Protein Modification by Endogenously Generated Lipid Electrophiles: Mitochondria as the Source and Target

Determining
the impact of lipid electrophile-mediated protein damage
that occurs during oxidative stress requires a comprehensive analysis
of electrophile targets adducted under pathophysiological conditions.
Incorporation of ω-alkynyl linoleic acid into the phospholipids
of macrophages prior to activation by Kdo2-lipid A, followed
by protein extraction, click chemistry, and streptavidin affinity
capture, enabled a systems-level survey of proteins adducted by lipid
electrophiles generated endogenously during the inflammatory response.
Results revealed a dramatic enrichment for membrane and mitochondrial
proteins as targets for adduction. A marked decrease in adduction
in the presence of MitoTEMPO demonstrated a primary role for mitochondrial
superoxide in electrophile generation and indicated an important role
for mitochondria as both a source and target of lipid electrophiles,
a finding that has not been revealed by prior studies using exogenously
provided electrophiles.