Phosphorylation orchestrates the structural ensemble of the intrinsically disordered protein HMGA1a and modulates its DNA binding to the NFκB promoter.

Abstract

High Mobility Group Protein A1a (HMGA1a) is a highly abundant nuclear protein, which plays a crucial role during embryogenesis, cell differentiation, and neoplasia. Here, we present the first ever NMR-based structural ensemble of full length HMGA1a. Our results show that the protein is not completely random coil but adopts a compact structure consisting of transient long-range contacts, which is regulated by post-translational phosphorylation. The CK2-, cdc2- and cdc2/CK2-phosphorylated forms of HMGA1a each exhibit a different binding affinity towards the PRD2 element of the NFκB promoter. Our study identifies connected regions between phosphorylation sites in the wildtype ensemble that change considerably upon phosphorylation, indicating that these posttranslational modifications sites are part of an electrostatic contact network that alters the structural ensemble by shifting the conformational equilibrium. Moreover, ITC data reveal that the CK2-phosphorylated HMGA1a exhibits a different DNA promoter binding affinity for the PRD2 element. Furthermore, we present the first structural model for AT-hook 1 of HMGA1a that can adopt a transient α-helical structure, which might serve as an additional regulatory mechanism in HMAG1a. Our findings will help to develop new therapeutic strategies against HMGA1a-associated cancers by taking posttranslational modifications into consideration.

• Authors: Bastian Kohl, Xueyin Zhong, Christian Herrmann, Raphael Stoll
• Journal: Nucleic acids research (Nucleic Acids Res) Vol. 47 Issue 22 Pg. 11906-11920 (12 16 2019) ISSN: 1362-4962 [Electronic] England
• PMID: 31340016 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author(s) 2019. Published by Oxford University Press on behalf of Nucleic Acids Research.

Chemical References

• Intrinsically Disordered Proteins
• NF-kappa B
• HMGA1a Protein
• DNA
• Casein Kinase II
• CDC2 Protein Kinase

Topics

• CDC2 Protein Kinase (metabolism)
• Casein Kinase II (metabolism)
• DNA (metabolism)
• HMGA1a Protein (chemistry, metabolism)
• Humans
• Intrinsically Disordered Proteins (chemistry, metabolism)
• Models, Molecular
• NF-kappa B (genetics, metabolism)
• Nuclear Magnetic Resonance, Biomolecular
• Phosphorylation
• Promoter Regions, Genetic
• Protein Binding
• Protein Folding
• Protein Interaction Domains and Motifs (genetics)
• Protein Processing, Post-Translational
• Protein Structure, Secondary