Enhanced Tubulation of Liposome Containing Cardiolipin by MamY Protein from Magnetotactic Bacteria

Lipid tubulesare of particular interest for many potential applicationsin nanotechnology. Among various lipid tubulefabrication techniques, the morphological regulation of membrane structureby proteins mimicking biological processes may provide the chances to form lipidtubes with highly tuned structures. Magnetotactic bacteriasynthesize magnetosomes(a unique prokaryoticorganelle comprising a magnetite crystal within a lipidenvelope). MamY protein is previously identified as the magnetosomeprotein responsible for magnetosomevesicle formation and stabilization. Furthermore, MamY is shown in vitro liposome tubulationactivity. In this study, the interaction of MamY and phospholipids is investigated by using a lipids-immobilized membrane strip and a peptide array. Here, the binding of MamY to the anionic phospholipid, cardiolipin, is found and enhanced liposome tubulationefficiency. The authors propose the interaction is responsible for recruiting and locating cardiolipinto elongate liposome in vitro. The authors also suggest a similar mechanism for the invaginationsite in magnetosomesvesicle formation, where the lipiditself contributes further to increasing the curvature. These findings are highly important to develop an effective biomimetic synthesistechnique of lipid tubulesand to elucidate the unique prokaryoticorganelle formation in magnetotactic bacteria.