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bioRxiv · 10.64898/2026.01.06.697956

Discovery of a cluster in the PRRSV Nsp1α leader protease reveals host-virus interplay in its downstream functions

Quist, T.·Buzuk, A.·Nguyen, H. T.·Takeoka, K.·Bak, D. W.·Weerapana, E.·Perlstein, D. L.·Pandelia, M.-E.
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Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV; Betaarterivirus suid) is a major global threat to swine production, yet effective antiviral therapies are lacking. The leader protease Nsp1 is essential for viral replication and innate immune suppression, and its N-terminal zinc-finger (ZF) domain is critical for function, although its molecular role remains unclear. Here, we show that the ZF domain plays only a minor role in protease activity and that Nsp1 is largely inactive following release from the polyprotein. Using Mossbauer and UV/visible spectroscopy combined with chemoproteomics, we demonstrate that the ZF site binds not only Zn but also a [4Fe-4S] cluster. Notably, the Fe-S cluster, but not Zn, allosterically modulates residual protease activity. Nsp1 directly engages the cytosolic iron-sulfur cluster assembly machinery via CIAO1 and competes with the Fe-S carrier CIAO3, establishing the [4Fe-4S] cluster as a bona fide cofactor. These findings redefine Nsp1 as an Fe-S-dependent viral protein and reveal new opportunities for metal-targeted antiviral strategies.

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Quist, T., Buzuk, A., Nguyen, H. T., Takeoka, K., Bak, D. W., Weerapana, E., Perlstein, D. L., Pandelia, M.-E.. 2026-01-06. Discovery of a cluster in the PRRSV Nsp1α leader protease reveals host-virus interplay in its downstream functions. https://doi.org/10.64898/2026.01.06.697956

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