A particular DNA structure is required for the function of a cis-acting component of the Epstein-Barr virus OriLyt origin of replication

Nucleic Acids Res. 1997 Apr 1;25(7):1347-54. doi: 10.1093/nar/25.7.1347.


OriLyt, thecis-acting element of Epstein-Barr virus lytic origin of replication, consists of upstream and downstream components. The upstream component plays a dual role in transcription and replication. The downstream component contains a homopurine-homopyrimidine sequence which forms an H palindrome. We show that the downstream component can adopt a triple helix structure in vitro, that the 5' border of the homopyrimidine sequence is sensitive to P1 nuclease when carried by a supercoiled plasmid and that an oligonucleotide complementary to the homopyrimidine strand is taken up by a plasmid carrying the OriLyt H palindrome. We also show that all mutations which alter the H palindrome impair both oligonucleotide uptake and OriLyt-dependent replication. Interestingly, compensatory mutations which restore an H palindrome also restore oligonucleotide uptake by the mutated plasmids and their OriLyt-dependent replication. Thus, there is a strong correlation between the inability of the OriLyt H palindrome to form a non-B-DNA structure in vitro and impairment of OriLyt-dependent replication. This suggests that the presence of a non-B-DNA structure in the OriLyt downstream component is required for OriLyt-dependent replication.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • DNA Replication
  • DNA, Superhelical / metabolism
  • DNA, Viral / chemistry*
  • DNA, Viral / physiology
  • Herpesvirus 4, Human / genetics*
  • Herpesvirus 4, Human / physiology
  • Humans
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Nucleic Acid Conformation*
  • Replication Origin*
  • Single-Strand Specific DNA and RNA Endonucleases / metabolism
  • Structure-Activity Relationship
  • Tumor Cells, Cultured
  • Virus Replication*


  • DNA, Superhelical
  • DNA, Viral
  • Single-Strand Specific DNA and RNA Endonucleases