Sandbox Reserved 958: Difference between revisions
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The 3'-processing is a reaction where the integrase and most precisely, the catalytic core by association with the N-ter domain catalyze the '''excision of two 3'-terminal nucleotides''' on both strands of the DNA due to a nucleophilic attack using water. Indeed it is a specific cleavage where two nucleotides on the 3' viral DNA extremities are excised, after that the two newly 3'-OH are used for a second reaction : the strand transfer. To make it possible, integrase needs Mg++ or Mn++ and also zinc ions. Moreover dimers of IN are formed to induce this reaction, then these two dimers are linked on the viral DNA extremities to form a tetramer of IN<ref name="Carayon">PMID:20164093</ref>. The 3' processing reaction occurs before the PIC penetration in the nucleus. | The 3'-processing is a reaction where the integrase and most precisely, the catalytic core by association with the N-ter domain catalyze the '''excision of two 3'-terminal nucleotides''' on both strands of the DNA due to a nucleophilic attack using water. Indeed it is a specific cleavage where two nucleotides on the 3' viral DNA extremities are excised, after that the two newly 3'-OH are used for a second reaction : the strand transfer. To make it possible, integrase needs Mg++ or Mn++ and also zinc ions. Moreover dimers of IN are formed to induce this reaction, then these two dimers are linked on the viral DNA extremities to form a tetramer of IN<ref name="Carayon">PMID:20164093</ref>. The 3' processing reaction occurs before the PIC penetration in the nucleus. | ||
===Strand Transfer=== | ===Strand Transfer=== | ||
The strand transfer is the really integration step, it provokes the integration of the viral DNA into the host genome by two sequential transesterifications. The integration site is a palindromic and symmetric sequence composed of five nucleotides. This sequence is cleaved to allow the fusion of the LTR extremities of the viral DNA. Afterwards two 3' nucleotides are excised and the joining strand of the five nucleotides is full-filed<ref name="Mbisa">PMID:21694910</ref>. The structure that permits this transfer is the intasome (viral DNA + integrase) by association with the '''Lens Epithelium-derived Growth factor (LEDGF)''' and the '''p75''' protein that has a cofactor activity for | The strand transfer is the really integration step, it provokes the integration of the viral DNA into the host genome by two sequential transesterifications. The integration site is a palindromic and symmetric sequence composed of five nucleotides. This sequence is cleaved to allow the fusion of the LTR extremities of the viral DNA. Afterwards two 3' nucleotides are excised and the joining strand of the five nucleotides is full-filed<ref name="Mbisa">PMID:21694910</ref>. The structure that permits this transfer is the intasome (viral DNA + integrase) by association with the '''Lens Epithelium-derived Growth factor (LEDGF)''' and the '''p75''' protein that has a cofactor activity for integrase and is a tethering site for chromatin binding. | ||
[[Image:3108751 idr-4-065f1.png]] | [[Image:3108751 idr-4-065f1.png]] | ||