SIC (streptococcal inhibitor of complement) is a 31 kDa protein secreted by a few highly virulent strains of GAS (group A streptococci), predominantly by the M1 strain. Initially described as an inhibitor of the membrane attack complex of complement, it has turned out to be a polyfunctional inhibitor of the innate mucosal immune response. The SIC protein sequence contains three domains: an N-terminal SRR (short repeat region), followed by three longer tandem repeats [LRR (long repeat region)] and a C-terminal PRR (proline-rich region). SIC inhibits the antibacterial activity of a wide range of antimicrobial peptides and proteins: i.e. lysozyme, SLPI (secretory leucocyte proteinase inhibitor), LL-37, hNP-1 (human neutrophil peptide-1) and the human β-defensins 1, 2 and 3. Analysis of the functional properties of recombinant domains of SIC shows that binding and inhibition of lysozyme and human β-defensin-3 require the SRR+LRR, as does binding to SLPI. Complement inhibition is confined to the SRR. M12 GAS secrete a protein ‘distantly related to SIC’ (DRS). DRS contains a C-terminal PRR which is significantly similar to that of SIC, but it has no central LRR and the N-terminal SRR is very different. DRS inhibits human β-defensin-3, but has no effect on lysozyme, SLPI or complement.
Skip Nav Destination
Article navigation
April 2006
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
Conference Article|
March 20 2006
Inhibition of antimicrobial peptides by group A streptococci: SIC and DRS
B.A. Fernie-King;
B.A. Fernie-King
1Microbial Immunology Group, Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, U.K.
Search for other works by this author on:
D.J. Seilly;
D.J. Seilly
1Microbial Immunology Group, Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, U.K.
Search for other works by this author on:
P.J. Lachmann
P.J. Lachmann
1
1Microbial Immunology Group, Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, U.K.
1To whom correspondence should be addressed (email pjl1000@cam.ac.uk).
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
November 21 2005
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2006 The Biochemical Society
2006
Biochem Soc Trans (2006) 34 (2): 273–275.
Article history
Received:
November 21 2005
Citation
B.A. Fernie-King, D.J. Seilly, P.J. Lachmann; Inhibition of antimicrobial peptides by group A streptococci: SIC and DRS. Biochem Soc Trans 1 April 2006; 34 (2): 273–275. doi: https://doi.org/10.1042/BST0340273
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Captcha Validation Error. Please try again.