title: Isolation of peptide aptamers that inhibit intracellular processes.
abstract: We have developed a method for isolation of random peptides that inhibit intracellular processes in bacteria. A library of random peptides expressed as fusions to Escherichia coli thioredoxin (aptamers) were expressed under the tight control of the arabinose-inducible P(BAD) promoter. A selection was applied to the library to isolate aptamers that interfered with the activity of thymidylate synthase (ThyA) in vivo. Expression of an aptamer isolated by this method resulted in a ThyA(-) phenotype that was suppressed by simultaneous overexpression of ThyA. Two-hybrid analysis showed that this aptamer is likely to interact with ThyA in vivo. The library also was screened for aptamers that inhibited growth of bacteria expressing them, and five such aptamers were characterized. Four aptamers were bacteriostatic when expressed, whereas one showed a bactericidal effect. Introduction of translational stop codons into various aptamers blocked their activity, suggesting that their biological effects were likely to be due to protein aptamer rather than RNA. Combinatorial aptamers provide a new genetic and biochemical tool for identifying targets for antibacterial drug development.
authors.affiliation: Department of Microbiology, Shipley Institute of Medicine, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Blum
authors.forename: S L
authors.initials: SL
authors.lastname: Dove
authors.forename: A
authors.initials: A
authors.lastname: Hochschild
authors.forename: J J
authors.initials: JJ
authors.lastname: Mekalanos
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003001:Cloning, Molecular; D015195:Drug Design; D004926:Escherichia coli / Q000254:growth & development; D015870:Gene Expression; D008969:Molecular Sequence Data; D010452:Peptide Biosynthesis; D010443:Peptide Chain Termination, Translational; D010455:Peptides / Q000302:isolation & purification* / Q000494:pharmacology; D013879:Thioredoxins / Q000235:genetics; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D010455:Peptides; D013879:Thioredoxins; D013940:Thymidylate Synthase