Abstract
High density lipoprotein (HDL) isolated from human atherosclerotic lesions and the blood of patients with established coronary artery disease contains elevated levels of 3-nitrotyrosine and 3-chlorotyrosine. Myeloperoxidase (MPO) is the only known source of 3-chlorotyrosine in humans, indicating that MPO oxidizes HDL in vivo. In the current studies, we used tandem mass spectrometry to identify the major sites of tyrosine oxidation when lipid-free apolipoprotein A-I (apoA-I), the major protein of HDL, was exposed to MPO or peroxynitrite (ONOO-). Tyrosine 192 was the predominant site of both nitration and chlorination by MPO and was also the major site of nitration by ONOO -. Electron paramagnetic spin resonance studies of spin-labeled apoA-I revealed that residue 192 was located in an unusually hydrophilic environment. Moreover, the environment of residue 192 became much more hydrophobic when apoA-I was incorporated into discoidal HDL, and Tyr 192 of HDL-associated apoA-I was a poor substrate for nitration by both myeloperoxidase and ONOO-, suggesting that solvent accessibility accounted in part for the reactivity of Tyr192. The ability of lipid-free apoA-I to facilitate ATP-binding cassette transporter A1 cholesterol transport was greatly reduced after chlorination by MPO. Loss of activity occurred in concert with chlorination of Tyr192. Both ONOO - and MPO nitrated Tyr192 in high yield, but unlike chlorination, nitration minimally affected the ability of apoA-I to promote cholesterol efflux from cells. Our results indicate that Tyr192 is the predominant site of nitration and chlorination when MPO or ONOO- oxidizes lipid-free apoA-I but that only chlorination markedly reduces the cholesterol efflux activity of apoA-I. This impaired biological activity of chlorinated apoA-I suggests that MPO-mediated oxidation of HDL might contribute to the link between inflammation and cardiovascular disease.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 5983-5993 |
| Number of pages | 11 |
| Journal | Journal of Biological Chemistry |
| Volume | 280 |
| Issue number | 7 |
| DOIs | |
| State | Published - Feb 18 2005 |
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ASJC Scopus subject areas
- Biochemistry
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Tyrosine 192 in apolipoprotein A-I is the major site of nitration and chlorination by myeloperoxidase, but only chlorination markedly impairs ABCA1-dependent cholesterol transport. / Shao, Baohai; Bergt, Constanze; Fu, Xiaoyun; Green, Pattie; Voss, John C; Oda, Michael N.; Oram, John F.; Heinecke, Jay W.
In: Journal of Biological Chemistry, Vol. 280, No. 7, 18.02.2005, p. 5983-5993.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Tyrosine 192 in apolipoprotein A-I is the major site of nitration and chlorination by myeloperoxidase, but only chlorination markedly impairs ABCA1-dependent cholesterol transport
AU - Shao, Baohai
AU - Bergt, Constanze
AU - Fu, Xiaoyun
AU - Green, Pattie
AU - Voss, John C
AU - Oda, Michael N.
AU - Oram, John F.
AU - Heinecke, Jay W.
PY - 2005/2/18
Y1 - 2005/2/18
N2 - High density lipoprotein (HDL) isolated from human atherosclerotic lesions and the blood of patients with established coronary artery disease contains elevated levels of 3-nitrotyrosine and 3-chlorotyrosine. Myeloperoxidase (MPO) is the only known source of 3-chlorotyrosine in humans, indicating that MPO oxidizes HDL in vivo. In the current studies, we used tandem mass spectrometry to identify the major sites of tyrosine oxidation when lipid-free apolipoprotein A-I (apoA-I), the major protein of HDL, was exposed to MPO or peroxynitrite (ONOO-). Tyrosine 192 was the predominant site of both nitration and chlorination by MPO and was also the major site of nitration by ONOO -. Electron paramagnetic spin resonance studies of spin-labeled apoA-I revealed that residue 192 was located in an unusually hydrophilic environment. Moreover, the environment of residue 192 became much more hydrophobic when apoA-I was incorporated into discoidal HDL, and Tyr 192 of HDL-associated apoA-I was a poor substrate for nitration by both myeloperoxidase and ONOO-, suggesting that solvent accessibility accounted in part for the reactivity of Tyr192. The ability of lipid-free apoA-I to facilitate ATP-binding cassette transporter A1 cholesterol transport was greatly reduced after chlorination by MPO. Loss of activity occurred in concert with chlorination of Tyr192. Both ONOO - and MPO nitrated Tyr192 in high yield, but unlike chlorination, nitration minimally affected the ability of apoA-I to promote cholesterol efflux from cells. Our results indicate that Tyr192 is the predominant site of nitration and chlorination when MPO or ONOO- oxidizes lipid-free apoA-I but that only chlorination markedly reduces the cholesterol efflux activity of apoA-I. This impaired biological activity of chlorinated apoA-I suggests that MPO-mediated oxidation of HDL might contribute to the link between inflammation and cardiovascular disease.
AB - High density lipoprotein (HDL) isolated from human atherosclerotic lesions and the blood of patients with established coronary artery disease contains elevated levels of 3-nitrotyrosine and 3-chlorotyrosine. Myeloperoxidase (MPO) is the only known source of 3-chlorotyrosine in humans, indicating that MPO oxidizes HDL in vivo. In the current studies, we used tandem mass spectrometry to identify the major sites of tyrosine oxidation when lipid-free apolipoprotein A-I (apoA-I), the major protein of HDL, was exposed to MPO or peroxynitrite (ONOO-). Tyrosine 192 was the predominant site of both nitration and chlorination by MPO and was also the major site of nitration by ONOO -. Electron paramagnetic spin resonance studies of spin-labeled apoA-I revealed that residue 192 was located in an unusually hydrophilic environment. Moreover, the environment of residue 192 became much more hydrophobic when apoA-I was incorporated into discoidal HDL, and Tyr 192 of HDL-associated apoA-I was a poor substrate for nitration by both myeloperoxidase and ONOO-, suggesting that solvent accessibility accounted in part for the reactivity of Tyr192. The ability of lipid-free apoA-I to facilitate ATP-binding cassette transporter A1 cholesterol transport was greatly reduced after chlorination by MPO. Loss of activity occurred in concert with chlorination of Tyr192. Both ONOO - and MPO nitrated Tyr192 in high yield, but unlike chlorination, nitration minimally affected the ability of apoA-I to promote cholesterol efflux from cells. Our results indicate that Tyr192 is the predominant site of nitration and chlorination when MPO or ONOO- oxidizes lipid-free apoA-I but that only chlorination markedly reduces the cholesterol efflux activity of apoA-I. This impaired biological activity of chlorinated apoA-I suggests that MPO-mediated oxidation of HDL might contribute to the link between inflammation and cardiovascular disease.
UR - http://www.scopus.com/inward/record.url?scp=14044250955&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=14044250955&partnerID=8YFLogxK
U2 - 10.1074/jbc.M411484200
DO - 10.1074/jbc.M411484200
M3 - Article
C2 - 15574409
AN - SCOPUS:14044250955
VL - 280
SP - 5983
EP - 5993
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 7
ER -