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∗). The chimeric protein displays highly efficient translation and is fully active in human cancer cells. Biophysical characterization reveals a compact conformation, with the disordered transactivation domain of p53 wrapped around the NT∗ domain. We conclude that interactions with NT∗ help to unblock translation of the proline-rich disordered region of p53. Expression of partially disordered cancer targets is similarly enhanced by NT∗. In summary, we demonstrate that inducing co-translational folding via a molecular "spindle and thread" mechanism unblocks protein translation in vitro.

Department of Biochemistry and Biophysics Stockholm University 10691 Stockholm Sweden

Department of Biomedical Engineering and Health Systems School of Engineering Sciences in Chemistry Biotechnology and Health KTH Royal Institute of Technology 141 83 Huddinge Sweden

Department of Biomedical Engineering and Health Systems School of Engineering Sciences in Chemistry Biotechnology and Health KTH Royal Institute of Technology 141 83 Huddinge Sweden; Department of Biosciences and Nutrition Karolinska Institutet 148 13 Huddinge Sweden

Department of Biosciences and Nutrition Karolinska Institutet 148 13 Huddinge Sweden

Department of Biosciences and Nutrition Karolinska Institutet 148 13 Huddinge Sweden; Department of Anatomy Physiology and Biochemistry Swedish University of Agricultural Sciences Box 7011 Uppsala 750 07 Sweden

Department of Materials and Environmental Chemistry Stockholm University 10691 Stockholm Sweden

Department of Microbiology Tumor and Cell Biology Karolinska Institutet Biomedicum Solnavägen 9 17165 Solna Sweden

Department of Microbiology Tumor and Cell Biology Karolinska Institutet Biomedicum Solnavägen 9 17165 Solna Sweden; School of Natural Sciences and Health Tallinn University Narva mnt 25 10120 Tallinn Estonia

Disease Intervention Technology Laboratory Institute of Molecular and Cell Biology A STAR 8A Biomedical Grove 06 06 Immunos Singapore 138648 Singapore

Division of Physiological Chemistry 1 Department of Medical Biochemistry and 5 Biophysics Karolinska Institutet Biomedicum Solnavägen 9 17165 Solna Sweden

Division of Physiological Chemistry 1 Department of Medical Biochemistry and 5 Biophysics Karolinska Institutet Biomedicum Solnavägen 9 17165 Solna Sweden; Department of Pharmacological and Technological Chemistry 1 M Sechenov 1st Moscow State Medical University Moscow 119146 Russia; The National Medical Research Center for Endocrinology 115478 Moscow Russia

Masaryk Memorial Cancer Institute RECAMO Zluty kopec 7 656 53 Brno Czech Republic

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