title: DNA binding and condensation properties of the herpes simplex virus type 1 triplex protein VP19C.
abstract: Herpesvirus capsids are regular icosahedrons with a diameter of a 125 nm and are made up of 162 capsomeres arranged on a T = 16 lattice. The capsomeres (VP5) interact with the triplex structure, which is a unique structural feature of herpesvirus capsid shells. The triplex is a heterotrimeric complex; one molecule of VP19C and two of VP23 form a three-pronged structure that acts to stabilize the capsid shell through interactions with adjacent capsomeres. VP19C interacts with VP23 and with the major capsid protein VP5 and is required for the nuclear localization of VP23. Mutation of VP19C results in the abrogation of capsid shell synthesis. Analysis of the sequence of VP19C showed the N-terminus of VP19C is very basic and glycine rich. It was hypothesized that this domain could potentially bind to DNA. In this study an electrophoretic mobility shift assay (EMSA) and a DNA condensation assay were performed to demonstrate that VP19C can bind DNA. Purified VP19C was able to bind to both a DNA fragment of HSV-1 origin as well as a bacterial plasmid sequence indicating that this activity is non-specific. Ultra-structural imaging of the nucleo-protein complexes revealed that VP19C condensed the DNA and forms toroidal DNA structures. Both the DNA binding and condensing properties of VP19C were mapped to the N-terminal 72 amino acids of the protein. Mutational studies revealed that the positively charged arginine residues in this N-terminal domain are required for this binding. This DNA binding activity, which resides in a non-conserved region of the protein could be required for stabilization of HSV-1 DNA association in the capsid shell.
authors.affiliation: Viral Oncology Program, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Alakesh
authors.initials: A
authors.lastname: Bera
authors.affiliation: Department of Biology and Integrated Imaging Center, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Edward M
authors.initials: EM
authors.lastname: Perkins
authors.affiliation: HiT Center and Department of Pharmacology and Molecular Sciences, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhu
authors.affiliation: HiT Center and Department of Pharmacology and Molecular Sciences, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Heng
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Viral Oncology Program, The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Johns Hopkins University, Baltimore, Maryland, United States of America.
authors.forename: Prashant
authors.initials: P
authors.lastname: Desai
mesh_terms: D001120:Arginine / Q000378:metabolism; D002213:Capsid / Q000378:metabolism; D036022:Capsid Proteins / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism; D018259:Herpesvirus 1, Human / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020539:Sequence Analysis, Protein / Q000379:methods
chemical_list: D036022:Capsid Proteins; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C082563:VP19 protein, Human herpesvirus 1; D001120:Arginine; D005998:Glycine