Cross talk among the glycoproteins involved in herpes simplex virus entry and fusion: the interaction between gB and gH/gL does not necessarily require gD.
The gD, gB, and gH/gL glycoprotein quartet constitutes the basic apparatus for herpes simplex virus (HSV) entry into the cell and fusion. gD serves as a receptor binding glycoprotein and trigger of fusion. The conserved gB and gH/gL execute fusion. Central to understanding HSV entry/fusion has become the dissection of how the four glycoproteins engage in cross talk. While the independent interactions of gD with gB and gD with gH/gL have been documented, less is known of the interaction of gB with gH/gL. So far, this interaction has been detected only in the presence of gD by means of a split green fluorescent protein complementation assay. Here, we show that gB interacts with gH/gL in the absence of gD. The gB-gH/gL complex was best detected with a form of gB in which the endocytosis and phosphorylation motif have been deleted; this form of gB persists in the membranes of the exocytic pathway and is not endocytosed. The gB-gH/gL interaction was detected both in whole transfected cells by means of a split yellow fluorescent protein complementation assay and, biochemically, by a pull-down assay. Results with a panel of chimeric forms of gB, in which portions of the glycoprotein bracketed by consecutive cysteines were replaced with the corresponding portions from human herpesvirus 8 gB, favor the view that gB carries multiple sites for interaction with gH/gL, and one of these sites is located in the pleckstrin-like domain 1 carrying the bipartite fusion loop.
Avitabile
Elisa
E
Department of Experimental Pathology, Section on Microbiology and Virology, Alma Mater Studiorum-University of Bologna, Via San Giacomo 12, 40126 Bologna, Italy.
Forghieri
Cristina
C
Campadelli-Fiume
Gabriella
G
D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008561:Membrane Fusion; D018139:Simplexvirus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity / Q000502:physiology; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D053586:Virus Internalization
D006023:Glycoproteins; D014759:Viral Envelope Proteins; C040495:glycoprotein B, Simplexvirus; C039447:glycoprotein D, Human herpesvirus 1; C044200:glycoprotein H, herpes simplex virus type 1; C077407:glycoprotein L, Human herpesvirus 1