Crystal Structure of Herpes Simplex Virus 2 gD Bound to Nectin-1 Reveals a Conserved Mode of Receptor Recognition

Abstract

Herpes simplex virus 1 (HSV-1) and HSV-2 are among the most prevalent human pathogens. Both viruses can recognize, via the surface envelope glycoprotein D (gD), human nectin-1 as a functional receptor. Previous studies have successfully elucidated the molecular basis of the binding between HSV-1 gD and nectin-1 by cocrystallography. Despite a high sequence identity between HSV-1 and HSV-2 gDs, the atomic intermolecule details for the HSV-2-gD/nectin-1 interaction remain elusive. Here, we report the crystal structures of both the unbound and the nectin-1-bound HSV-2 gDs. The free-gD structure expectedly comprises an IgV-like core and the surface-exposed terminal extensions as observed in its HSV-1 counterpart but lacks traceable electron densities for a large portion of the terminal elements. These terminal residues were clearly traced in the complex structure as a definitive loop in the N terminus and an ␣-helix in the C terminus, thereby showing a conserved nectin-1-binding mode as reported for HSV-1 gD. The interface residues in nectin-1 were further mutated and tested for the gD interaction by surface plasmon resonance. The resultant binding patterns were similar for HSV-1 and HSV-2 gDs, further supporting a homologous receptor-binding basis by the two viruses for nectin-1. These data, together with a cell-based fusion assay showing a cross-inhibition of the gD/nectin-1-mediated cell-cell fusion by soluble HSV-1 and HSV-2 gDs, provided solid structural and functional evidence that HSV-1 and HSV-2 recognize nectin-1 via the same binding mode. Finally, we also demonstrated that nectin-1 I80 is an important residue involved in gD interaction. IMPORTANCEDespite intensified studies, a detailed picture of the molecular features in the HSV-2-gD/nectin-1 interaction remains unavailable. Previous work focused on HSV-1 gD, which folds into an IgV-like core with large terminal extensions and utilizes the extension elements to engage nectin-1. Here, we report the crystal structures of HSV-2 gD in both the free and the nectin-1-bound forms. The atomic intermolecule details for HSV-2-gD/nectin-1 interaction are clearly presented. The observed binding mode is identical to that reported for its HSV-1 counterpart. This structural observation was further supported by our comparative functional assays showing that nectin-1 mutations similarly affect the ligand-receptor interaction of both virus gDs. Taken together, we provide comprehensive structural and functional data demonstrating a conserved receptor-binding mode between HSV-1 and HSV-2 for nectin-1. Our results also indicate that the tropism difference between the two viruses likely arises from aspects other than the gD/nectin-1 binding features.

Structural basis of nectin-1 recognition by pseudorabies virus glycoprotein D

“…Following the same strategy, we successfully expressed and purified a truncated PRV gD protein spanning residues 1-337 (hereafter referred to as gD337) using a baculovirus expression system (Fig 2A and 2B). Noted that the residue numberings for HSV gD in previous structural studies are based on the mature protein [21,22], the numberings for PRV gD amino CHO-K1 cells were transfected for transient expression of HU-, SW-nectin-1 and HU-HVEM, and subsequently infected with a PRV vaccine strain. Clear cytopathic changes were observed with HU-and SWnectin-1, which are marked with arrows.…”

“…It is demonstrated that the gD proteins of these alphaherpesviruses bind to nectin-1 with nanomolar affinities [13,19]. The detailed binding mode between HSV gD and human nectin-1 has been successfully illustrated in several previous studies [20][21][22]. The gD molecule is composed of a V-set Ig-like (or IgV-like) core and long N-and C-terminal extensions, It utilizes both terminal-extension elements to interact with nectin-1.…”

“…The gD molecule is composed of a V-set Ig-like (or IgV-like) core and long N-and C-terminal extensions, It utilizes both terminal-extension elements to interact with nectin-1. The receptor, with three Ig-like domains arranged into a rod-shaped structure, projects its membrane-distal IgV domain for gD engagement [21][22][23]. It is notable that the whole gD footprint in nectin-1 overlaps extensively with the nectin-1 dimerization interface, which explains a novel mechanism of exploiting the host cell-adhesion functions by HSV for virus spread and infection [21,22].…”

The AGMA1 poly(amidoamine) inhibits the infectivity of herpes simplex virus in cell lines, in human cervicovaginal histocultures, and in vaginally infected mice

“…To this regard, it is important to point out that the side guanidine groups of AGMA1 might reinforce membrane interactions, thanks to their well-known chaotropic properties [28,36,64]. Interestingly are also the observation that the binding of HSV-1 and 2 glycoproteins gD to nectin-1 depends on several basic amino acids, including L25, R36, R134 and R222 [65] and that HSV-2 infection can be mediated by a v b 3 integrin [66] that is well known to bind its physiological or pathological ligand via basic domains [67e69]. Taken together, these data suggest that the high positive charge of AGMA1 may mediate its binding to receptors different from HSPGs, conferring to the polymer a "multitarget" mechanism of action, as already demonstrated for cationic dendrimer-like compounds [70].…”

A Herpes Simplex Virus 2 (HSV-2) gD Mutant Impaired for Neural Tropism Is Superior to an HSV-2 gD Subunit Vaccine To Protect Animals from Challenge with HSV-2

“…HSV gD binds to both HVEM and nectin-1, and this step is essential for HSV infection of cells. The HVEM and nectin-1 binding domains of HSV gD are located in different regions of the glycoprotein: the HVEM binding domain is at the N terminus (26)(27)(28), and the nectin-1 domain is in the middle of HSV gD (28)(29)(30). Mutations in one domain can impair the ability of HSV gD to use one receptor but not the other receptor (28,31,32).…”