Endocytosis of Varicella-Zoster Virus Glycoproteins: Virion Envelopment and Egress
Charles Grose, Lucie Maresova, Guruprasad Medigeshi, Gregory K. Scott, and Gary Thomas
from: Alpha Herpesviruses: Molecular and Cellular Biology (Edited by: R. M. Sandri-Goldin). Caister Academic Press, U.K. (2006)
Endocytosis from the infected cell surface is a property of the four major glycoproteins of varicella-zoster virus (VZV), designated gE, gI, gB and gH. Each of these glycoproteins has a functional endocytosis motif in its cytoplasmic tail. Three have tyrosine based motifs, while gI has a dileucine motif. The YAGL motif of gE is located adjacent to an acidic cluster, which also contains serine and threonine residues variably phosphorylated by both a viral kinase (ORF 47 kinase) and casein kinase II. The acidic cluster interacts with a connector protein called prosphofurin acidic cluster sorting protein 1 (PACS-1) after clathrin mediated internalization. Although the function of endocytosis has been elusive, recent research suggests that the internalized VZV glycoproteins traffic to the site of virion assembly in the trans-Golgi network and are subsequently incorporated into the envelopes of nascent virions. In turn, the enveloped virions reside within vacuoles, which travel toward and fuse with the plasma membrane. A recombinant VZV genome containing a gE gene lacking only its endocytosis motif cannot replicate. Taken together, the above results indicate the importance of VZV glycoprotein endocytosis in the life cycle of this alpha herpesvirus read more ...