Identification of oligomerizing peptides.
The AraC DNA binding domain is inactive in a monomeric form but can activate transcription from the arabinose operon promoters upon its dimerization. We used this property to identify plasmids encoding peptide additions to the AraC DNA binding domain that could dimerize the domain. We generated a high diversity library of plasmids by inserting 90-base oligonucleotides of random sequence ahead of DNA coding for the AraC DNA binding domain in an expression vector, transforming, and selecting colonies containing functional oligomeric peptide-AraC DNA binding domain chimeric proteins by their growth on minimal arabinose medium. Six of seven Ara(+) candidates were partially characterized, and one was purified. Equilibrium analytical centrifugation experiments showed that it dimerizes with a dissociation constant of approximately 2 micrometer.
Biology Department, Johns Hopkins University, Baltimore, Maryland 21218, USA.
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D000595:Amino Acid Sequence; D051777:AraC Transcription Factor; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins / Q000737:chemistry*; D019281:Dimerization; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000302:isolation & purification; D012097:Repressor Proteins / Q000737:chemistry*; D014157:Transcription Factors
D051777:AraC Transcription Factor; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D010455:Peptides; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors