Basic amino acid residues of human eosinophil derived neurotoxin essential for glycosaminoglycan binding.
Human eosinophil derived neurotoxin (EDN), a granule protein secreted by activated eosinophils, is a biomarker for asthma in children. EDN belongs to the human RNase A superfamily possessing both ribonucleolytic and antiviral activities. EDN interacts with heparin oligosaccharides and heparin sulfate proteoglycans on bronchial epithelial Beas-2B cells. In this study, we demonstrate that the binding of EDN to cells requires cell surface glycosaminoglycans (GAGs), and the binding strength between EDN and GAGs depends on the sulfation levels of GAGs. Furthermore, in silico computer modeling and in vitro binding assays suggest critical roles for the following basic amino acids located within heparin binding regions (HBRs) of EDN 34QRRCKN39 (HBR1), 65NKTRKN70 (HBR2), and 113NRDQRRD119 (HBR3) and in particular Arg35, Arg36, and Arg38 within HBR1, and Arg114 and Arg117 within HBR3. Our data suggest that sulfated GAGs play a major role in EDN binding, which in turn may be related to the cellular effects of EDN.
Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu 300, Taiwan. dtchang@life.nthu.edu.tw.
Ta-Jen
TJ
Hung
Wei-Tang
WT
Chang
Noboru
N
Tomiya
Yuan-Chuan
YC
Lee
Hao-Teng
HT
Chang
Chien-Jung
CJ
Chen
Ping-Hsueh
PH
Kuo
Tan-chi
TC
Fan
Margaret Dah-Tsyr
MD
Chang
D000595:Amino Acid Sequence; D024361:Amino Acids, Basic / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D047208:Eosinophil-Derived Neurotoxin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004804:Eosinophils / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism*; D006493:Heparin / Q000378:metabolism; D006801:Humans; D058619:Maltose-Binding Proteins / Q000235:genetics / Q000378:metabolism; D062105:Molecular Docking Simulation; D011485:Protein Binding; D017434:Protein Structure, Tertiary
D024361:Amino Acids, Basic; D006025:Glycosaminoglycans; D058619:Maltose-Binding Proteins; D006493:Heparin; D047208:Eosinophil-Derived Neurotoxin