EC Number   |
General Information |
Reference |
|---|
   3.1.13.2 | evolution |
RNase H belongs to the eukaryotic Mre11/Rad50 (MR) and bacterial SbcCD complex family. The crystal structure of T4 RNase H shows a close homology to flap endonucleases of the FEN-1 family rather than RNase H family. FEN-1 is a family of structure-specific 5'-nucleases, which is conserved from bacteriophage to humans |
751635 |
| 3.1.13.2 | evolution |
RNaseH enzymes belong to the nucleotidyl transferase superfamily whose members share a similar protein fold and catalytic mechanism |
749598 |
| 3.1.13.2 | malfunction |
inhibition of hepatitis B virus (HBV) replication by N-hydroxyisoquinolinedione and N-hydroxypyridinedione ribonuclease H inhibitors. Blocking the HBV RNaseH activity prevents removal of the RNA strand from the minus-polarity DNA strand, resulting in an accumulation of RNA:DNA heteroduplexes |
749600 |
| 3.1.13.2 | malfunction |
the V43I substitution increases the ratio between exonuclease (EC 3.1.13.2) and endonuclease (EC 3.1.99.) activities of RNase H whereas L242I substitution does not affect the nuclease activity of RNase H in vitro. The Das13 mutant of RNase H has substitutions of valine 43 and leucine 242 with isoleucines. Both mutations are necessary for the full das mutant effect in vivo. The V43I substitution may lead to disposition of H4 helix, responsible for the interaction with the first base pairs of 5' end of branched DNA. These structural changes may affect unwinding of the first base pairs of gapped or nicked DNA generating a short flap and therefore may stabilize the DNA-enzyme complex. The L242I substitution does not affect the structure of RNase H and its role in providing the das-effect remains unclear |
751635 |
| 3.1.13.2 | more |
HSV-1 Pol contains four domains: the pre-NH2-terminal domain, the NH2-terminal domain, the 3'-to-5' exonuclease (Exo) domain, and the polymerase domain, composed of the palm, finger, and thumb subdomains |
751429 |
| 3.1.13.2 | more |
molecular modelling of the nuclease structure |
751635 |
| 3.1.13.2 | more |
the RNaseH active site contains four conserved carboxylates (the DEDD motif) that coordinate two divalent cations, usually Mg2+. The RNA cleavage mechanism requires both cations to promote a hydroxyl-mediated nucleophilic scission reaction |
749598 |
| 3.1.13.2 | physiological function |
among the activities of herpes simplex virus 1 DNA polymerase (HSV-1 Pol) is an intrinsic RNase H activity that cleaves RNA from RNA-DNA hybrids. The wild-type HSV-1 Pol is able to cleave RNA from the annealed RNA-DNA hairpin template, but only detectably with a 3' RNA terminus in a 3'-to-5' direction and at a rate lower than that of the exonuclease activity. These results suggest that HSV-1 Pol does not have an RNase H separable from its 3'-to-5' exonuclease activity and that this activity prefers DNA degradation over degradation of RNA from RNA-DNA hybrids. No RNase H activity of HSV-1 DNA polymerase on RNA-DNA hybrids with 5' RNA termini |
751429 |
| 3.1.13.2 | physiological function |
RNase H is a 5'-nuclease required to remove RNA primers from lagging strand fragments during DNA replication. It forms the gp46/47 enzyme complex consisting of a DNA-activated ATPase, an ssDNA endonuclease and a 3'-5' dsDNA exonuclease |
751635 |
| 3.1.13.2 | physiological function |
the endonucleolytic RNaseH activity (EC 3.1.26.4) requires an DNA:RNA duplex 14 nt or more and cannot tolerate a stem-loop in either the RNA or DNA strands. It tolerates a nick in the DNA strand but not a gap. The RNaseH has no obvious sequence specificity or positional dependence within the RNA, and it cuts the RNA at multiple positions even within the minimal 14 nt duplex. The RNaseH also possesses a processive 3'-5' exoribonuclease activity (EC 3.1.13.2) that is slower than the endonucleolytic reaction. The HBV reverse transcription mechanism features an initial endoribonucleolytic cut, 3'-5' degradation of RNA, and a sequence-independent terminal RNA cleavage |
749598 |
