title: Acetylation of lysine 120 of p53 endows DNA-binding specificity at effective physiological salt concentration.
abstract: Lys120 in the DNA-binding domain (DBD) of p53 becomes acetylated in response to DNA damage. But, the role and effects of acetylation are obscure. We prepared p53 specifically acetylated at Lys120, AcK120p53, by in vivo incorporation of acetylated lysine to study biophysical and structural consequences of acetylation that may shed light on its biological role. Acetylation had no affect on the overall crystal structure of the DBD at 1.9-Å resolution, but significantly altered the effects of salt concentration on specificity of DNA binding. p53 binds DNA randomly in vitro at effective physiological salt concentration and does not bind specifically to DNA or distinguish among its different response elements until higher salt concentrations. But, on acetylation, AcK120p53 exhibited specific DNA binding and discriminated among response elements at effective physiological salt concentration. AcK120p53 and p53 had the highest affinity to the same DNA sequence, although acetylation reduced the importance of the consensus C and G at positions 4 and 7, respectively. Mass spectrometry of p53 and AcK120p53 DBDs bound to DNA showed they preferentially segregated into complexes that were either DNA(p53DBD)(4) or DNA(AcK120DBD)(4), indicating that the different DBDs prefer different quaternary structures. These results are consistent with electron microscopy observations that p53 binds to nonspecific DNA in different, relaxed, quaternary states from those bound to specific sequences. Evidence is accumulating that p53 can be sequestered by random DNA, and target search requires acetylation of Lys120 and/or interaction with other factors to impose specificity of binding via modulating changes in quaternary structure.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, United Kingdom.
authors.forename: Eyal
authors.initials: E
authors.lastname: Arbely
authors.forename: Eviatar
authors.initials: E
authors.lastname: Natan
authors.forename: Tobias
authors.initials: T
authors.lastname: Brandt
authors.forename: Mark D
authors.initials: MD
authors.lastname: Allen
authors.forename: Dmitry B
authors.initials: DB
authors.lastname: Veprintsev
authors.forename: Carol V
authors.initials: CV
authors.lastname: Robinson
authors.forename: Jason W
authors.initials: JW
authors.lastname: Chin
authors.forename: Andreas C
authors.initials: AC
authors.lastname: Joerger
authors.forename: Alan R
authors.initials: AR
authors.lastname: Fersht
mesh_terms: D000107:Acetylation; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage; D004926:Escherichia coli; D008239:Lysine / Q000737:chemistry; D008250:Lysine-tRNA Ligase / Q000378:metabolism; D017021:Methanosarcina barkeri / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D015202:Protein Engineering; D017434:Protein Structure, Tertiary; D012492:Salts / Q000737:chemistry; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry*
chemical_list: D012492:Salts; D016159:Tumor Suppressor Protein p53; D004247:DNA; D008250:Lysine-tRNA Ligase; D008239:Lysine