Functional Role of N-Linked Glycosylation in Pseudorabies Virus Glycoprotein gH. 2018

Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany.

Many viral envelope proteins are modified by asparagine (N)-linked glycosylation, which can influence their structure, physicochemical properties, intracellular transport, and function. Here, we systematically analyzed the functional relevance of N-linked glycans in the alphaherpesvirus pseudorabies virus (PrV) glycoprotein H (gH), which is an essential component of the conserved core herpesvirus fusion machinery. Upon gD-mediated receptor binding, the heterodimeric complex of gH and gL activates gB to mediate fusion of the viral envelope with the host cell membrane for viral entry. gH contains five potential N-linked glycosylation sites at positions 77, 162, 542, 604, and 627, which were inactivated by conservative mutations (asparagine to glutamine) singly or in combination. The mutated proteins were tested for correct expression and fusion activity. Additionally, the mutated gH genes were inserted into the PrV genome for analysis of function during virus infection. Our results demonstrate that all five sites are glycosylated. Inactivation of the PrV-specific N77 or the conserved N627 resulted in significantly reduced in vitro fusion activity, delayed penetration kinetics, and smaller virus plaques. Moreover, substitution of N627 greatly affected transport of gH in transfected cells, resulting in endoplasmic reticulum (ER) retention and reduced surface expression. In contrast, mutation of N604, which is conserved in the Varicellovirus genus, resulted in enhanced in vitro fusion activity and viral cell-to-cell spread. These results demonstrate a role of the N-glycans in proper localization and function of PrV gH. However, even simultaneous inactivation of all five N-glycosylation sites of gH did not severely inhibit formation of infectious virus particles.IMPORTANCE Herpesvirus infection requires fusion of the viral envelope with cellular membranes, which involves the conserved fusion machinery consisting of gB and the heterodimeric gH/gL complex. The bona fide fusion protein gB depends on the presence of the gH/gL complex for activation. Viral envelope glycoproteins, such as gH, usually contain N-glycans, which can have a strong impact on their folding, transport, and functions. Here, we systematically analyzed the functional relevance of all five predicted N-linked glycosylation sites in the alphaherpesvirus pseudorabies virus (PrV) gH. Despite the fact that mutation of specific sites affected gH transport, in vitro fusion activity, and cell-to-cell spread and resulted in delayed penetration kinetics, even simultaneous inactivation of all five N-glycosylation sites of gH did not severely inhibit formation of infectious virus particles. Thus, our results demonstrate a modulatory but nonessential role of N-glycans for gH function.

UI MeSH Term Description Entries
D008561 Membrane Fusion The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes. Fusion, Membrane,Fusions, Membrane,Membrane Fusions
D011558 Herpesvirus 1, Suid A species of VARICELLOVIRUS producing a respiratory infection (PSEUDORABIES) in swine, its natural host. It also produces an usually fatal ENCEPHALOMYELITIS in cattle, sheep, dogs, cats, foxes, and mink. Aujeszky's Disease Virus,Swine Herpesvirus 1,Aujeszky Disease Virus,Herpesvirus 1 (alpha), Suid,Herpesvirus Suis,Pseudorabies Virus,Suid Herpesvirus 1,Aujeszkys Disease Virus,Herpesvirus 1, Swine,Pseudorabies Viruses,Virus, Pseudorabies,Viruses, Pseudorabies
D011817 Rabbits A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes. Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D002460 Cell Line Established cell cultures that have the potential to propagate indefinitely. Cell Lines,Line, Cell,Lines, Cell
D002462 Cell Membrane The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells. Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D004721 Endoplasmic Reticulum A system of cisternae in the CYTOPLASM of many cells. In places the endoplasmic reticulum is continuous with the plasma membrane (CELL MEMBRANE) or outer membrane of the nuclear envelope. If the outer surfaces of the endoplasmic reticulum membranes are coated with ribosomes, the endoplasmic reticulum is said to be rough-surfaced (ENDOPLASMIC RETICULUM, ROUGH); otherwise it is said to be smooth-surfaced (ENDOPLASMIC RETICULUM, SMOOTH). (King & Stansfield, A Dictionary of Genetics, 4th ed) Ergastoplasm,Reticulum, Endoplasmic
D006031 Glycosylation The synthetic chemistry reaction or enzymatic reaction of adding carbohydrate or glycosyl groups. GLYCOSYLTRANSFERASES carry out the enzymatic glycosylation reactions. The spontaneous, non-enzymatic attachment of reducing sugars to free amino groups in proteins, lipids, or nucleic acids is called GLYCATION (see MAILLARD REACTION). Protein Glycosylation,Glycosylation, Protein
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014759 Viral Envelope Proteins Integral membrane proteins that are incorporated into the VIRAL ENVELOPE. They are glycosylated during VIRAL ASSEMBLY. Envelope Proteins, Viral,Viral Envelope Glycoproteins,Viral Envelope Protein,Virus Envelope Protein,Virus Peplomer Proteins,Bovine Leukemia Virus Glycoprotein gp51,Hepatitis Virus (MHV) Glycoprotein E2,LaCrosse Virus Envelope Glycoprotein G1,Simian Sarcoma Virus Glycoprotein 70,Viral Envelope Glycoprotein gPr90 (Murine Leukemia Virus),Viral Envelope Glycoprotein gp55 (Friend Virus),Viral Envelope Proteins E1,Viral Envelope Proteins E2,Viral Envelope Proteins gp52,Viral Envelope Proteins gp70,Virus Envelope Proteins,Envelope Glycoproteins, Viral,Envelope Protein, Viral,Envelope Protein, Virus,Envelope Proteins, Virus,Glycoproteins, Viral Envelope,Peplomer Proteins, Virus,Protein, Viral Envelope,Protein, Virus Envelope,Proteins, Viral Envelope,Proteins, Virus Envelope,Proteins, Virus Peplomer
D014779 Virus Replication The process of intracellular viral multiplication, consisting of the synthesis of PROTEINS; NUCLEIC ACIDS; and sometimes LIPIDS, and their assembly into a new infectious particle. Viral Replication,Replication, Viral,Replication, Virus,Replications, Viral,Replications, Virus,Viral Replications,Virus Replications

Related Publications

Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
August 1986, Journal of virology,
Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
April 2000, Journal of virology,
Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
January 2021, Pathogens (Basel, Switzerland),
Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
October 1997, Virology,
Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
June 1991, Virology,
Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
January 1999, Glycobiology,
Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
August 2015, PLoS genetics,
Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
December 2020, ACS chemical biology,
Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
June 2005, Journal of virology,
Melina Vallbracht, and Sascha Rehwaldt, and Barbara G Klupp, and Thomas C Mettenleiter, and Walter Fuchs
August 1988, Journal of virology,
Copied contents to your clipboard!