Tuberous sclerosis
complex (TSC) is a neurological syndrome manifested
by non-cancerous tumors in several organs. Mutations in either
TSC1
or
TSC2
tumor suppressor gene cause
the disease. In the cell, TSC1 is known to form a heterodimer with
TSC2 because of which an active complex is formed that negatively
regulates the mTORC1 activity during cellular stress. Hence, mutation in
TSC1
or
TSC2
is manifested by excess proliferation of the cells
leading to the development of numerous benign tumors. The TSC1 and
TSC2 complex is known to interact with several protein-binding partners.
One such significant interaction of this complex is with the molecular
chaperone HSP70. The role of TSC1 in that interaction is still elusive.
Here, we have expressed and purified TSC1 (302–420 residues)
in a bacterial expression system and have shown that this region directly
interacts with HSP70. We have shown that TSC1 increases the ATPase
activity of
Escherichia coli
DnaK,
a HSP70 homologue. On the contrary, TSC1 was found to show inhibitory
activity toward human HSP70. Our result suggests that TSC1 (302–420
aa) shows differential interaction between the HSP70 homologues. This
points toward the evolutionary significance of chaperoning system
and the importance of eukaryotic tetratricopeptide repeat domain interaction
motif -EEVD. Our study shows the evidence that TSC1 interacts with
HSP70 and has a role to play in the chaperoning activity to maintain
cellular homeostasis.