title: Mechanism of action of ribonuclease H isolated from avian myeloblastosis virus and Escherichia coli.
abstract: 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: D001354:Avian Leukosis Virus / Q000201:enzymology*; D004720:Endonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D005092:Exonucleases / Q000378:metabolism; D010759:Phosphorus Isotopes; D011119:Polynucleotides / Q000378:metabolism; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D012260:Ribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D014316:Tritium
chemical_list: D010759:Phosphorus Isotopes; D011119:Polynucleotides; D014316:Tritium; D012194:RNA-Directed DNA Polymerase; D004720:Endonucleases; D005092:Exonucleases; D012260:Ribonucleases