The Fusion Protein Specificity of the Parainfluenza Virus Hemagglutinin-Neuraminidase Protein Is Not Solely Defined by the Primary Structure of Its Stalk Domain

Abstract

Virus-specific interaction between the attachment protein (HN) and the fusion protein (F) is prerequisite for the induction of membrane fusion by parainfluenza viruses. This HN-F interaction presumably is mediated by particular amino acids in the HN stalk domain and those in the F head domain. We found in the present study, however, that a simian virus 41 (SV41) F-specific chimeric HPIV2 HN protein, SCA, whose cytoplasmic, transmembrane, and stalk domains were derived from the SV41 HN protein, could not induce cell-cell fusion of BHK-21 cells when coexpressed with an SV41 HN-specific chimeric PIV5 F protein, no. 36. Similarly, a headless form of the SV41 HN protein failed to induce fusion with chimera no. 36, whereas it was able to induce fusion with the SV41 F protein. Interestingly, replacement of 13 amino acids of the SCA head domain, which are located at or around the dimer interface of the head domain, with SV41 HN counterparts resulted in a chimeric HN protein, SCA-RII, which induced fusion with chimera no. 36 but not with the SV41 F protein. More interestingly, retroreplacement of 11 out of the 13 amino acids of SCA-RII with the SCA counterparts resulted in another chimeric HN protein, IM18, which induced fusion either with chimera no. 36 or with the SV41 F protein, similar to the SV41 HN protein. Thus, we conclude that the F protein specificity of the HN protein that is observed in the fusion event is not solely defined by the primary structure of the HN stalk domain. IMPORTANCEIt is appreciated that the HN head domain initially conceals the HN stalk domain but exposes it after the head domain has bound to the receptors, which allows particular amino acids in the stalk domain to interact with the F protein and trigger it to induce fusion. However, other regulatory roles of the HN head domain in the fusion event have been ill defined. We have shown in the current study that removal of the head domain or amino acid substitutions in a particular region of the head domain drastically change the F protein specificity of the HN protein, suggesting that the ability of a given HN protein to interact with an F protein is defined not only by the primary structure of the HN stalk domain but also by its conformation. This notion seems to account for the unidirectional substitutability among rubulavirus HN proteins in triggering noncognate F proteins.T he parainfluenza viruses are classified into the genera Rubulavirus, Avulavirus, and Respirovirus in the family Paramyxoviridae (1, 2). Human parainfluenza virus 1 (HPIV1) and HPIV3 are members of the genus Respirovirus, while HPIV2, HPIV4A, HPIV4B, Simian virus 41 (SV41), and Parainfluenza virus 5 (PIV5) belong to the genus Rubulavirus; Mumps virus (MuV) is not a parainfluenza virus but is a member of the latter genus (1). Newcastle disease virus (NDV) is one of the 10 avian paramyxoviruses of the genus Avulavirus (1). These viruses have two kinds of glycoprotein spikes on the envelope: hemagglutinin-neuraminidase (HN) protein tetramers and fusion (F) protein ...

Multiple Strategies Reveal a Bidentate Interaction between the Nipah Virus Attachment and Fusion Glycoproteins

“…Alteration of the domain of residues 84 to 105 in NDV HN reduces both F interactions and fusion (28), with mutations to the specific HN residues 89, 90, and 94 producing decreased F interactions (32). A region in the PIV5/SV41/ human PIV2 (hPIV2) HN head also appears to play a role in keeping the HN stalk in a conformation favorable for F triggering though the head itself does not appear to be directly interacting with F (23,55). Additionally, complementation studies using MeV and canine distemper virus (CDV) showed that residues 110 to 114 in the MeV H stalk allow specificity for CDV F (56).…”

Different Origins of Newcastle Disease Virus Hemagglutinin-Neuraminidase Protein Modulate the Replication Efficiency and Pathogenicity of the Virus

“…Sequence analysis of the HN protein revealed that there was low amino acid sequence identity (33.4%) between the APMV-2 Yucaipa and NDV SG10 strains, the residues at position 89 and 94 of IR region were also different between Yucaipa and other four viruses, which could be a possible reason for the decline of the fusion activity and virulence of the recombinant virus rSG10-YuHN. It is also reported that the conformation of the HN stalk domain in other paramyxoviruses could influence the interaction of HN protein with F protein in the cell-cell fusion ( Tsurudome et al, 2015 ). Whether this notion is applicable to NDV HN proteins needs to be further investigated.…”

The Hemagglutinin-Neuraminidase (HN) Head Domain and the Fusion (F) Protein Stalk Domain of the Parainfluenza Viruses Affect the Specificity of the HN-F Interaction

“…Since the headless HN proteins of PIV5, SV41, NDV, and MuV have been found to efficiently activate their cognate F proteins and induce extensive cell–cell fusion ( Bose et al, 2012 , 2014 ; Tsurudome et al, 2015 ), the HN stalk domain seems to harbor sufficient elements for interacting with the F protein and activating it. However, we have recently found that the primary structures of the HN stalk domains cannot explain the unidirectional substitutability among the rubulavirus HN proteins ( Tsurudome et al, 2015 ).…”

“…Since the headless HN proteins of PIV5, SV41, NDV, and MuV have been found to efficiently activate their cognate F proteins and induce extensive cell–cell fusion ( Bose et al, 2012 , 2014 ; Tsurudome et al, 2015 ), the HN stalk domain seems to harbor sufficient elements for interacting with the F protein and activating it. However, we have recently found that the primary structures of the HN stalk domains cannot explain the unidirectional substitutability among the rubulavirus HN proteins ( Tsurudome et al, 2015 ). We also found that replacement of specified amino acids at or around the dimer interfaces of the HN head domain remarkably modify the F protein specificity, suggesting that changes in the head domain structure somehow alter the conformation of the stalk domain, thereby converting the F protein specificity ( Tsurudome et al, 2015 ).…”

“…However, we have recently found that the primary structures of the HN stalk domains cannot explain the unidirectional substitutability among the rubulavirus HN proteins ( Tsurudome et al, 2015 ). We also found that replacement of specified amino acids at or around the dimer interfaces of the HN head domain remarkably modify the F protein specificity, suggesting that changes in the head domain structure somehow alter the conformation of the stalk domain, thereby converting the F protein specificity ( Tsurudome et al, 2015 ).…”