title: Selection of peptides that functionally replace a zinc finger in the Sp1 transcription factor by using a yeast combinatorial library.
abstract: We have developed a strategy for the identification of peptides able to functionally replace a zinc finger domain in a transcription factor. This strategy could have important ramifications for basic research on gene regulation and for the development of therapeutic agents. In this study in yeast, we expressed chimeric proteins that included a random peptide combinatorial library in association with two zinc finger domains and a transactivating domain. The library was screened for chimeric proteins capable of activating transcription from a target sequence in the upstream regulatory regions of selectable or reporter genes. In a screen of approximately 1.5 x 10(7) transformants we identified 30 chimeric proteins that exhibited transcriptional activation, some of which were able to discriminate between wild-type and mutant DNA targets. Chimeric library proteins expressed as glutathione S-transferase fusions bound to double-stranded oligonucleotides containing the target sequence, suggesting that the chimeras bind directly to DNA. Surprisingly, none of the peptides identified resembled a zinc finger or other well-known transcription factor DNA binding domain.
authors.affiliation: Department of Pharmacology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: X
authors.initials: X
authors.lastname: Cheng
authors.forename: J L
authors.initials: JL
authors.lastname: Boyer
authors.forename: R L
authors.initials: RL
authors.lastname: Juliano
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D019151:Peptide Library; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016335:Zinc Fingers / Q000235:genetics*
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D019151:Peptide Library; D011993:Recombinant Fusion Proteins; D016329:Sp1 Transcription Factor