Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1996 Feb;70(2):794-800.
doi: 10.1128/JVI.70.2.794-800.1996.

Vaccinia virion protein I8R has both DNA and RNA helicase activities: implications for vaccinia virus transcription

C D Bayliss  1 , G L Smith
Affiliations

Vaccinia virion protein I8R has both DNA and RNA helicase activities: implications for vaccinia virus transcription

C D Bayliss et al. J Virol. 1996 Feb.

Abstract

A nucleic acid-dependent ATPase was purified from vaccinia virions and shown to have both DNA:DNA and RNA:RNA helicase activities. This is only the third helicase to be identified that can unwind both DNA and RNA duplexes. The DNA helicase activity copurified with nucleoside triphosphate phosphohydrolase II (NPHII), an RNA helicase encoded by gene I8R (S. Shuman, Proc. Natl. Acad. Sci. USA 89:10935-10939, 1992). Immunodepletion with two antisera to NPHII and analysis of recombinant NPHII protein (C. H. Gross and S. Shuman, J. Virol. 69:4727-4736, 1995) confirmed that the DNA helicase activity was encoded by the I8R gene. The I8R DNA helicase unwound DNA in a 3'-to-5' direction only, unwound duplexes of 35 bp but not 45 bp, and could be stimulated to unwind longer duplexes by the Escherichia coli single-stranded DNA-binding protein. DNA helicase activity was not stimulated by salt and was sensitive to 100 mM NaCl or KCl. The I8R protein has amino acid similarity to human RNA helicase A and to nuclear DNA helicase II, a bovine DNA and RNA helicase. On the basis of the phenotype of I8R temperature-sensitive mutants, it was suggested that the I8R protein is not required for DNA replication but might aid in the extrusion of early mRNA from the virus core. The DNA helicase activity of the I8R protein allows another interpretation of the mutant phenotype, namely, that the I8R DNA helicase activity is required for initiation of early transcription from within vaccinia virions.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. J Biol Chem. 1993 Jun 5;268(16):11798-802 - PubMed
    1. Proc Natl Acad Sci U S A. 1993 Jun 1;90(11):5086-90 - PubMed
    1. J Biol Chem. 1993 Sep 25;268(27):20016-21 - PubMed
    1. Nucleic Acids Res. 1993 Nov 11;21(22):5251-5 - PubMed
    1. J Biol Chem. 1994 Feb 4;269(5):3283-9 - PubMed

Publication types

MeSH terms

LinkOut - more resources