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Protein disorder is a major hurdle for 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 pose major challenges to the development of cancer therapeutics. Here, we address these issues by fusing p53 to an engineered spider silk domain termed NT*. The chimeric protein displays highly efficient translation in vitro and in E. coli and is fully active in human cancer cells. The transmission electron microscopy structure and native mass spectrometry reveal that the full-length p53 fusion protein adopts a compact conformation. Molecular dynamics simulations show that the disordered transactivation domain of p53 is wound around the NT* domain via a series of folding events, resulting in a globular structure. We find that expression of B-Raf, another partially disordered cancer target, is similarly enhanced by fusion to NT*. In summary, we demonstrate how inducing co-translational folding via a molecular “spindle and thread” mechanism can overcome poor translation efficiency of partially disordered proteins.

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.

Disordered proteins pose a major challenge to structural biology. A prominent example is the tumor suppressor p53, whose low expression levels and poor conformational stability hamper the development of cancer therapeutics. All these characteristics make it a prime example of "life on the edge of solubility." Here, we investigate whether these features can be modulated by fusing the protein to a highly soluble spider silk domain (NT