Inhibition of Simian Virus 40 replication by targeting the molecular chaperone function and ATPase activity of T antigen

Abstract

Polyomaviruses such as BK virus and JC virus have been linked to several diseases, but treatments that thwart their propagation are limited in part because of slow growth and cumbersome culturing conditions. In contrast, the replication of one member of this family, Simian Virus 40 (SV40), is robust and has been well-characterized. SV40 replication requires two domains within the viral-encoded large tumor antigen (TAg): The ATPase domain and the N-terminal J domain, which stimulates the ATPase activity of the Hsp70 chaperone. To assess whether inhibitors of polyomavirus replication could be identified, we examined a recently described library of small molecules, some of which inhibit chaperone function. One compound, MAL2-11B, inhibited both TAg’s endogenous ATPase activity and the TAg-mediated activation of Hsp70. MAL2-11B also reduced SV40 propagation in plaque assays and compromised DNA replication in cell culture and in vitro. Furthermore, the compound significantly reduced the growth of BK virus in a human kidney cell line. These data indicate that pharmacological inhibition of TAg’s chaperone and ATPase activities may provide a route to combat polyomavirus-mediated disease.

Chemical methodology as a source of small-molecule checkpoint inhibitors and heat shock protein 70 (Hsp70) modulators

“…To date, six libraries based on MAL3-101 and an earlier design have been obtained, resulting in ∼500 analogs. We have found distinct, and often independent, SARs for each pharmacological activity (4,30,31,32).…”

“…MAL3-101 itself also inhibited the replication of a Trypanosome species that causes sleeping sickness (29). Finally, MAL2-11B, an intermediate in the synthesis of MAL3-101, inhibited the ATPase activity of Hsp70 as well as the ATPase activity of a chaperone-like protein, T antigen, which is required for polyomavirus (PyV) replication (32). Infection by members of the PyV family contribute to AIDSrelated dementias and renal transplant rejection (33).…”

“…Interestingly, MAL3-101 had little effect on PyV replication. MAL2-11B also reduced the growth of a human polyomavirus (BK virus) in kidney cells, as measured by assaying the levels of viral DNA, with no apparent effect on cell viability (32). To optimize the antiviral activity and properties of the MAL2-11B series of pyrimidinones, and to develop a SAR, we incorporated isosteric replacements for the carboxylic acid groups.…”

The Effect of Structure and Mechanism of the Hsp70 Chaperone on the Ability to Identify Chemical Modulators and Therapeutics

“…MAL3-101 (Scheme 2) was one member of a~360 compound library and was identified as a novel modulator of Hsp70 activity in 2004 [206]. Specifically, we established that MAL3-101 had a minor stimulatory effect on the K cat for ATP hydrolysis (see also [209]), but more intriguingly, it significantly reduced the ability of Hsp40 co-chaperones to enhance the ATPase activity of Hsp70 in singleturnover studies [210]. Specifically, MAL3-101 at 300 μM decreased the rate of T antigen-stimulated Hsp70 ATPase hydrolysis approximately fourfold, from 13 Â 10 3 to 3 Â 10 3 %ATP hydrolyzed/s [196].…”

“…Dihydropyrimidinone-based inhibitors of the Hsp40-stimulated activity of Hsp70 inhibit breast cancer cell proliferation [210,213], possess synergistic effects A. Manos-Turvey et al on multiple myeloma cell growth when examined with Hsp90 or proteasome inhibitors [214], and prevent the replication of polyomaviruses [209,215], which recruit Hsp70 to an oncogenic protein that is encoded by the viral genome. MAL3-101 and its structural analogs have also served as in vitro probes for Hsp70 function.…”