Integrase
| Integrase Zinc binding domain | |||||||||
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solution structure of the n-terminal zn binding domain of hiv-1 integrase (e form), nmr, 38 structures
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| Identifiers | |||||||||
| Symbol | Integrase_Zn | ||||||||
| Pfam | PF02022 | ||||||||
| InterPro | IPR003308 | ||||||||
| SCOP | 1wjb | ||||||||
| SUPERFAMILY | 1wjb | ||||||||
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| Available protein structures: | |
|---|---|
| Pfam | structures |
| PDB | RCSB PDB; PDBe; PDBj |
| PDBsum | structure summary |
| Integrase core domain | |||||||||
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crystal structure of rsv two-domain integrase
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| Identifiers | |||||||||
| Symbol | rve | ||||||||
| Pfam | PF00665 | ||||||||
| Pfam clan | CL0219 | ||||||||
| InterPro | IPR001584 | ||||||||
| SCOP | 2itg | ||||||||
| SUPERFAMILY | 2itg | ||||||||
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| Available protein structures: | |
|---|---|
| Pfam | structures |
| PDB | RCSB PDB; PDBe; PDBj |
| PDBsum | structure summary |
| Integrase DNA binding domain | |||||||||
|---|---|---|---|---|---|---|---|---|---|
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crystal structure of rsv two-domain integrase
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| Identifiers | |||||||||
| Symbol | IN_DBD_C | ||||||||
| Pfam | PF00552 | ||||||||
| InterPro | IPR001037 | ||||||||
| SCOP | 1ihw | ||||||||
| SUPERFAMILY | 1ihw | ||||||||
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| Available protein structures: | |
|---|---|
| Pfam | structures |
| PDB | RCSB PDB; PDBe; PDBj |
| PDBsum | structure summary |
Retroviral integrase (IN) is an enzyme produced by a retrovirus (such as HIV) that enables its genetic material to be integrated into the DNA of the infected cell. Retroviral INs are not to be confused with phage integrases, such as λ phage integrase (Int) (see site-specific recombination).
IN is a key component in the retroviral pre-integration complex (PIC). The complex of integrase bound to cognate viral DNA (vDNA) ends has been referred to as the intasome.
All retroviral IN proteins contain three canonical domains, connected by flexible linkers:
Crystal and NMR structures of the individual domains and 2-domain constructs of integrases from HIV-1, HIV-2, SIV, and Rous Sarcoma Virus (RSV) have been reported, with the first structures determined in 1994.
Biochemical data and structural data suggest that retroviral IN functions as a tetramer (dimer-of-dimers). All three domains are important for multimerisation and viral DNA binding. Early in 2010, scientists solved the crystal structure of IN from prototype foamy virus (PFV) assembled on viral DNA ends.
In addition, several host cellular proteins have been shown to interact with IN to facilitate the integration process. Human chromatin-associated protein LEDGF, which tightly binds HIV IN and directs HIV PIC towards highly expressed genes for integration, is an example of such a host factor.
Integration occurs following production of the double-stranded viral DNA by the viral RNA/DNA-dependent DNA polymerase reverse transcriptase.
The main function of IN is to insert the viral DNA into the host chromosomal DNA, a step that is essential for HIV replication. Integration is a point of no return for the cell, which becomes a permanent carrier of the viral genome (provirus). Integration is in part responsible for the persistence of retroviral infections. After integration, the viral gene expression and particle production may take place immediately or at some point in the future. The timing, it is presumed, depends on the activity of the chromosomal locus hosting the provirus.
Retroviral IN catalyzes two reactions:
Both reactions are catalysed by the same active site and occur via transesterification, without a covalent protein-DNA intermediate, in contrast to reactions catalysed by Ser and Tyr recombinases (see site specific recombination).
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Wikipedia