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Friend or foe: the same fold for attack and defense
Natalya Lukoyanova1, Helen R Saibil
1Department of Crystallography and Institute of Structural Molecular Biology, Birkbeck College, London, UK.
Trends in Immunology
|February 6, 2008
Summary
Immune system proteins and bacterial toxins share a common structure and membrane attack mechanism. This discovery reveals unexpected evolutionary links between eukaryotic defense and bacterial cytolysins.
Area of Science:
- Structural biology
- Immunology
- Microbiology
Background:
- The membrane attack complex/perforin (MACPF) domain is crucial for immune defense.
- Bacterial cholesterol-dependent cytolysins (CDCs) are pore-forming toxins.
Purpose of the Study:
- To investigate the structural relationship between MACPF proteins and bacterial CDCs.
- To understand the mechanism of membrane insertion and pore formation.
Main Methods:
- Analysis of recent crystal structures of MACPF domains.
- Comparative structural analysis with bacterial CDCs.
Main Results:
- Unexpected structural similarity found between MACPF domains and bacterial CDCs.
- Shared core fold identified despite lack of sequence homology.
- Common mechanism for membrane insertion and pore formation elucidated.
Conclusions:
- Eukaryotic immune proteins and bacterial toxins utilize a conserved structural fold and mechanism.
- This finding suggests convergent evolution or a shared ancient ancestor.
- Provides new insights into immune defense and bacterial pathogenesis mechanisms.
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