Assignment of the disordered, proline-rich N-terminal domain of the tumour suppressor p53 protein using (1)H(N) and (1)H(α)-detected NMR measurements

Protein p53 is mostly known for playing a key role in tumour suppression, and mutations in the p53 gene are amongst the most frequent genomic events accompanying oncogenic transformation. Continuous research is conducted to target disordered proteins/protein regions for cancer therapy, for which atomic level information is also necessary. The disordered N-terminal part of p53 contains the transactivation and the proline-rich domains—which besides being abundant in proline residues—contains repetitive Pro-Ala motifs. NMR assignment of such repetitive, proline-rich regions is challenging due to the lack of amide protons in the (1)H(N)-detected approaches, as well as due to the small chemical shift dispersion. In the present study we perform the full assignment of the p53(1–100) region by applying a combination of (1)H(N)- and (1)H(α)-detected NMR experiments. We also show the increased information content when using real-time homo- and heteronuclear decoupled acquisition schemes. On the other hand, we highlight the presence of minor proline species, and using Pro-selective experiments we determine the corresponding cis or trans conformation. Secondary chemical shifts for (C(α)–C(β)) atoms indicate the disordered nature of this region, with expected helical tendency for the TAD1 region. As the role of the proline-rich domain is yet not well understood our results can contribute to further successful investigations.