title: Inhibition of membrane-associated methyltransferases by a cholesterol-based metal chelator.
abstract: We have designed, synthesized, and characterized a metal chelating compound that is based on the structure of cholesterol and contains the high affinity metal chelating group, lysine nitrilotriacetic acid (Lys-NTA). Using the enzyme isoprenylcysteine carboxylmethyltransferase (Icmt) from yeast as a model integral membrane metalloenzyme, we find that this agent potently inhibits Icmt activity with an IC(50) value between 35 and 75 microM, which is at least 40 times more potent than the best known Icmt metal chelating inhibitor, Zincon. We propose that the rigid hydrophobic cholesterol moiety promotes partitioning into the membrane, enabling the metal-binding NTA group(s) to inactivate the enzyme by metal chelation. Because this compound is based on a naturally occurring membrane lipid and appears to chelate metals buried deeply within water insoluble environments, this agent may also be useful as a general tool for identifying previously unappreciated metal dependencies of other classes of membrane proteins.
authors.affiliation: Department of Chemistry and Purdue Cancer Center, Purdue University, West Lafayette, Indiana 47907, USA.
authors.forename: Heather B
authors.initials: HB
authors.lastname: Hodges
authors.forename: Mingkang
authors.initials: M
authors.lastname: Zhou
authors.forename: Saubhik
authors.initials: S
authors.lastname: Haldar
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Anderson
authors.forename: David H
authors.initials: DH
authors.lastname: Thompson
authors.forename: Christine A
authors.initials: CA
authors.lastname: Hrycyna
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology*; D002614:Chelating Agents / Q000737:chemistry* / Q000494:pharmacology*; D002784:Cholesterol / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D008670:Metals / Q000737:chemistry*; D015394:Molecular Structure; D011496:Protein Methyltransferases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D002614:Chelating Agents; D004791:Enzyme Inhibitors; D008670:Metals; D029701:Saccharomyces cerevisiae Proteins; D002784:Cholesterol; D011496:Protein Methyltransferases; C498863:Ste14 protein, S cerevisiae