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Identification of an allosteric binding site on the transcription factor p53 using a phage-displayed peptide library
M W Ravera1, J Cárcamo, R Brissette
1DGI BioTechnologies, Edison, New Jersey 08818, USA.
Abstract:
Monoclonal antibody PAb1620 recognizes a conformational epitope on the transcription factor p53 and, upon binding, allosterically inhibits p53 binding to DNA. A highly diverse (1.5 x 10(10) members) phage-displayed library of peptides containing 40 random amino acids was used to identify the PAb1620 binding site on p53. Panning this library against PAb1620 resulted in three unique peptides which have statistically significant sequence identities with p53 sufficient to identify the binding site as being composed of amino acids 106-113 and 146-156. Based on these results, we propose a mechanism by which PAb1620 can allosterically inhibit p53 binding to DNA through an indirect interaction between the antibody binding site and the L1 loop (amino acids 112-124) of p53, which is a component of the DNA binding region.
Insights
Monoclonal antibody PAb1620 inhibits the transcription factor p53
Area of Science:
- Molecular Biology
- Immunology
- Cancer Research
Background:
- The transcription factor p53 plays a critical role in cellular responses to stress.
- Monoclonal antibody PAb1620 targets a specific epitope on p53.
- Understanding antibody-protein interactions is key to developing targeted therapies.
Purpose of the Study:
- To identify the precise binding site of monoclonal antibody PAb1620 on the p53 protein.
- To elucidate the mechanism by which PAb1620 inhibits p53's DNA binding activity.
Main Methods:
- Utilized a large phage-displayed peptide library (1.5 x 10^10 members) for screening.
- Employed panning techniques to isolate peptides binding to PAb1620.
- Analyzed sequence identities between selected peptides and p53 to map the epitope.
Main Results:
- Identified three unique peptides with significant sequence homology to p53.
- Localized the PAb1620 binding site to amino acids 106-113 and 146-156 of p53.
- Proposed an allosteric inhibition mechanism involving indirect interaction with the p53 L1 loop.
Conclusions:
- Monoclonal antibody PAb1620 binds to a conformational epitope on p53, encompassing residues 106-113 and 146-156.
- PAb1620 allosterically inhibits p53 DNA binding through an indirect mechanism affecting the L1 loop.
- These findings provide insights into p53 regulation and potential therapeutic strategies.