title: p53 contains large unstructured regions in its native state.
abstract: The human tumor suppressor protein p53 is understood only to some extent on a structural level. We performed a comprehensive biochemical and biophysical structure-function analysis of p53 full-length protein and p53 fragments. The analysis showed that p53 and the fragments investigated form stable functional units. Full-length p53 and the tetrameric fragment N93p53 (residues 93-393) are, however, destabilized significantly compared to the monomeric core domain (residues 94-312) and the monomeric fragment p53C312 (residues 1-312). At the physiological temperature of 37 degrees C and in the absence of modifications or stabilizing partners, wild-type p53 is more than 50% unfolded correlating with a 75% loss in DNA-binding activity. Furthermore the analysis of CD spectra revealed that full-length p53 contains large unstructured regions in its N and C-terminal parts. Our results indicate that full-length p53 is a modular protein consisting of defined structured and unstructured regions. We propose that p53 belongs to the growing family of loosely folded or partially unstructured native proteins. The lack of a rigid structure combined with the low overall stability may allow the physiological interaction of p53 with a multitude of partner proteins and the regulation of its turnover.
mesh_terms: D002151:Calorimetry; D002942:Circular Dichroism; D006801:Humans; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D021241:Spectrometry, Mass, Electrospray Ionization; D013329:Structure-Activity Relationship; D013696:Temperature; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D016159:Tumor Suppressor Protein p53