Differential Behaviours and Preferential Bindings of Influenza Nucleoproteins on Importins-α

Abstract

Influenza viruses are negative single-stranded RNA viruses with nuclear transcription and replication. They enter the nucleus by using the cellular importin-α/-β nuclear import machinery. Influenza nucleoproteins from influenza A, B, C and D viruses possess a nuclear localization signal (NLS) localized on an intrinsically disordered extremity (NPTAIL). In this paper, using size exclusion chromatography (SEC), SEC-multi-angle laser light scattering (SEC-MALLS) analysis, surface plasmon resonance (SPR) and fluorescence anisotropy, we provide the first comparative study designed to dissect the interaction between the four NPTAILs and four importins-α identified as partners. All interactions between NPTAILs and importins-α have high association and dissociation rates and present a distinct and specific behaviour. D/NPTAIL interacts strongly with all importins-α while B/NPTAIL shows weak affinity for importins-α. A/NPTAIL and C/NPTAIL present preferential importin-α partners. Mutations in B/NPTAIL and D/NPTAIL show a loss of importin-α binding, confirming key NLS residues. Taken together, our results provide essential highlights of this complex translocation mechanism.

Existing Evidence for Influenza B Virus Adaptations to Drive Replication in Humans as the Primary Host

“…Once the gene segments reach the nucleus, the virus usurps host factors to cross the nuclear envelope. The host factor importin-α binds three overlapping NLS on the N-terminal tail of B-NP to facilitate nuclear transport [ 51 , 52 ]. Importin-α has been previously described as a species-determinant for IAV [ 12 , 53 ].…”

“…To determine if a host restriction phenomenon has been observed during IBV genome replication, we considered host nuclear factors. The importin-α protein family has been identified as a critical factor for transporting the vRNPs from the cytoplasm into the nucleus [ 51 , 52 ]. However, current literature only highlights the interaction between IBV vRNPs and human importin-α.…”

How SARS-CoV-2 and Other Viruses Build an Invasion Route to Hijack the Host Nucleocytoplasmic Trafficking System

“…Therefore, the non-classical NLS of an NP is essential for IAV replication [173]. Donchet et al reported the binding affinity of an NP to different α-importins; an NP had the highest affinity for importin-α7 and the lowest affinity for importin-α1 [174].…”

Special Issue “Function and Structure of Viral Ribonucleoproteins Complexes”

“…Viral nucleoproteins from influenza A, B, C and D viruses possess a nuclear localization signal (NLS) localized on an intrinsically disordered extremity of nucleoproteins (NP TAIL ). In their work, Crepin and collaborators provided the first comparative study to dissect the interactions between the four NP TAILs and the four importins-α identified and provided important highlights of these complex translocation mechanisms [9].…”