LDL phospholipid hydrolysis produces modified electronegative particles with an unfolded apoB-100 protein.
Electronegative low density lipoprotein (LDL(-)) formation that structurally resembles LDL(-) isolated from plasma was evaluated after LDL treatment with snake venom phospholipase A(2) (PLA(2)). PLA(2) treatment of LDL increased its electrophoretic mobility in proportion to the amount of LDL(-) formed without evidence of lipid peroxidation. These changes dose-dependently correlated with the degree of phospholipid hydrolysis. Strong immunoreactivity of LDL(-) subfraction from plasma and PLA(2)-treated LDL (PLA(2)-LDL) to amyloid oligomer-specific antibody was observed. Higher beta-strand structural content and unfolding proportionate to the loss of alpha-helical structure of apolipoprotein B-100 (apoB-100) of LDL(-) isolated from both native and PLA(2)-LDLs was demonstrated by circular dichroism (CD) spectropolarimetry. These structural changes resembled the characteristics of some oxidatively modified LDLs and soluble oligomeric aggregates of amyloidogenic proteins. PLA(2)-LDL was also more susceptible to nitration by peroxynitrite, likely because of exposure of otherwise inaccessible hydrophilic and hydrophobic domains arising from apoB-100 unfolding. This was also demonstrated for plasma LDL(-). In contrast, PLA(2)-LDL was more resistant to copper-mediated oxidation that was reversed upon the addition of small amounts of unsaturated fatty acids. The observed similarities between PLA(2)-LDL(-)-derived LDL(-) and plasma LDL(-) implicate a role for secretory PLA(2) in producing modified LDL(-) that is facilitated by unfolding of apoB-100.
Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles, CA 90033, USA. asatryan@usc.edu
Liana
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Asatryan
Ryan T
RT
Hamilton
J Mario
JM
Isas
Juliana
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Hwang
Rakez
R
Kayed
Alex
A
Sevanian
D053299:Apolipoprotein B-100; D001055:Apolipoproteins B / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D004546:Elapid Venoms; D004586:Electrophoresis; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000494:pharmacology; D010741:Phospholipases A / Q000494:pharmacology*; D010743:Phospholipids / Q000378:metabolism; D011487:Protein Conformation / Q000187:drug effects; D011489:Protein Denaturation / Q000187:drug effects; D055672:Static Electricity
D053299:Apolipoprotein B-100; D001055:Apolipoproteins B; D004546:Elapid Venoms; D005231:Fatty Acids, Unsaturated; D008077:Lipoproteins, LDL; D010743:Phospholipids; D030421:Peroxynitrous Acid; D010741:Phospholipases A