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. Prev ious work has shown that both human and murine p53 can form heterotetramers . However, despite a very high level of sequence homology at their tetramer isation 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. laev is tetramerisation domain is able to oligomerise with the human one. This i ndicates that the inability of X. laevis p53 to heterooligomerise with huma n 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. Th e oligomerisation of the X. laevis p53 with the human protein is also enhan ced 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 oli gomerisation. (C) 1999 Academic Press.