TEMPERATURE SENSITIVITY FOR CONFORMATION IS AN INTRINSIC PROPERTY OF WILD-TYPE P53

The tumour-suppressor protein p53 is a metal-binding transcription fac tor with sequence-specific DNA-binding capacity. In cancer, mutation o f p53 disrupts protein conformation with consequent loss of DNA bindin g and associated tumour-suppressor function. In vitro, the conformatio n and DNA-binding activity of wild-type p53 are subject to redox modul ation and are abrogated by exposure to metal chelators. In the present study, we have used the chelator 1,10-phenanthroline (OF) to probe th e effect of temperature on the conformational stability of p53 transla ted in vitro. Whereas low temperature (30 degrees C) stabilised wild-t ype p53 conformation and protected against chelation, high temperature (41 degrees C) promoted destabilisation and enhanced chelation, indic ating that temperature influences the folding of wild-type p53. Destab ilisation of p53 tertiary structure induced protein aggregation throug h hydrophobic interactions, consistent with the notion that wild-type p53 contains a hydrophobic core which may become exposed by metal chel ation. These results indicate that temperature sensitivity for conform ation is an intrinsic property of wild-type p53 and suggests that smal l changes in temperature may directly affect p53 function.