Herpes simplex virus DNA packaging sequences adopt novel structures that are specifically recognized by a component of the cleavage and packaging machinery
K. Adelman et al., Herpes simplex virus DNA packaging sequences adopt novel structures that are specifically recognized by a component of the cleavage and packaging machinery, P NAS US, 98(6), 2001, pp. 3086-3091
Citations number
22
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
The product of the herpes simplex virus type 1 U(L)28 gene is essential for
cleavage of concatemeric viral DNA into genome-length units and packaging
of this DNA into viral procapsids. To address the role of UL28 in this proc
ess, purified U(L)28 protein was assayed for the ability to recognize conse
rved herpesvirus DNA packaging sequences. We report that DNA fragments cont
aining the pac1 DNA packaging motif can be induced by heat treatment to ado
pt novel DNA conformations that migrate faster than the corresponding duple
x in nondenaturing gels, Surprisingly, these novel DNA structures are high-
affinity substrates for UL28 protein binding, whereas double-stranded DNA o
f identical sequence composition is not recognized by U(L)28 protein. We de
monstrate that only one strand of the pad motif is responsible for the form
ation of novel DNA structures that are bound tightly and specifically by UL
28 protein, To determine the relevance of the observed U(L)28 protein-pad i
nteraction to the cleavage and packaging process, we have analyzed the bind
ing affinity of U(L)28 protein for pad mutants previously shown to be defic
ient in cleavage and packaging in vivo. Each of the pac1 mutants exhibited
a decrease in DNA binding by U(L)28 protein that correlated directly with t
he reported reduction in cleavage and packaging efficiency, thereby support
ing a role for the U(L)28 protein-pad interaction in vivo. These data there
fore suggest that the formation of novel DNA structures by the pad motif co
nfers added specificity on recognition of DNA packaging sequences by the U(
L)28-encoded component of the herpesvirus cleavage and packaging machinery.