Influence of the N-terminal region on the oligomerisation between human and Xenopus laevis p53

The p53 proteins from human, murine and Xenopus laevis are tetrameric. Previous work has shown that both human and murine p53 can form heterotetramers. However, despite a very high level of sequence homology at their tetramerisation domain, the human and the X. laevis p53 do not form heterooligomers. It is shown here that when inserted in the human p53 protein, the X. laevis tetramerisation domain is able to oligomerise with the human one. This indicates that the inability of X. laevis p53 to heterooligomerise with human p53 is due to another structural difference. The use of N and C-truncated X. laevis p53 proteins reveals that the deletion of the N terminus favours from the heterooligomerisation between the human and the X. laevis p53. The oligomerisation of the X. laevis p53 with the human protein is also enhanced when the N terminus of the X. laevis p53 is replaced by the human one. Altogether these data suggest that the N terminus of p53 influences the oligomerisation. (C) 1999 Academic Press.