title: A transmembrane segment mimic derived from Escherichia coli diacylglycerol kinase inhibits protein activity.
abstract: The function of membrane proteins is inextricably linked to the proper packing and assembly of their independently helical transmembrane (TM) segments. Here we examined whether an externally added TM peptide analogue could specifically inhibit the function of the membrane protein from which it is derived by competing for native TM helix packing sites, thereby producing a non-functional peptide-protein complex. This hypothesis was tested using Lys-tagged peptides synthesized with sequences corresponding to the three TM segments of the homotrimeric Escherichia coli diacylglycerol kinase (DGK). The peptide corresponding to wild-type DGK TM-2 inhibited the protein's enzymatic activity in a dose-dependent manner through formation of an inactive pseudo-complex, whereas peptides derived from TM-1 and TM-3 were benign toward DGK structure/function. Also, substitution of a conserved residue (Glu-69) within the TM-2 peptide abolished these effects, demonstrating the strict sequence requirements for TM-2-mediated association. This strategy, coupled with the practical advantages of the water solubility of Lys-tagged TM peptides, may constitute an attractive approach for the design of therapeutic membrane protein modulators even in the absence of a high resolution structure.
authors.affiliation: Division of Structural Biology and Biochemistry, Research Institute, Hospital for Sick Children, 555 university Avenue, Toronto, Ontario M5G 1X8, Canada.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Partridge
authors.forename: Roman A
authors.initials: RA
authors.lastname: Melnyk
authors.forename: Dawn
authors.initials: D
authors.lastname: Yang
authors.forename: James U
authors.initials: JU
authors.lastname: Bowie
authors.forename: Charles M
authors.initials: CM
authors.lastname: Deber
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000378:metabolism*; D002942:Circular Dichroism; D003902:Detergents / Q000494:pharmacology; D019852:Diacylglycerol Kinase / Q000737:chemistry*; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism; D007700:Kinetics; D008823:Micelles; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013997:Time Factors
chemical_list: D003902:Detergents; D008823:Micelles; D010455:Peptides; D012967:Sodium Dodecyl Sulfate; D019852:Diacylglycerol Kinase