Dynamics of the intrinsically disordered protein NUPR1 in isolation and in its fuzzy complexes with DNA and prothymosin alpha
Por:
Neira, J, Palomino-Schatzlein, M, Ricci, C, Ortore, M, Rizzuti, B and Iovanna, J
Publicada:
1 nov 2019
Resumen:
Intrinsically disordered proteins (IDPs) explore diverse conformations in their free states and, a few of them, also in their molecular complexes. This functional plasticity is essential for the function of IDPs, although their dynamics in both free and bound states is poorly understood. NUPR1 is a protumoral multifunctional IDP, activated during the acute phases of pancreatitis. It interacts with DNA and other IDPs, such as prothymosin alpha (ProT alpha), with dissociation constants of similar to 0.5 mu M, and a 1:1 stoichiometry. We studied the structure and pico-second-to-nanosecond (ps-ns) dynamics by using both NMR and SAXS in: (i) isolated NUPR1; (ii) the NUPR1/ProT alpha complex; and (iii) the NUPR1/double stranded (ds) GGGCGCGCCC complex. Our SAXS findings show that NUPR1 remained disordered when bound to either partner, adopting a worm-like conformation; the fuzziness of bound NUPR1 was also pinpointed by NMR. Residues with the largest values of the relaxation rates (R-1, R-1p, R-2 and eta(xy)), in the free and bound species, were mainly clustered around the 30s region of the sequence, which agree with one of the protein hot-spots already identified by site-directed mutagenesis. Not only residues in this region had larger relaxation rates, but they also moved slower than the rest of the molecule, as indicated by the reduced spectral density approach (RSDA). Upon binding, the energy landscape of NUPR1 was not funneled down to a specific, well-folded conformation, but rather its backbone flexibility was kept, with distinct motion occurring at the hot-spot region.
Green Published, Green Submitted
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