Abstract

The recently discovered 340-cavity in influenza neuraminidase (NA) N6 and N7 subtypes has introduced new possibilities for rational structure-based drug design. However, the plasticity of the 340-loop (residues 342–347) and the role of the 340-loop in NA activity and substrate binding have not been deeply exploited. Here, we investigate the mechanism of 340-cavity formation and demonstrate for the first time that seven of nine NA subtypes are able to adopt an open 340-cavity over 1.8 μs total molecular dynamics simulation time. The finding that the 340-loop plays a role in the sialic acid binding pathway suggests that the 340-cavity can function as a druggable pocket. Comparing the open and closed conformations of the 340-loop, the side chain orientation of residue 344 was found to govern the formation of the 340-cavity. Additionally, the conserved calcium ion was found to substantially influence the stability of the 340-loop. Our study provides dynamical evidence supporting the 340-cavity as a druggable hotspot at the atomic level and offers new structural insight in designing antiviral drugs.

Highlights

  • Since the beginning of the last century, multiple pandemics caused by influenza viruses have severely impacted public health [1]

  • Our study reveals that seven of the nine NA subtypes exhibit an open 340-cavity, the calcium ion plays an important role in maintaining the conformation of the 340-loop, and the 340-loop is a canonical approach site in the sialic acid (SA) binding mechanism

  • Our results indicate that the 340-loop is a critical motif in NA, and the 340-cavity is a valuable hotspot for anti-influenza drug design

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Summary

Introduction

Since the beginning of the last century, multiple pandemics caused by influenza viruses have severely impacted public health [1]. Exploring the structural features of NAs and identifying the SA binding path are of great importance in designing anti-influenza drugs [7,8]. The crystal structures of group-1 NAs contain a unique characteristic, the 150-cavity, which can be exploited to develop new anti-influenza drugs [10]. Questions regarding whether the 340-cavity is prevalent in NAs, whether the 340-loop participates in the substrate binding process, and the structural dynamics of the 340-loop in other NA subtypes have never been explored. Our study reveals that seven of the nine NA subtypes exhibit an open 340-cavity, the calcium ion plays an important role in maintaining the conformation of the 340-loop, and the 340-loop is a canonical approach site in the SA binding mechanism. Our results indicate that the 340-loop is a critical motif in NA, and the 340-cavity is a valuable hotspot for anti-influenza drug design

Results
The 340-Loop Is Involved in the SA Binding Pathway
A Calcium Ion Controls the Stability of the 340-Loop
Discussion
MD Simulation Details
Sliding Binding-Box Docking

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