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PDBsum entry 4hse
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References listed in PDB file
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Key reference
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Title
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The molecular mechanism of hsp100 chaperone inhibition by the prion curing agent guanidinium chloride.
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Authors
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C.Zeymer,
N.D.Werbeck,
I.Schlichting,
J.Reinstein.
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Ref.
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J Biol Chem, 2013,
288,
7065-7076.
[DOI no: ]
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PubMed id
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Abstract
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The Hsp100 chaperones ClpB and Hsp104 utilize the energy from ATP hydrolysis to
reactivate aggregated proteins in concert with the DnaK/Hsp70 chaperone system,
thereby playing an important role in protein quality control. They belong to the
family of AAA+ proteins (ATPases associated with various cellular activities),
possess two nucleotide binding domains per monomer (NBD1 and NBD2), and
oligomerize into hexameric ring complexes. Furthermore, Hsp104 is involved in
yeast prion propagation and inheritance. It is well established that low
concentrations of guanidinium chloride (GdmCl) inhibit the ATPase activity of
Hsp104, leading to so called "prion curing," the loss of prion-related
phenotypes. Here, we present mechanistic details about the Hsp100 chaperone
inhibition by GdmCl using the Hsp104 homolog ClpB from Thermus thermophilus.
Initially, we demonstrate that NBD1 of ClpB, which was previously considered
inactive as a separately expressed construct, is a fully active ATPase on its
own. Next, we show that only NBD1, but not NBD2, is affected by GdmCl. We
present a crystal structure of ClpB NBD1 in complex with GdmCl and ADP, showing
that the Gdm ion binds specifically to the active site of NBD1. A conserved
essential glutamate residue is involved in this interaction. Additionally, Gdm
interacts directly with the nucleotide, thereby increasing the nucleotide
binding affinity of NBD1. We propose that both the interference with the
essential glutamate and the modulation of nucleotide binding properties in NBD1
is responsible for the GdmCl-specific inhibition of Hsp100 chaperones.
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