title: Ceramide channel: Structural basis for selective membrane targeting.
abstract: A ceramide commonly found in mammalian cells, C16-ceramide (N-palmitoyl-d-erythro-sphingosine), is capable of forming large, protein-permeable channels in the mitochondrial outer membrane (MOM). However, C16-ceramide is unable to permeabilize the plasma membrane of erythrocytes. This specificity is unexpected considering that ceramide forms channels in simple phosphoglycerolipid membranes. Synthetic analogs of C16-ceramide with targeted changes at each of the functional regions of the molecule including methylation, altered hydrocarbon chain length, and changes in the stereochemistry, were tested to probe the role of ceramide's molecular features on its ability to form channels in these two different membrane types. The ability to permeabilize the MOM was relatively insensitive to modifications of the various functional groups of ceramide whereas the same modifications resulted in plasma membrane permeabilization (a gain of function rather than a loss of function). Some analogs (ceramine, NBD-labeled ceramide, C18,1 ceramide) gained another function, the ability to inhibit cytochrome oxidase. The gain of deleterious functions indicates that constraints on the structure of ceramide that is formed by the cell's synthetic machinery includes the avoidance of deleterious interactions. We propose that the specific structure of ceramide limits the size of its interactome (both proteins and lipids) thus reducing the likelihood of unwanted side effects.
authors.affiliation: Department of Biology, University of Maryland.
authors.forename: Meenu N
authors.initials: MN
authors.lastname: Perera
authors.affiliation: Department of Biology, University of Maryland.
authors.forename: Vidyaramanan
authors.initials: V
authors.lastname: Ganesan
authors.affiliation: Department of Pharmacology and Toxicology, University of Louisville.
authors.forename: Leah J
authors.initials: LJ
authors.lastname: Siskind
authors.affiliation: Department of Biochemistry & Molecular Biology, Medical University of South Carolina.
authors.forename: Zdzislaw M
authors.initials: ZM
authors.lastname: Szulc
authors.affiliation: Department of Biochemistry & Molecular Biology, Medical University of South Carolina.
authors.forename: Alicja
authors.initials: A
authors.lastname: Bielawska
authors.affiliation: Department of Chemistry and Biochemistry, City University of New York, Queens College.
authors.forename: Robert
authors.initials: R
authors.lastname: Bittman
authors.affiliation: Department of Biology, University of Maryland.
authors.forename: Marco
authors.initials: M
authors.lastname: Colombini
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002518:Ceramides / Q000737:chemistry* / Q000378:metabolism*; D004912:Erythrocytes / Q000166:cytology; D008930:Mitochondria, Liver / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002518:Ceramides; C097760:N-palmitoylsphingosine
keywords: Analog; Ceramide channel; Erythrocyte; Mitochondria; Sphingolipid;