Quantitation of Hsp104-mediated curing of [PSI+] as well as the quantitative assessment of [PSI+] formation upon Sup35 overexpression were performed as described [32].
We also observe that high levels of Sse1, but not of an unrelated NEF, very potently inhibit Hsp104-mediated curing of [PSI+].
We quantitated the effect of Ssa1, Ssb1, Sse1 and Snl1ΔN overexpression on Hsp104-mediated curing of both a weak and a strong [PSI+] strain (Fig. 3A, B).
However, mutational analysis has led to the suggestion that Hsp104-mediated curing of [PSI+] may not solely be the result of aggregate fragmentation, but involves a distinct activity requiring additional functional domains of Hsp104 [16], [16].
The present study reports that γ-inulin treatment is highly effective in elevating PDT-mediated cures of mouse tumours and reveals that its action amplifies CTL activity against PDT-treated tumours.
In addition, the potent inhibition of Hsp104-mediated curing by Sse1 may account for prion stability upon physiological Hsp104 induction; a role also proposed for Ssa1 [21].
Indeed, combined overexpression of Ssa1 and Sse1 further inhibited curing, although the co-expression of both Sse1 and Ssb1 lessened the increase in Hsp104-mediated curing as compared to Ssb1 alone.
First, Sse1 activities differ from those of Snl1ΔN in the inhibition of Hsp104-mediated curing.
The increased effectiveness of Sse1 over Ssa1 in inhibiting Hsp104-mediated curing may be the result of an insufficient endogenous NEF activity that is rate-limiting for Hsp70 activities.
In contrast to formation and propagation of [PSI+], however, Hsp104-mediated curing may represent a situation where de novo seed formation is more relevant.
The final Sup35 species generated by the Hsp104-mediated curing process cannot seed in vitro polymer formation [14].
