The crystal structure of a post-translationally modified form of eosinophil-derived neurotoxin (EDN) with four extra residues on its N terminus ((-4)EDN) has been solved and refined at atomic resolution (1 A). Two of the extra residues can be placed unambiguously, while the density corresponding to two others is poor ...
The crystal structure of a post-translationally modified form of eosinophil-derived neurotoxin (EDN) with four extra residues on its N terminus ((-4)EDN) has been solved and refined at atomic resolution (1 A). Two of the extra residues can be placed unambiguously, while the density corresponding to two others is poor. The modified N terminus appears to influence the position of the catalytically important His129, possibly explaining the diminished catalytic activity of this variant. However, (-4)EDN has been shown to be cytotoxic to a Kaposi's sarcoma tumor cell line and other endothelial cell lines. Analysis of the structure and function suggests that the reason for cytotoxicity is most likely due to cellular recognition by the N-terminal extension, since the intrinsic activity of the enzyme is not sufficient for cytotoxicity and the N-terminal extension does not affect the conformation of EDN.
Organizational Affiliation:
Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702, USA.
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