Cell Cycle Epub ahead of print (2010)

Despite having a small genome and only four cell types, the simple creature Trichoplax adhaerens holds clues about the evolutionary origin of p53, the most commonly mutated human tumour-suppressor gene.

David Lane and his colleagues at Singapore's Agency for Science, Technology and Research found sequences in the Trichoplax genome that are similar to those of human p53 and Mdm2. The latter tightly regulates p53 in humans and other vertebrates.

Key binding sites between the p53 and Mdm2 proteins in this amoeba-like creature (Mdm2 protein pictured, above left, in cyan, p53 fragment in orange) also seem to be conserved in humans (right). The authors suggest that these two proteins and their interaction have existed for more than a billion years and emerged much earlier in evolutionary history than previously thought.