title: The N terminus of p53 regulates its dissociation from DNA.
abstract: It is important to gain insight into p53 DNA binding and how it is regulated. By using electrophoretic mobility shift assays and DNase I footprinting, we show that a region within the N terminus of the protein controls the dissociation of p53 from a p53-binding site. When p53 is bound by a number of N-terminal-specific monoclonal antibodies, its rate of dissociation from DNA is reduced, and its ability to protect a cognate site from DNase I digestion is increased. Moreover, greatly reduced dissociation is observed with p53 protein lacking the N-terminal 96 amino acids. By contrast, deletion of the C terminus does not affect p53 dissociation from DNA or DNase I protection. p53 protein expressed in and purified from bacterial cells displays markedly more instability on its consensus DNA-binding site than does p53 produced in insect cells, suggesting that post-translational modifications may affect the stability of the protein. Our results provide evidence that the N terminus of p53 possesses an auto-inhibitory function that is mechanistically different from the inhibitory region at the C terminus.
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
authors.forename: C
authors.initials: C
authors.lastname: Cain
authors.forename: S
authors.initials: S
authors.lastname: Miller
authors.forename: J
authors.initials: J
authors.lastname: Ahn
authors.forename: C
authors.initials: C
authors.lastname: Prives
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D011485:Protein Binding; D017384:Sequence Deletion; D018411:Spodoptera; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000378:metabolism*
chemical_list: D016159:Tumor Suppressor Protein p53; D004247:DNA; D003850:Deoxyribonuclease I