Cobra Cardiotoxin from Naja mossambica mossambica Promotes Neurodegeneration by Targeting Mitochondria

Abstract

Cobra cardiotoxin (CTX) is a basic, cationic protein with a highly conserved structure that has been shown to colocalize to mitochondria in cells and induce mitochondrial dysfunction. Since CTX is a positively charged protein, I hypothesize that basic residues in CTX from Naja mossambica mossambica will interact with negatively charged phospholipids in the mitochondrial membrane, specifically cardiolipin. CTX from Naja naja mossambica (N. n. mossambica) was diluted and tested on fetal C57BL/6J mouse cortical neurons and SH-SY5Y neuroblastoma. The lethal dose 50 (LD50) for each cell line was examined using the lactate dehydrogenase (LDH) release assay. Confocal microscopy confirmed cellular uptake of rhodamine-labeled CTX and colocalization to mitochondria and, molecular dynamics showed cardiolipin as a target in a model membrane made of phosphatidylcholine and CDL. Lastly, CTX induced significant decrease in total ATP production, mitochondrial-derived ATP, basal and maximal oxygen consumption rates in SH-SY5Y neuroblastoma.