Crystallographic and functional studies of a modified form of eosinophil-derived neurotoxin (EDN) with novel biological activities.
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.
Chang
Changsoo
C
Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702, USA.
Newton
Dianne L
DL
Rybak
Susanna M
SM
Wlodawer
Alexander
A
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D018360:Crystallography, X-Ray; D004727:Endothelium / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D047208:Eosinophil-Derived Neurotoxin; D005455:Fluorescent Antibody Technique; D006801:Humans; D008958:Models, Molecular; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017433:Protein Structure, Secondary; D012259:Ribonuclease, Pancreatic / Q000737:chemistry; D012260:Ribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D012514:Sarcoma, Kaposi / Q000378:metabolism / Q000473:pathology; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured
D047208:Eosinophil-Derived Neurotoxin; D012260:Ribonucleases; D012259:Ribonuclease, Pancreatic; C058703:ranpirnase