MODULATION BY COPPER OF P53 CONFORMATION AND SEQUENCE-SPECIFIC DNA-BINDING - ROLE FOR CU(II) CU(I) REDOX MECHANISM

The tumor suppressor protein p53 is a metal-binding transcription fact or whose conformation and function are altered by mutation in cancers. Using murine p53 translated in vitro, we report here that concentrati ons of copper within the physiological range (< 30 mu M) alter the con formation of wild-type p53 and inhibit sequence-specific DNA-binding. Direct binding of copper to p53 in the form of Cu(I) was demonstrated by Electron Spin Resonance using a purified recombinant protein contai ning residues 1-343 of murine wild-type p53 fused to E. coli maltose b inding protein. Moreover, protection against the effect of Cu(II) sulf ate was achieved by the Cu(I)-specific chelator bathocuproinedisulfoni c acid but not by scavengers of reactive oxygen species, suggesting th at alteration of p53 by copper depends upon a Cu(II)/Cu(I) redox mecha nism, but does not require the production of reactive oxygen species. Thus copper at physiological concentrations can interact with wild-typ e p53 and affect its DNA-binding capacity.