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Coto ALDS, Pereira AA, Oliveira SD, Moritz MNDO, Franco da Rocha AM, Dores-Silva PR, da Silva NSM, de Araújo Nogueira AR, Gava LM, Seraphim TV, Borges JC. Structural characterization of the human DjC20/HscB cochaperone in solution. Biochim Biophys Acta Proteins Proteom 2024; 1872:140970. [PMID: 37871810 DOI: 10.1016/j.bbapap.2023.140970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 09/27/2023] [Accepted: 10/14/2023] [Indexed: 10/25/2023]
Abstract
J-domain proteins (JDPs) form a very large molecular chaperone family involved in proteostasis processes, such as protein folding, trafficking through membranes and degradation/disaggregation. JDPs are Hsp70 co-chaperones capable of stimulating ATPase activity as well as selecting and presenting client proteins to Hsp70. In mitochondria, human DjC20/HscB (a type III JDP that possesses only the conserved J-domain in some region of the protein) is involved in [FeS] protein biogenesis and assists human mitochondrial Hsp70 (HSPA9). Human DjC20 possesses a zinc-finger domain in its N-terminus, which closely contacts the J-domain and appears to be essential for its function. Here, we investigated the hDjC20 structure in solution as well as the importance of Zn+2 for its stability. The recombinant hDjC20 was pure, folded and capable of stimulating HSPA9 ATPase activity. It behaved as a slightly elongated monomer, as attested by small-angle X-ray scattering and SEC-MALS. The presence of Zn2+ in the hDjC20 samples was verified, a stoichiometry of 1:1 was observed, and its removal by high concentrations of EDTA and DTPA was unfeasible. However, thermal and chemical denaturation in the presence of EDTA led to a reduction in protein stability, suggesting a synergistic action between the chelating agent and denaturators that facilitate protein unfolding depending on metal removal. These data suggest that the affinity of Zn+2 for the protein is very high, evidencing its importance for the hDjC20 structure.
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Affiliation(s)
| | - Arthur Alexandre Pereira
- São Carlos Institute of Chemistry, University of São Paulo - USP, 13560-970 São Carlos, SP, Brazil
| | - Sabrina Dorta Oliveira
- São Carlos Institute of Chemistry, University of São Paulo - USP, 13560-970 São Carlos, SP, Brazil
| | | | | | | | | | | | | | - Thiago Vagas Seraphim
- São Carlos Institute of Chemistry, University of São Paulo - USP, 13560-970 São Carlos, SP, Brazil
| | - Júlio César Borges
- São Carlos Institute of Chemistry, University of São Paulo - USP, 13560-970 São Carlos, SP, Brazil.
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