High affinity insertion/deletion lesion binding by p53. Evidence for a role of the p53 central domain.

Szak ST, Pietenpol JA
J Biol Chem. 1999 274 (6): 3904-9

PMID: 9920946 · DOI:10.1074/jbc.274.6.3904

In addition to binding DNA in a sequence-specific manner, p53 can interact with nucleic acids in a sequence-independent manner. p53 can bind short single-stranded DNA and double-stranded DNA containing nucleotide loops; these diverse associations may be critical for p53 signal transduction. In this study, we analyzed p53 binding to DNA fragments containing insertion/deletion mismatches (IDLs). p53 required an intact central domain and dimerization domain for high affinity complex formation with IDLs. In fact, the C terminus of p53 (amino acids 293-393) was functionally replaceable with a foreign dimerization domain in IDL binding assays. From saturation binding studies we determined that the KD of p53 binding to IDLs was 45 pM as compared with a KD of 31 pM for p53 binding to DNA fragments containing a consensus binding site. Consistent with these dissociation constants, p53-IDL complexes were dissociated with relatively low concentrations of competitor consensus site-containing DNA. Although p53 has a higher affinity for DNA with a consensus site as compared with IDLs, the relative number and availability of each form of DNA in a cell immediately after DNA damage may promote p53 interaction with DNA lesions. Understanding how the sequence-specific and nonspecific DNA binding activities of p53 are integrated will contribute to our knowledge of how signaling cascades are initiated after DNA damage.

MeSH Terms (12)

Animals Base Sequence Binding, Competitive Cell Line Complement C3 DNA DNA-Binding Proteins DNA Damage Protein Binding Recombinant Proteins Spodoptera Tumor Suppressor Protein p53

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