First Zinc-Bound Structures of Calprotectin Show How It Starves Bacteria
Summary: Researchers have determined the first zinc-bound crystal structures of the immune protein calprotectin, showing how it deprives bacteria of essential nutrients. The findings explain how calprotectin inhibits the growth of pathogens such as Staphylococcus aureus by locking up zinc in specialized binding sites, limiting microbial survival and biofilm formation.
Key Highlights:
- Structural insights: Calprotectin captures zinc in two distinct binding sites — a six-histidine (His₆) cage and a His₃Asp site — across its S100A8 and S100A9 subunits.
- Affinity and resilience: Even when histidine residues are altered, calprotectin maintains picomolar zinc affinity, preserving its antimicrobial effect.
- Impact on S. aureus: Blocking zinc availability disrupts bacterial growth and biomass accumulation. Disabling both zinc sites removes this protective effect.
- Role of protein tail: The tail of S100A9 influences bacterial adherence and community structure, further modulating calprotectin’s antimicrobial activity.
- Wound care relevance: As S. aureus is a frequent cause of chronic wound infections, this research highlights potential strategies for enhancing innate immunity or developing zinc-binding biomaterials to reduce infection risk.
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Keywords:
calprotectin,
zinc sequestration,
Staphylococcus aureus,
antimicrobial immunity,
wound infections