Download The UL21 gene of herpes simplex virus 1

Oral Presentation
Jacob Marsh
Genetics Program
Department of Microbiology and Immunology
Dr. John Wills
Packaging Requirements for the UL21 Tegument Protein of Herpes
Simplex Virus
Jacob A. Marsh, Amy L. Harper, Nicholas L. Baird, David G. Meckes, Pei-Chun Yeh, John W.
Wills
The UL21 gene of herpes simplex virus (HSV) encodes a 535-amino-acid tegument protein that
is located throughout the cytoplasm and nuclei of infected cells. Little is known of the function
of this protein, but studies of pseudorabies virus (PRV) suggest a role in viral DNA processing in
the nucleus (J Virol. 66:7096-103, Vet Res. 32:47-54). It has also been suggested that UL21
from HSV may be associated with microtubules (Genes Cells. 6:955-66). Mutants that lack this
gene exhibit slow plaque formation and a ten-fold reduction in virus titer. In PRV, UL21 forms a
complex with UL16, another tegument protein. In this study, we confirmed this interaction in
HSV-1 by using immunopreciptation and GST pull-down assays. In addition, we determined that
the C-terminal half of UL21 is both necessary and sufficient for the UL21-UL16 interaction.
Using a transfection/infection-based assay, we found this same half of UL21 is necessary and
sufficient for packaging into the virion, both in the presence and absence of full-length UL21.
Analysis of knock-out mutants of each protein revealed that the interaction of UL21 and UL16 is
not required for the packaging of either protein into the virion. Taken together, these data
indicate that the C-terminal domain of UL21 is responsible for binding to both UL16 and some
other protein needed for association with capsids and subsequently for packaging into the virion.
Herpes simplex virus, tegument, assembly, egress, protein-protein interaction
National Institute of Health, National Heart Association