Probing the ribosome-dependent mechanisms of human alphacoronavirus Nsp1

Project Summary
The development of specific therapeutics infectious coronaviruses remains a significant challenge and requires
a detailed mechanistic understanding of virus–host cell interactions and viral pathogenesis. A potential target
for therapeutic intervention is the nonstructural protein 1 (Nsp1), a major virulence factor produced by alpha-
and beta-coronavirus (α-, β-CoV) that regulates host gene expression. Nsp1 is a key player in a strategy
deemed “host shutoff,” in which expression pathways are shifted from host to viral genes, allowing for virus
proliferation and immune evasion. Biochemical and structural studies have shown that Nsp1 exerts direct
translational control, in certain cases binding to the 40S ribosomal subunit with nanomolar affinity. The
structurally conserved N-terminal core of the protein is thought to be critical for its function, yet its contribution
to Nsp1’s mechanisms remain unclear. Furthermore, α-CoV Nsp1s only contain and function solely through
this core. Structural studies with Nsp1 and the ribosome together have yet to resolve the Nsp1 N-terminus,
generating a gap in knowledge regarding this domain and the protein’s overall function, and impeding the
development of effective drug candidates targeting Nsp1. The goal of this proposal is to uncover structural
insights into the Nsp1 N-terminal core and establish Nsp1’s specificity in enacting host shut-off, focusing on
Nsp1 proteins in human alpha-coronaviruses. The study will contribute to the long-term goal of understanding
coronavirus pathogenesis and evolution and developing effective therapies against the many prevalent
diseases caused by coronaviruses.

Grant Number: 5F31AI181514-02
NIH Institute/Center: NIH
Principal Investigator: Shravani Balaji