title: Membrane Remodeling by a Bacterial Phospholipid-Methylating Enzyme.
abstract: Membrane deformation by proteins is a universal phenomenon that has been studied extensively in eukaryotes but much less in prokaryotes. In this study, we discovered a membrane-deforming activity of the phospholipidN-methyltransferase PmtA from the plant-pathogenic bacteriumAgrobacterium tumefaciensPmtA catalyzes the successive three-stepN-methylation of phosphatidylethanolamine to phosphatidylcholine. Here, we defined the lipid and protein requirements for the membrane-remodeling activity of PmtA by a combination of transmission electron microscopy and liposome interaction studies. Dependent on the lipid composition, PmtA changes the shape of spherical liposomes either into filaments or small vesicles. Upon overproduction of PmtA inA. tumefaciens, vesicle-like structures occur in the cytoplasm, dependent on the presence of the anionic lipid cardiolipin. The N-terminal lipid-binding α-helix (αA) is involved in membrane deformation by PmtA. Two functionally distinct and spatially separated regions in αA can be distinguished. Anionic interactions by positively charged amino acids on one face of the helix are responsible for membrane recruitment of the enzyme. The opposite hydrophobic face of the helix is required for membrane remodeling, presumably by shallow insertion into the lipid bilayer.IMPORTANCEThe ability to alter the morphology of biological membranes is known for a small number of some bacterial proteins. Our study adds the phospholipidN-methyltransferase PmtA as a new member to the category of bacterial membrane-remodeling proteins. A combination ofin vivoandin vitromethods reveals the molecular requirements for membrane deformation at the protein and phospholipid level. The dual functionality of PmtA suggests a contribution of membrane biosynthesis enzymes to the complex morphology of bacterial membranes.
authors.affiliation: Microbial Biology, Faculty of Biology, Ruhr University Bochum, Bochum, Germany.
authors.forename: Linna
authors.initials: L
authors.lastname: Danne
authors.affiliation: Microbial Biology, Faculty of Biology, Ruhr University Bochum, Bochum, Germany.
authors.forename: Meriyem
authors.initials: M
authors.lastname: Aktas
authors.affiliation: Department of Cardiovascular Physiology, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Unger
authors.affiliation: Department of Cardiovascular Physiology, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany.
authors.forename: Wolfgang A
authors.initials: WA
authors.lastname: Linke
authors.affiliation: Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Erdmann
authors.affiliation: Microbial Biology, Faculty of Biology, Ruhr University Bochum, Bochum, Germany franz.narberhaus@rub.de.
authors.forename: Franz
authors.initials: F
authors.lastname: Narberhaus
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D008081:Liposomes / Q000378:metabolism; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D008081:Liposomes; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010743:Phospholipids; C483858:phosphatidylethanolamine; D008780:Methyltransferases; C435200:PmtA protein, bacteria