Mechanism of action of ribonuclease H isolated from avian myeloblastosis virus and Escherichia coli

Proc Natl Acad Sci U S A. 1973 Feb;70(2):466-70. doi: 10.1073/pnas.70.2.466.


Purified preparations of RNA-dependent DNA polymerase isolated from avain myeloblastosis virus contain RNase H activity. Labeled ribohomopolymers are degraded in the presence of their complementary deoxyribopolymer, except [(3)H]poly(U).poly(dA). The degradation products formed from [(3)H]poly(A).poly(dT) were identified as oligonucleotides containing 3'-hydroxyl and 5'-phosphate termini, while AMP was not detected. The nuclease has been characterized as a processive exonuclease that requires ends of poly(A) chains for activity. Exonucleolytic attack occurs in both 5' to 3' and 3' to 5' directions.RNase H has also been purified from E. coli. This nuclease degrades all homoribopolymers tested in the presence of their complementary deoxyribopolymers to yield oligonucleotides with 5'-phosphate and 3'-hydroxyl termini. E. coli RNase H has been characterized as an endonuclease.

MeSH terms

  • Avian Leukosis Virus / enzymology*
  • Endonucleases / metabolism
  • Escherichia coli / enzymology*
  • Exonucleases / metabolism
  • Phosphorus Isotopes
  • Polynucleotides / metabolism
  • RNA-Directed DNA Polymerase / metabolism
  • Ribonucleases / isolation & purification
  • Ribonucleases / metabolism*
  • Tritium


  • Phosphorus Isotopes
  • Polynucleotides
  • Tritium
  • RNA-Directed DNA Polymerase
  • Endonucleases
  • Exonucleases
  • Ribonucleases