posted on 2024-02-06, 06:29authored byMarkus Zehe, Josef Kehrein, Curd Schollmayer, Christina Plank, Helena Kovacs, Eduardo Merino Asumendi, Ulrike Holzgrabe, Clemens Grimm, Christoph Sotriffer
Heat shock protein 70 (Hsp70) isoforms
are key players in the regulation
of protein homeostasis and cell death pathways and are therefore attractive
targets in cancer research. Developing nucleotide-competitive inhibitors
or allosteric modulators, however, has turned out to be very challenging
for this protein family, and no Hsp70-directed therapeutics have so
far become available. As the field could profit from alternative starting
points for inhibitor development, we present the results of a fragment-based
screening approach on a two-domain Hsp70 construct using in-solution
NMR methods, together with X-ray-crystallographic investigations and
mixed-solvent molecular dynamics simulations. The screening protocol
resulted in hits on both domains. In particular, fragment binding
in a deeply buried pocket at the substrate-binding domain could be
detected. The corresponding site is known to be important for communication
between the nucleotide-binding and substrate-binding domains of Hsp70
proteins. The main fragment identified at this position also offers
an interesting starting point for the development of a dual Hsp70/Hsp90
inhibitor.