Hepatitis delta virus ribozyme
The hepatitis delta virus (HDV) ribozyme is a non-coding RNA found in the hepatitis delta virus that is necessary for viral replication and is the only known human virus that utilizes ribozyme activity to infect its host. The ribozyme acts to process the RNA transcripts to unit lengths in a self-cleavage reaction during replication of the hepatitis delta virus, which is thought to propagate by a double rolling circle mechanism. The ribozyme is active in vivo in the absence of any protein factors and was the fastest known naturally occurring self-cleaving RNA at the time of its discovery.
| Hepatitis delta virus ribozyme | |
|---|---|
Predicted secondary structure and sequence conservation of HDV ribozyme | |
| Identifiers | |
| Symbol | HDV_ribozyme |
| Rfam | RF00094 |
| Other data | |
| RNA type | Gene; ribozyme |
| Domain(s) | Viruses |
| SO | SO:0000374 |
| PDB structures | PDBe |
The crystal structure of this ribozyme has been solved using X-ray crystallography and shows five helical segments connected by a double pseudoknot.
In addition to the sense (genomic version), all HDV viruses also have an antigenomic version of the HDV ribozyme. This version is not the exact complementary sequence but adopts the same structure as the sense (genomic) strand. The only "significant" differences between the two are a small bulge in P4 stem and a shorter J4/2 junction. Both the genomic and antigenomic ribozymes are necessary for replication.