Proteolytic degradation of human antimicrobial peptide LL-37 by Bacillus anthracis may contribute to virulence.
Thwaite. Joanne E JE; Hibbs. Stephen S; Titball. Richard W RW; Atkins. Timothy P TP
Key Findings
- B. subtilis is mildly sensitive to LL‑37, while B. cereus and B. thuringiensis have moderate resistance.
- B. anthracis shows the highest resistance and can degrade LL‑37 using extracellular metalloproteases.
- Metalloprotease inhibitors like EDTA block LL‑37 degradation, and the responsible protease gene is chromosomal, not on a plasmid.
Practical Outcomes
- If you’re considering LL‑37 supplements or therapies, be aware that some bacteria, especially B. anthracis, can neutralize it with proteases. Co‑using metalloprotease inhibitors might preserve LL‑37 activity, but this is more of a research insight than a ready‑to‑use protocol for most biohackers.
Summary
The study shows that the human antimicrobial peptide LL‑37 is broken down by a protein‑making enzyme from the dangerous bacterium Bacillus anthracis, which makes the bacteria more resistant to LL‑37’s killing effect. Other Bacillus species are less resistant. This suggests that LL‑37’s usefulness could be limited when certain bacteria produce degrading enzymes.
Abstract
In this paper we report on the susceptibilities of a range of Bacillus species to the human antimicrobial peptide LL-37. B. subtilis showed a low level of resistance to killing by LL-37 (50% growth-inhibitory concentration [GI50], 1 microg/ml). B. cereus and B. thuringiensis showed intermediate levels of resistance to killing (GI50s, 33 microg/ml and 37 microg/ml, respectively). B. anthracis showed the highest level of resistance (GI50s, 40 to 66 microg/ml). The degradation of LL-37 by B. anthracis culture supernatant was blocked by the metalloprotease inhibitors EDTA and 1,10-phenanthroline, and the gene encoding the protease responsible for LL-37 degradation was not plasmid borne. Our findings suggest that alongside the classical plasmid-based virulence determinants, extracellular metalloproteases of B. anthracis may play a role in survival in the host.
Study Information
pubmed
2006
10.1128/aac.01488-05