Cellular DNA ligase I is recruited to cytoplasmic vaccinia virus factories and masks the role of the vaccinia ligase in viral DNA replication.
Vaccinia virus (VACV) encodes DNA polymerase and additional proteins that enable cytoplasmic replication. We confirmed the ability of VACV DNA ligase mutants to replicate and tested the hypothesis that cellular ligases compensate for loss of viral gene expression. RNA silencing of human DNA ligase I expression and a small molecule inhibitor of human DNA ligase I [corrected] severely reduced replication of viral DNA in cells infected with VACV ligase-deficient mutants, indicating that the cellular enzyme plays a complementary role. Replication of ligase-deficient VACV was greatly reduced and delayed in resting primary cells, correlating with initial low levels of ligase I and subsequent viral induction and localization of ligase I in virus factories. These studies indicate that DNA ligation is essential for poxvirus replication and explain the ability of ligase deletion mutants to replicate in dividing cells but exhibit decreased pathogenicity in mice. Encoding its own ligase might allow VACV to "jump-start" DNA synthesis.
Paran
Nir
N
Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
De Silva
Frank S
FS
Senkevich
Tatiana G
TG
Moss
Bernard
B
D000818:Animals; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D014615:Vaccinia / Q000201:enzymology* / Q000235:genetics / Q000821:virology; D014616:Vaccinia virus / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
C000607892:LIG1 protein, human; D014764:Viral Proteins; D011088:DNA Ligases; D000072481:DNA Ligase ATP