Effect of cysteine substitutions on dimerization and interfragment linkage of human cytomegalovirus glycoprotein B (gp UL55).
Experiments were carried out to analyze the function of cysteine residues at amino acid positions 506 (cI), 550 (cII), 573 (cIII), and 610 (cIV), in dimerization and/or disulfide linkage of human cytomegalovirus (HCMV) glycoprotein B (gB). Single c-codons or pairs were substituted in the gB sequence of constructs which were used for transfection and selection of stable transfectants. Analysis of gB expression products revealed that single substitutions of cIII or cIV, but neither single nor double substitutions of cI or/and cII prevented gB dimerization. All substituted gB derivatives were, however, no longer processed by proteolytic cleavage. After deletion of the membrane anchor domain, correct proteolytic processing was again observed for anchorless gB forms. Substitutions of cI or cI/cII in secretory gB appeared to interfere with disulfide linkage between gB cleavage fragments. In the case of anchorless gB with substitutions of cII, cIII, or cIII/cIV, however, extracellular gB forms were not recovered. Using the Sindbis expression system recovery of all anchorless gB forms with cysteine substitutions was achieved. Analysis verified involvement of cI/II substitutions in intrachain disulfide linkage between cleavage fragments of HCMV gB.
Eickmann
M
M
Institut für Virologie der Philipps-Universität, Marburg, Germany.
Lange
R
R
Ohlin
M
M
Reschke
M
M
Radsak
K
K
D000595:Amino Acid Sequence; D003545:Cysteine; D003587:Cytomegalovirus / Q000737:chemistry*; D019281:Dimerization; D006801:Humans; D008969:Molecular Sequence Data; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured; D014759:Viral Envelope Proteins / Q000737:chemistry*
D014759:Viral Envelope Proteins; C040495:glycoprotein B, Simplexvirus; D003545:Cysteine