Cardiolipin is an Optimal Phospholipid for the Assembly, Stability, and Proper Functionality of the Dimeric Form of NhaA Na+/H+ Antiporter

Abstract

AbstractCardiolipin (CL) was shown to bound to the dimer interface of NhaA Na+/H+antiporter. Here, we explore the cardiolipin-NhaA interaction bothin vitroandin vivo. Using a novel and straightforwardin-vitroassay in which n-dodecyl β-D maltoside (DDM) detergent is used to delipidate the dimer interface and to split the dimers into monomers; the monomers are subsequently exposed to cardiolipin or the otherE. coliphospholipids. Most efficient reconstitution of dimers is observed by cardiolipin. This assay is likely to be applicable to future studies of protein–lipid interactions.In-vivoexperiments further reveal that cardiolipin is necessary for NhaA survival. Although less efficient phosphatidyl-glycerol (PG) can also reconstitute NhaA monomers to dimers. We also identify a putative cardiolipin binding site. Our observations may contribute to drug design, as human NhaA homologues, which are involved in severe pathologies, might also require specific phospholipids.