In vitro analysis of the dominant negative effect of p53 mutants.

Missense mutations of the p53 tumour suppressor gene induce the formation of proteins with an altered affinity for DNA. These mutant proteins have either a wild-type or a mutant conformation. It has been established that, on association with wild-type protein, molecules with mutant conformation can drive the wild-type p53 into a mutant conformation. It is shown here that mutant proteins with a wild-type conformation can also inactivate wild-type p53 upon oligomerisation. The dominant negative activity of these mutants depends on their ability to bind to DNA. The less a mutant protein binds to DNA, the more it is dominant negative. Their dominant negative activity is also dependent on the DNA-binding site. The binding of wild-type to a low-affinity DNA element is more easily inactivated by a dominant negative mutant than its binding to a high-affinity DNA-binding site.