Processing of antimicrobial peptides derived from chromograninA by Staphylococcus aureus virulence factors

Abstract number: P1976

Metz-Boutigue M.H., Shooshtarizadeh P., Chich J.F., Corazzol C., Lefèvre S., Guérold B., Delalande F., Jehl F., Prévost G., Haïkel Y., Aunis D.

Objectives: Recent studies have shown that S. aureus strains produce virulence factors that are proteolytic enzymes able to interact with tissue components and the host defence mechanisms. The antimicrobial peptides play a crucial role in innate immunity and avoidance mechanisms deployed by S. aureus may include proteolytic degradation. The present study is conducted to evaluate the effects of several S. aureus virulence factors against the antimicrobial chromogranin A (CGA)-derived peptides.

Methods: By using a combination of RP-HPLC, Edman sequencing and Maldi-Tof mass spectrometry, we analyzed the processing of Chromofungin (CGA57–66), Catestatin (CGA344–364) and Cateslytin (CGA344–358), three potent antimicrobial CGA-derived peptides, after incubation in presence of two S. aureus supernatants, (S1, a MRSA strain and S2 a strain without resistance against tested antibiotics). A similar experimental strategy was applied to determine the effects of the endoprotease Glu-C of S. aureus on the degradation of CGA-derived peptides released by chromaffin cells during stress. The structure of the new generated peptides was related with the antimicrobial activities against bacteria, fungi, yeasts and Plasmodium.

Results: After incubation with S. aureus S1 or S2 for 18 h, we observed the degradation of Catestatin and we determined the sequence of new generated fragments. The degradation profile was different with both strains and for the strain S2 aureolysin might be involved in the proteolytic process. In contrast, Cateslytin and Chromofungin remained mostly intact after incubation with either strain. Furthermore, when the material released by chromaffin cells was treated by the Glu-C protease from S. aureus, we observed the degradation of numerous antibacterial peptides to generate new antifungal peptides.

Conclusion: We evidence that S. aureus subverts innate immunity to degrade highly conserved antibacterial peptides and to produce new antifungal peptides.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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