Human HSPA9 (mtHsp70, mortalin) interacts with lipid bilayers containing cardiolipin, a major component of the inner mitochondrial membrane

Author(s)

Dores-Silva, Paulo Roberto ^{[1, 2]} ; Cauvi, David M. ^[2] ; Kiraly, Vanessa T. R. ^[1] ; Borges, Julio C. ^[1] ; De Maio, Antonio ^{[2, 3]}

Affiliation

^[1] Univ Sao Paulo, Sao Carlos Inst Chem, Sao Paulo - Brazil

^[2] Univ Calif San Diego, Sch Med, Dept Surg, Div Trauma Crit Care Burns & Acute Care Surg, La Jolla, CA 92093 - USA

^[3] Univ Calif San Diego, Sch Med, Dept Neurosci, Div Trauma Crit Care Burns & Acute Care Surg, La Jolla, CA 92093 - USA

• Document type: Journal article
• Source: BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES; v. 1862, n. 11 NOV 1 2020.
• Web of Science Citations: 0

Abstract

Mitochondrial Hsp70 (HSPA9, mtHsp70, mortalin) in conjunction with a complex set of other proteins is involved in the transport of polypeptides across the mitochondrial matrix. This observation allows us to hypothesize that HSPA9 might interact with membranes directly, similarly to other Hsp70s. Thus, we investigated whether human HSPA9 could also get inserted into lipid membranes. Human HSPA9 was incubated with liposomes made of lipids found within the mitochondrial membrane, such as 1', 3'-bis {[}1, 2-dimyristoyl-sn-glycero-3-phospho]-glycerol (CL), palmitoyl-oleoyl phosphocholine (POPC), palmitoyl-oleoyl phosphoserine (POPS), and palmitoyl-oleoyl phosphoethanolamine (POPE). HSPA9 displayed a predilection for CL and POPS, and low affinity for POPC and POPE, suggesting that the proteins have high specificity for negatively charged phospholipids. Then, liposomes were made with a composition resembling either the outer or inner mitochondrial membrane (OMM or IMM, respectively). We observed that HSPA9 has a higher affinity for IMM than OMM, which is consistent with the higher content of CL in the IMM. A comparison for the incorporation into POPS or CL liposomes by HSPA9 or HSPA1 indicated that both proteins behaved very similarly when exposed to CL liposomes, but differently with POPS liposomes, which was further corroborated by their susceptibility to proteinase K digestion after incorporation into liposomes. The measurement of thermodynamic parameters also showed that the interaction of both proteins with CL and POPS liposomes was different. Overall, our data showed that HSPA9 is prone to interact with membranes resembling the IMM that may be important for its role in the translocation of proteins into the mitochondria. (AU)

• FAPESP's process: 16/22477-1 - Human mortalin: interaction with liposomes, mitochondrion membrane, beta-amyloids and effect of their presence in the toxicity of beta-amyloids on neurons
• Grantee: Paulo Roberto das Dores da Silva
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 17/07335-9 - Studies of human HSP70 isoforms residing in the cytoplasm and mitochondria and their high molecular weight oligomers: interaction with co-chaperones and client proteins
• Grantee: Julio Cesar Borges
• Support Opportunities: Regular Research Grants
• FAPESP's process: 14/16646-0 - Human mortalin: interaction with co-chaperones, p53 and mutants, aggregation kinectics, regulation/modulation and vesicle secretion
• Grantee: Paulo Roberto das Dores da Silva
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 12/50161-8 - Study of the structure and function of the Hsp90 chaperone with emphasis on its role in cellular homeostasis
• Grantee: Carlos Henrique Inacio Ramos
• Support Opportunities: Research Projects - Thematic Grants