Pseudophosphorylation of single residues of the J‐domain of DNAJA2 regulates the holding/folding balance of the Hsc70 system

• Published in: Protein science Vol. 33; no. 8; pp. e5105 - n/a
• Main Authors: Velasco‐Carneros, Lorea, Bernardo‐Seisdedos, Ganeko, Maréchal, Jean‐Didier, Millet, Oscar, Moro, Fernando, Muga, Arturo
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.08.2024; Wiley Subscription Services, Inc
• Subjects: chaperone; DNAJA2; Folding; Homeostasis; Hsc70; HSC70 Heat-Shock Proteins - chemistry; HSC70 Heat-Shock Proteins - genetics; HSC70 Heat-Shock Proteins - metabolism; Hsc70 protein; HSP40 Heat-Shock Proteins - chemistry; HSP40 Heat-Shock Proteins - genetics; HSP40 Heat-Shock Proteins - metabolism; Hsp70 protein; Humans; J‐domain; Models, Molecular; Nucleotides; Phosphorylation; Protein Domains; Protein Folding; Proteins; Residues; protein folding; chaperone; J‐domain; Hsc70; phosphorylation; DNAJA2
• ISSN: 0961-8368; 1469-896X; 1469-896X
• DOI: 10.1002/pro.5105

The Hsp70 system is essential for maintaining protein homeostasis and comprises a central Hsp70 and two accessory proteins that belong to the J‐domain protein (JDP) and nucleotide exchange factor families. Posttranslational modifications offer a means to tune the activity of the system. We explore how phosphorylation of specific residues of the J‐domain of DNAJA2, a class A JDP, regulates Hsc70 activity using biochemical and structural approaches. Among these residues, we find that pseudophosphorylation of Y10 and S51 enhances the holding/folding balance of the Hsp70 system, reducing cochaperone collaboration with Hsc70 while maintaining the holding capacity. Truly phosphorylated J domains corroborate phosphomimetic variant effects. Notably, distinct mechanisms underlie functional impacts of these DNAJA2 variants. Pseudophosphorylation of Y10 induces partial disordering of the J domain, whereas the S51E substitution weakens essential DNAJA2‐Hsc70 interactions without a large structural reorganization of the protein. S51 phosphorylation might be class‐specific, as all cytosolic class A human JDPs harbor a phosphorylatable residue at this position.