InterPro domain: IPR022898

Ribonuclease HII is involved in the degradation of the ribonucleotide moiety on RNA-DNA hybrid molecules carrying out endonucleolytic cleavage to 5'-phospo-monoester [ 1 , 2 ]. This entry is specific for ribonuclease HII. Several bacteria, such as Bacillus subtilis, have two different type II RNases H, RNases HII and HIII [ 3 ]; double deletion of these leads to cellular lethality. It appears that type I and type II RNases H also have overlapping functions in cells, as over-expression of Escherichia coli RNase HII can complement an RNase HI deletion phenotype [ 4 ]. In Leishmania mitochondria, of the four distinct RNase H genes (H1, HIIA, HIIB, HIIC), HIIC is essential for the survival of the parasite and thus can be a potential target for anti-leishmanial chemotherapy [ 5 ]. Ribonuclease H (RNase H) is classified into two families, type I (prokaryotic RNase HI, eukaryotic RNase H1 and viral RNase H) and type II (prokaryotic RNase HII and HIII, and eukaryotic RNase H2). RNase H endonucleolytically hydrolyzes an RNA strand when it is annealed to a complementary DNA strand in the presence of divalent cations, in DNA replication and repair [ 6 ].

1. Crystal structures of RNase H2 in complex with nucleic acid reveal the mechanism of RNA-DNA junction recognition and cleavage. Mol. Cell 40, 658-70
2. Structural biochemistry of a type 2 RNase H: RNA primer recognition and removal during DNA replication. J. Mol. Biol. 307, 541-56
3. Comparative sequence analysis of ribonucleases HII, III, II PH and D. Nucleic Acids Res. 25, 3187-95
4. Biochemical characterization and functional complementation of ribonuclease HII and ribonuclease HIII from Chlamydophila pneumoniae AR39. Microbiology (Reading, Engl.) 153, 787-93
5. A type II ribonuclease H from Leishmania mitochondria: an enzyme essential for the growth of the parasite. Mol. Biochem. Parasitol. 143, 135-45
6. Ribonuclease H. FEBS J. 276, 1481