title: Inhibition of an activated Ras protein with genetically selected peptide aptamers.
abstract: Mutant alleles of Ras maintain an activated, GTP-bound conformation and relay mitogenic signals that cannot be turned off. A genetic selection in Saccharomyces cerevisiae was used to identify peptide aptamers that suppress the growth arrest phenotype of an activated Ras allele. Peptide aptamers were expressed as C-terminal fusions to glutathione-S-transferase. Modifications that alter the coding capacity of the peptide aptamer indicate it is necessary for Ras2-Val19 suppression. Aptamer expression also reduces the elevated levels of cAMP and suppresses the heat shock sensitivity characteristic of Ras-activated yeast cells. The peptide aptamer retains suppressor activity when fused to thioredoxin. The peptide aptamer expression strategy described here indicates that aptamers presented as unconstrained peptides have functional capacity in vivo.
authors.affiliation: Department of Immunology, Veterans Affairs Medical Center, Portland, Oregon 97201, USA. skurtz@qwest.net
authors.forename: Stephen E
authors.initials: SE
authors.lastname: Kurtz
authors.forename: Kim
authors.initials: K
authors.lastname: Esposito
authors.forename: Weimin
authors.initials: W
authors.lastname: Tang
authors.forename: Rolf
authors.initials: R
authors.lastname: Menzel
mesh_terms: D001665:Binding Sites / Q000235:genetics; D005656:Fungal Proteins; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D016153:Genes, Suppressor; D008024:Ligands; D019151:Peptide Library; D010455:Peptides / Q000235:genetics*; D015202:Protein Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D018631:ras Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D008024:Ligands; D019151:Peptide Library; D010455:Peptides; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C489015:RAS2 protein, S cerevisiae; D018631:ras Proteins