Antigenic domain 1 is required for oligomerization of human cytomegalovirus glycoprotein B.
Human cytomegalovirus (HCMV) glycoprotein B (gB) is an abundant virion envelope protein that has been shown to be essential for the infectivity of HCMV. HCMV gB is also one of the most immunogenic virus-encoded proteins, and a significant fraction of virus neutralizing antibodies are directed at gB. A linear domain of gB designated AD-1 (antigenic domain 1) represents a dominant antibody binding site on this protein. AD-1 from clinical isolates of HCMV exhibits little sequence variation, suggesting that AD-1 plays an essential role in gB structure or function. We investigated this possibility by examining the role of AD-1 in early steps of gB synthesis. Our results from studies using eukaryotic cells indicated that amino acid (aa) 635 of the gB sequence represented the carboxyl-terminal limit of this domain and that deletion of aa 560 to 640 of the gB sequence resulted in loss of AD-1 expression. AD-1 was shown to be required for oligomerization of gB. Mutation of cysteine at either position 573 or 610 in AD-1 resulted in loss of its reactivity with AD-1-specific monoclonal antibodies and gB oligomerization. Infectious virus could not be recovered from HCMV bacterial artificial chromosomes following introduction of these mutations into the HCMV genome, suggesting that AD-1 was an essential structural domain required for gB function in the replicative cycle of HCMV. Sequence alignment of AD-1 with homologous regions of gBs from other herpesviruses demonstrated significant relatedness, raising the possibility that this domain may contribute to multimerization of gBs in other herpesviruses.
Britt
William J
WJ
Department of Pediatrics, University of Alabama School of Medicine, Birmingham, AL 35294, USA. wbritt@peds.uab.edu
Jarvis
Michael A
MA
Drummond
Derek D
DD
Mach
Michael
M
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017124:Conserved Sequence; D003587:Cytomegalovirus / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D014759:Viral Envelope Proteins; C040495:glycoprotein B, Simplexvirus