Post-translational tyrosine nitration of eosinophil granule toxins mediated by eosinophil peroxidase.
Nitration of tyrosine residues has been observed during various acute and chronic inflammatory diseases. However, the mechanism of tyrosine nitration and the nature of the proteins that become tyrosine nitrated during inflammation remain unclear. Here we show that eosinophils but not other cell types including neutrophils contain nitrotyrosine-positive proteins in specific granules. Furthermore, we demonstrate that the human eosinophil toxins, eosinophil peroxidase (EPO), major basic protein, eosinophil-derived neurotoxin (EDN) and eosinophil cationic protein (ECP), and the respective murine toxins, are post-translationally modified by nitration at tyrosine residues during cell maturation. High resolution affinity-mass spectrometry identified specific single nitration sites at Tyr349 in EPO and Tyr33 in both ECP and EDN. ECP and EDN crystal structures revealed and EPO structure modeling suggested that the nitrated tyrosine residues in the toxins are surface exposed. Studies in EPO(-/-), gp91phox(-/-), and NOS(-/-) mice revealed that tyrosine nitration of these toxins is mediated by EPO in the presence of hydrogen peroxide and minute amounts of NOx. Tyrosine nitration of eosinophil granule toxins occurs during maturation of eosinophils, independent of inflammation. These results provide evidence that post-translational tyrosine nitration is unique to eosinophils.
Ulrich
Martina
M
Institute of Medical Microbiology and Hygiene, Universitätsklinikum Tübingen, Tübingen 72074, Germany.
Petre
Alina
A
Youhnovski
Nikolay
N
Prömm
Franziska
F
Schirle
Markus
M
Schumm
Michael
M
Pero
Ralph S
RS
Doyle
Alfred
A
Checkel
James
J
Kita
Hirohito
H
Thiyagarajan
Nethaji
N
Acharya
K Ravi
KR
Schmid-Grendelmeier
Peter
P
Simon
Hans-Uwe
HU
Schwarz
Heinz
H
Tsutsui
Masato
M
Shimokawa
Hiroaki
H
Bellon
Gabriel
G
Lee
James J
JJ
Przybylski
Michael
M
Döring
Gerd
G
D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray / Q000379:methods; D047209:Eosinophil Peroxidase / Q000737:chemistry*; D004804:Eosinophils / Q000378:metabolism*; D006801:Humans; D007249:Inflammation; D008168:Lung / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009498:Neurotoxins / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry; D011499:Protein Processing, Post-Translational; D014443:Tyrosine / Q000737:chemistry
D009498:Neurotoxins; D014443:Tyrosine; D047209:Eosinophil Peroxidase; D009584:Nitrogen