPro

Streptolysins are two

homogenous exotoxins from Streptococcus pyogenes.[1][2] Types include streptolysin O (SLO; slo), which is oxygen-labile, and streptolysin S (SLS; sagA), which is oxygen-stable.[3]

SLO is part of the

antistreptolysin O titre
.

SLS is stable in the presence of oxygen. It is not antigenic due to its small size. It is sometimes considered a bacteriocin due to similarities in the synthesis pathway.[5]

Streptolysin O

Streptolysin O (SLO; slo), is a bacterial toxin that has four

Thiol-activated cytolysin or CDCs. In order for Streptolysin O to work effectively, it needs a significant amount of cholesterol to be present in the target membrane. Unlike other Cholesterol-dependent cytolysins, SLO contains a 60 Amino acid
N-terminal domain that makes it easier to identify.

C. difficile toxins.[7]

This toxin contains highly antigenic effects which causes it to produce the antibody anti-streptolysin O. Clinically, the presence of these antibodies can indicate a recent Group A streptococcal infection. Streptolysin O is also known to facilitate apoptosis in Keratinocytes. It is able to do this by translocating NAD+ glycohydrolase (SPN) across the target cells membrane. It then removes the N-terminal domain which stops SPN translocation leading to SPN mediated apoptosis.[8]

Group A Streptococcus infections

Group A streptococcal infections are responsible for 517,000 deaths annually across the world. Not much is known about the exact mechanism of action in natural infections however, once the infection is present within the cells it can cause devastating effects. When tested in human endometrium cells, 50% of the cells were killed within the first two hours as a result of processes stimulated by Streptolysin O and SpeB proteases. It has also been observed that both Steptolysin O and SpeB protease limit the innate immune response.[9]

Streptolysin S

Streptolysin S (SLS; sagA), is a cytolytic virulence factor which is a member of the thiazole/oxadole-modified microcin (TOMM) family. This cytolysin is a post-translationally modified peptide was synthesized through a natural evolutionary pathway. SLS is responsible for Streptococcus pyogenes' β-hemolytic appearance when grown on blood agar plates. Its biosynthesis is not fully known; however, it is a critical virulence factor for Streptococcus pyogenes infections.[10] SLS brings about its virulence by damaging soft tissue and it can also act as a signaling molecule. When introduced to a host it will affect its phagocytes and also help to introduce GAS across the skin barrier.[11]

References

  1. ^ "streptolysin" at Dorland's Medical Dictionary
  2. ^ Streptolysin at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
  3. PMID 12496195
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  4. PMID 10620666
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  5. PMID 18375757
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  6. PMID 10563803
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  7. PMID 33363530
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  8. ISBN 978-0-12-397169-2
    .
  9. PMID 33320843
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  10. PMID 25668590
    .
  11. PMID 21822292
    .
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