A 'Spindle and Thread'-Mechanism Unblocks p53 Translation by Modulating N-Terminal Disorder

Abstract

Disordered proteins pose a major challenge to structural biology. A prominent example is the tumour suppressor p53, whose low expression levels and poor conformational stability due to a high degree of disorder hamper the development of cancer therapeutics. Here, we probe the role of N-terminal disorder in p53 by fusing the protein to an engineered spider silk domain termed NT*. The chimeric protein displays highly efficient translation and is fully active in human cancer cells. Electron microscopy and mass spectrometry reveal that the protein adopts a compact conformation. Molecular dynamics simulations and NMR measurements show that the disordered transactivation domain of p53 is wrapped around the NT* domain, resulting in a pseudo-globular structure. We find that expression of partially disordered cancer targets is similarly enhanced by fusion to NT*. In summary, we demonstrate that inducing co-translational folding via a molecular “spindle and thread” mechanism unblocks protein translation in vitro.