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Interactions between the Dengue Virus Polymerase NS5 and Stem-Loop A
Paul J Bujalowski1, Wlodzimierz Bujalowski1, Kyung H Choi2
1Department of Biochemistry and Molecular Biology, Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, Texas, USA.
Journal of Virology
|March 31, 2017
Summary
Dengue virus NS5 polymerase binds stem-loop A (SLA) with 1:1 stoichiometry, an entropy-driven process influenced by magnesium concentration. This interaction is crucial for viral replication and offers a target for antiviral therapies.
Area of Science:
- Virology
- Molecular Biology
- Biochemistry
Background:
- Dengue virus replication mechanisms are not fully understood.
- Stem-loop A (SLA) in the 5' UTR is vital for initiating replication by binding the viral polymerase NS5.
- Quantitative data on NS5-SLA interactions in solution are lacking.
Purpose of the Study:
- To quantitatively analyze the interaction between dengue virus NS5 and SLA in solution.
- To investigate the influence of solution conditions on SLA structure and NS5-SLA complex formation.
- To characterize the stoichiometry, binding affinity, and thermodynamic parameters of the NS5-SLA interaction.
Main Methods:
- Isothermal titration calorimetry (ITC) to determine binding stoichiometry and thermodynamics.
- Analytical ultracentrifugation to assess complex size and shape.
- Competition assays to study binding site interactions with single-stranded RNA (ssRNA).
Main Results:
- Dengue virus NS5 binds SLA with a 1:1 stoichiometry.
- The association reaction is primarily entropy-driven.
- NS5-SLA binding is optimal at 1 mM MgCl2 and is sensitive to magnesium and sodium ion concentrations.
- SLA competes with ssRNA for the same binding site on NS5.
- NS5 binds SLAs from different dengue serotypes, indicating recognition of overall shape and specific nucleotides.
Conclusions:
- The quantitative characterization of NS5-SLA interactions provides critical insights into dengue virus replication.
- Understanding these interactions is essential for designing effective antiviral therapeutics targeting viral RNA synthesis.
- The findings highlight the importance of solution conditions, particularly magnesium concentration, in modulating NS5-SLA binding.