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Hsp70 ATP-dependent dimerization and Chaperone/Co-chaperone Interactions

ABSTRACT: Eukaryotic protein homeostasis (proteostasis) is largely dependent on the action of highly conserved Hsp70 molecular chaperones. Recent evidence indicates that apart from conserved molecular allostery, Hsp70 proteins retained and adapted throughout the evolution the ability to assemble as functionally relevant ATP-bound dimers. Here we have compared the ATP-dependent dimerization of DnaK, human stress-inducible Hsp70, Hsc70 and BiP Hsp70 proteins showing that their dimerization propensities differ with stress-inducible Hsp70 being predominantly dimeric in the presence of ATP. The structural analyses using hydrogen/deuterium exchange mass spectrometry, native electrospray ionization mass spectrometry, chemical cross-linking and small-angle X-ray scattering revealed that stress-inducible Hsp70 assembles in solution as an antiparallel dimer with the intermolecular interface closely resembling the ATP-bound dimer interfaces captured in DnaK and BiP crystal structures. ATP-dependent dimerization of stress-inducible Hsp70 is necessary for its efficient interaction with Hsp40 as shown by experiments with dimerization-deficient mutants. Moreover, dimerization of ATP-bound Hsp70 is required for its participation in high molecular weight protein complexes detected ex vivo supporting its functional role in vivo. As human cytosolic Hsp70 has the ability to interact with tetratricopeptide repeat (TPR) domain containing co-chaperones, we tested the interaction of Hsp70 ATP-dependent dimer with Chip and Tomm34 co-chaperones. While Chip associates with intact Hsp70 dimer to form a larger complex, binding of Tomm34 disrupts Hsp70 dimer and this event plays an important role in Hsp70 activity regulation. In summary, this study provides structural evidence of robust ATP-dependent antiparallel dimerization of human inducible Hsp70 protein and suggests novel role of TPR domain co-chaperones in multichaperone complexes involving Hsp70 ATP-bound dimers.

INSTRUMENT(S): solariX

ORGANISM(S): Homo Sapiens (human)

SUBMITTER: Petr Man

LAB HEAD: Petr Man

PROVIDER: PXD010069 | Pride | 2018-12-11

REPOSITORIES: Pride

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Publications

Human Stress-inducible Hsp70 Has a High Propensity to Form ATP-dependent Antiparallel Dimers That Are Differentially Regulated by Cochaperone Binding.

Trcka Filip F Durech Michal M Vankova Pavla P Chmelik Josef J Martinkova Veronika V Hausner Jiri J Kadek Alan A Marcoux Julien J Klumpler Tomas T Vojtesek Borivoj B Muller Petr P Man Petr P

Molecular & cellular proteomics : MCP 20181120 2

Eukaryotic protein homeostasis (proteostasis) is largely dependent on the action of highly conserved Hsp70 molecular chaperones. Recent evidence indicates that, apart from conserved molecular allostery, Hsp70 proteins have retained and adapted the ability to assemble as functionally relevant ATP-bound dimers throughout evolution. Here, we have compared the ATP-dependent dimerization of DnaK, human stress-inducible Hsp70, Hsc70 and BiP Hsp70 proteins, showing that their dimerization propensities ...[more]

PMID: 30459217

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Project description:The major inducible 70 kDa heat shock protein (hsp70) is host protective in a mouse model of measles virus (MeV) brain infection. Transgenic constitutive expression of hsp70 in neurons, the primary target of MeV infection, abrogates neurovirulence in neonatal H-2d congenic C57BL/6 mice. A significant level of protection is retained after depletion of T lymphocytes, implicating innate immune mechanisms. Focus of the present work was to elucidate the basis for hsp70-dependent innate immunity using this model. Transcriptome analysis of brains from transgenic (TG) and non-transgenic (NT) mice 5 days after infection identified type 1 interferon (IFN) signaling and macrophage activation/antigen presentation as the main differences linked to survival. The pivotal role for type 1 IFN in hsp70-mediated protection was demonstrated in mice with a genetically disrupted type 1 IFN receptor (IFNAR-/-), where IFNAR-/- eliminated the difference in survival between TG and NT mice. Brain macrophages, not neurons, are the predominant source of type 1 IFN in the virus-infected brain, and in vitro studies provided a mechanistic basis by which MeV-infected neurons can induce IFN-β in uninfected microglia in an hsp70-dependent manner. MeV infection induced extracellular release of hsp70 from mouse neuronal cells that constitutively express hsp70, and extracellular hsp70 induced IFN-β transcription in mouse microglial cells through Toll-like receptors 2 and 4. Collectively, results support a novel axis of type 1 IFN-dependent antiviral immunity in the virus-infected brain that is driven by hsp70. Hsp70 expression in mice enhances gene expression related to antiviral immune response against MeV neurovirulence. We performed microarrays on whole brain tissues in mice to obtain an unbiased picture of how hsp70 alters host innate responses to viral infection. Hsp70-overexpressing transgenic (TG) and non-transgenic (NT) mice were infected with MeV intracranially, and total brain mRNA harvested at 5 and 10 days post infection (d.p.i.) was analyzed, sampling the hemisphere opposite the side of viral inoculation. Analysis includes 6 groups: infected TG at 5 d.p.i. (n=4), infected TG at 10 d.p.i. (n=5), infected NT at 5 d.p.i. (n=4), infected NT at 10 d.p.i. (n=5), uninfected TG at 5 d.p.i. (n=4), and uninfected NT at 5 d.p.i. (n=4).

Dataset Information

Hsp70 ATP-dependent dimerization and Chaperone/Co-chaperone Interactions

Publications

Human Stress-inducible Hsp70 Has a High Propensity to Form ATP-dependent Antiparallel Dimers That Are Differentially Regulated by Cochaperone Binding.

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