1 research outputs found
Nematode Sgt1-Homologue D1054.3 Binds Open and Closed Conformations of Hsp90 via Distinct Binding Sites
Heat shock protein 90 (Hsp90) is
a highly conserved ATP-driven
machine involved in client protein maturation, folding, and activation.
The chaperone is supported by a set of cochaperones that confer client
specificities. One of those proteins is the suppressor of G2 allele
of <i>skp1</i> (Sgt1), which participates together with
Hsp90 in the immune responses of plants. Sgt1 consists of three domains:
a TPR-, CS-, and SGS-domain, conserved in plants, yeast, and humans.
The TPR-domain though is lacking in nematodes and insects. We observe
that the <i>Caenorhabditis elegans</i> Sgt1 homologue D1054.3
binds to Hsp90 in the absence of nucleotides but much stronger in
the presence of ATP and ATPγS. The latter binding mode is similar
to p23, another CS-domain containing Hsp90 cofactor, even though binding
is not observable for p23 in the absence of nucleotides. We use point
mutations in Hsp90, which accumulate different conformations in the
ATPase cycle, to differentiate between binding to open and closed
Hsp90 conformations. These data support a strong contribution of the
Hsp90 conformation to Sgt1 binding and highlight the ability of this
cofactor to interact with all known Hsp90 conformations albeit with
different affinities