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High-throughput Antiviral Assays to Screen for Inhibitors of Zika Virus Replication
Published on: October 30, 2021
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Dual function of Zika virus NS2B-NS3 protease
Sergey A Shiryaev1, Piotr Cieplak1, Anton Cheltsov2
1Sanford-Burnham-Prebys Medical Discovery Institute, Infectious and Inflammatory Disease Center, La Jolla, California, United States of America.
Plos Pathogens
|November 27, 2023
Summary
Zika virus NS2B-NS3 protease binds RNA in an open conformation, not closed or super-open states. This suggests a novel RNA-binding role for the viral helicase-protease complex.
Area of Science:
- Virology
- Molecular Biology
- Structural Biology
Background:
- Zika virus (ZIKV) serine protease, crucial for viral replication, comprises NS2B and NS3pro.
- The NS3 helicase domain (NS3hel) is vital for helicase activity and ATP binding.
Purpose of the Study:
- To investigate the novel RNA-binding function of ZIKV NS2B-NS3pro.
- To elucidate the conformational states of NS2B-NS3pro involved in RNA binding and protease activity.
Main Methods:
- Biochemical assays to test RNA binding affinity (Kd) of ZIKV NS2B-NS3pro.
- Structural analysis of NS2B-NS3pro in different conformations (closed, open, super-open).
- Modeling of the open conformation using homologous dengue virus NS2B-NS3pro.
Main Results:
- ZIKV NS2B-NS3pro binds single-stranded RNA with a Kd of ~0.3 μM.
- RNA binding is abolished in the closed (proteolytically active) and super-open conformations.
- RNA binding occurs in the open conformation, facilitated by conserved positively charged structures.
Conclusions:
- ZIKV NS2B-NS3pro possesses a novel RNA-binding function dependent on its open conformation.
- A 'reverse inchworm' model is proposed for the intertwined helicase-protease machinery, involving conformational cycling.
- Substrate-induced transition to the closed conformation enables protease activity.
