Understanding the role of B-insert in Dynamin related protein1 (Drp1) - cardiolipin interactions

Abstract

Mitochondria exhibits dynamic morphology which is maintained by constant cycle’s dynamic fission and fusion. Dynamin related protein 1 (Drp1), a large multidomain GTPase, is a crucial player involved in mitochondrial fission. Cardiolipin is the signature mitochondrial lipid and is implicated in regulating various mitochondrial function. Cardiolipin-Drp1 interactions are necessary for promoting its self-assembly and influences stimulated GTPase activity of Drp1. B-insert region in Drp1 is speculated to be the cardiolipin binding domain. Drp1 B-insert deletion mutant fails to localise to mitochondria, indicating the importance of B-insert for membrane binding in Drp1. In this study, we investigate B-insert lipid binding specificity to understand role of B-insert in Drp1 recruitment to the membranes. We show that B-insert displays preferential specificity in binding to cardiolipin and propose that B-insert is required for Drp1-cardiolipin interactions. B-insert shows better specificity to cardiolipin than Nonyl-Acridine Orange(NAO) described in literature to be a cardiolipin specific probe. We also considered the possibility of using B-insert as a probe for cardiolipin and expressed it in-vivo to observe membrane localisation.