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Interaction of Naja naja atra cardiotoxin 3 with H-trisaccharide modulates its hemolytic activity and
Pei-Hsiu Kao1, Shinne-Ren Lin, Long-Sen Chang
1Institute of Biomedical Sciences, National Sun Yat-Sen University-Kaohsiung Medical University Joint Research Center, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
Insights
The H-antigen on blood group O red blood cells (RBCs) reduces the hemolytic activity of Naja naja atra cardiotoxin 3 (CTX3). This interaction alters CTX3
Area of Science:
- Biochemistry
- Toxicology
- Immunology
Background:
- Cardiotoxins (CTXs) from Naja naja atra snake venom exhibit hemolytic activity.
- Blood group antigens, specifically saccharide moieties, may influence the interaction of toxins with cell membranes.
Purpose of the Study:
- To investigate if blood group A, B, and O antigen saccharides modulate the hemolytic activity of Naja naja atra cardiotoxins (CTXs).
- To determine the specific role of the H-antigen in the hemolytic potency of CTX3.
Main Methods:
- Comparative analysis of CTX3 hemolytic activity against cholesterol-depleted red blood cells (RBCs) of blood groups A, B, and O.
- Enzymatic treatment of blood group B RBCs to convert them to blood group O using alpha-galactosidase.
- Pre-incubation of CTX3 with H-trisaccharide.
- Circular dichroism (CD) spectroscopy and self-quenching studies to assess CTX3 conformation and oligomerization.
Main Results:
- CTX3 displayed significantly lower hemolytic activity against blood group O RBCs compared to blood groups A and B.
- Conversion of blood group B RBCs to blood group O attenuated CTX3's hemolytic activity, implicating the H-antigen.
- H-trisaccharide pre-incubation reduced CTX3's hemolytic and membrane-damaging activities.
- CTX3 exhibited enhanced binding affinity for H-trisaccharide compared to other CTXs.
- Binding with H-trisaccharide induced conformational changes in CTX3 and affected its oligomerization.
Conclusions:
- The H-antigen present on blood group O RBCs directly interacts with CTX3.
- This binding alters the membrane-bound conformation and oligomerization of CTX3.
- Consequently, the hemolytic activity of CTX3 against blood group O RBCs is reduced.
Abstract:
To address whether saccharide moieties of blood groups A, B and O antigens modulate hemolytic activity of Naja naja atra cardiotoxins (CTXs), the present study was carried out. Unlike other CTX isotoxins, hemolytic activity of CTX3 toward blood group O cholesterol-depleted red blood cells (RBCs) was notably lower than that of blood groups A and B cholesterol-depleted RBCs. Conversion of blood group B RBCs into blood group O RBCs by alpha-galactosidase treatment attenuated the susceptibility for hemolytic activity of CTX3, suggesting that H-antigen affected hemolytic potency of CTX3. Pre-incubation with H-trisaccharide reduced hemolytic activity and membrane-damaging activity of CTX3. Moreover, CTX3 showed a higher binding capability with H-trisaccharide than other CTXs did. CD spectra showed that the binding with H-trisaccharide induced changes in gross conformation of CTX3. Self-quenching studies revealed that oligomerization of CTX3 was affected in the presence of H-trisaccharide. Taken together, our data suggest that the binding of CTX3 with H-antigen alters its membrane-bound mode, thus reducing its hemolytic activity toward blood group O cholesterol-depleted RBCs.
