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Updated: Nov 18, 2025

Purification of Ubiquitinated p53 Proteins from Mammalian Cells
Published on: March 21, 2022
Phosphorylation-regulated HMGA1a-P53 interaction unveils the function of HMGA1a acidic tail phosphorylations via
Tongyao Wei1, Heng Liu1, Bizhu Chu2
1Department of Chemistry, State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Hong Kong, P. R. China.
Abstract:
As a typical member of intrinsically disordered proteins (IDPs), HMGA1a carries many post-translational modifications (PTMs). To study the undefined function of acidic tail phosphorylations, seven HMGA1a proteins with site-specific modification(s) were chemically synthesized via Ser/Thr ligation. We found that the phosphorylations significantly inhibit HMGA1a-P53 interaction and the phosphorylations can induce conformational change of HMGA1a from an "open state" to a "close state." Notably, the positively charged lysine-arginine (KR) clusters are responsible for modulating HMGA1a conformation via electrostatic interaction with the phosphorylated acidic tail. Finally, we used a synthetic protein-affinity purification mass spectrometry (SP-AP-MS) methodology to profile the specific interactors, which further supported the function of HMGA1a phosphorylation. Collectively, this study highlights a mechanism for regulating IDPs' conformation and function by phosphorylation of non-protein-binding domain and showcases that the protein chemical synthesis in combination with mass spectrometry can serve as an efficient tool to study the IDPs' PTMs.
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