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Single molecule studies reveal that p53 tetramers dynamically bind response elements containing one or two half sites

Authors
  • Ly, Elina1
  • Kugel, Jennifer F.1
  • Goodrich, James A.1
  • 1 University of Colorado Boulder, 596 UCB, Boulder, CO, 80309, USA , Boulder (United States)
Type
Published Article
Journal
Scientific Reports
Publisher
Springer Nature
Publication Date
Sep 30, 2020
Volume
10
Issue
1
Identifiers
DOI: 10.1038/s41598-020-73234-6
Source
Springer Nature
License
Green

Abstract

The tumor suppressor protein p53 is critical for cell fate decisions, including apoptosis, senescence, and cell cycle arrest. p53 is a tetrameric transcription factor that binds DNA response elements to regulate transcription of target genes. p53 response elements consist of two decameric half-sites, and data suggest one p53 dimer in the tetramer binds to each half-site. Despite a broad literature describing p53 binding DNA, unanswered questions remain, due partly to the need for more quantitative and structural studies with full length protein. Here we describe a single molecule fluorescence system to visualize full length p53 tetramers binding DNA in real time. The data revealed a dynamic interaction in which tetrameric p53/DNA complexes assembled and disassembled without a dimer/DNA intermediate. On a wild type DNA containing two half sites, p53/DNA complexes existed in two kinetically distinct populations. p53 tetramers bound response elements containing only one half site to form a single population of complexes with reduced kinetic stability. Altering the spacing and helical phasing between two half sites affected both the population distribution of p53/DNA complexes and their kinetic stability. Our real time single molecule measurements of full length p53 tetramers binding DNA reveal the parameters that define the stability of p53/DNA complexes, and provide insight into the pathways by which those complexes assemble.

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