Sandbox Reserved 712: Difference between revisions

<scene name='Sandbox_Reserved_712/3ggu/1'>3ggu</scene> is a drug resistant HIV protease. Shown is a patient's variant in complex with [[darunavir]].

[[HIV-1 protease]] (PR) are essential for the functioning of the retrovirus that causes AIDS. HIV needs active proteases to process [[Hiv-1 gag]] & gap - polymerase polyprotein precursors into mature structural proteins and replicative enzymes.  

HIV proteases contain a highly conserved region Asp - Thr - Gly (<scene name='Sandbox_Reserved_712/Activesiteasp25/1'>Asp25</scene>, <scene name='Sandbox_Reserved_712/Activesitethr26/1'>Thr26</scene> and  

Because of its importance for the life-cycle of the retrovirus, HIV-PRs are the major target for anti-HIV treatment.  

3ggu (also PR_DRV5) is a mutated clinically derived PR that shows phenotypical resistance to darunavir. Darunavir is a human immunodeficiency virus (HIV) protease (PR) inhibitor (PI) which has inhibiting effects on many HIV type 1 PR variants that show resistance to earlier-generation-PIs. <ref name="Molecular"> PMID:19535439 </ref>

Darunavir (also known as TMC114) is a HIV-PR Inhibitor ([[Molecular Playground/HIV Protease Inhibitor]]). The wild-type HIV as well as a large penal of PI-resistant recombinant viruses derived from clinical samples show high susceptibility to darunavir. <ref> PMID:15917527 </ref>

One reason for the high potency of darunavir is the strong binding of the PI to the main-chains of the protease active-site amino acids. <ref> PMID:14506019 </ref> A second reason might be the ability of the PI to fit closely into the substrate envelope. <ref>PMID:15479840</ref>

Darunavir shows a high genetical barrier to resistance development. In fact studies indicate that the development of resistance needs more specific mutations and develops more slowly. <ref> PMID:15917527 </ref>

Darunavir resistance-associated mutations are V11I, V32I, <scene name='Sandbox_Reserved_712/L33f/1'>L33F</scene>, I47V, I50V, I54L, I54M, G73S, L76V, <scene name='Sandbox_Reserved_712/I84v/2'>I84V</scene> and  

The <scene name='Sandbox_Reserved_712/Activesite/2'>active site</scene> is located in the tunnel. The <scene name='Sandbox_Reserved_712/Activesite/2'>active site</scene> uses water molecules to break the subrate-protein chain. It's most important residues are two aspartate amino acids.

 

(Inhibitors occupie similar positions like the natural substrate-protein chain.)

[[Image:Positions_of_the_mutations_in_PR_variants_used_for_structural_studies.jpg|left|320px|thumb| Fig.2 Positions of the mutations in PR variants used for structural studies. <ref name="Molecular" />]]

[[Image: Structural_changes_in_PRdrv5_mutant.jpg|right|200px|thumb| Fig.3 Structural changes in PR_DRV5 mutant relative to wild-type PR. <ref name="Molecular" />]]

[[Image: Detailed_view_of_darunavir-enzyme_interactions.jpg|right|200px|thumb| Fig.4 Detailed view of the darunavir-enzyme interactions. <ref name="Molecular" />]]

The crystal structure was determined in complex with darunavir with 1.8-Å resolutions. The crystal is formed out of one PR dimer in the asymmetric unit with two inhibitor molecules bound in alternative orientations.

<scene name='Sandbox_Reserved_712/I84v/2'>I84V</scene> (see Fig.2, Part B, indicated in bold print) that are directly involved in substrate-darunavir-interactions (change of S2/S2' subsites).

The pictures on the right (Fig.3 and Fig.4) show the regions (indicated in blue) that undergo structural changes caused by the mutations.

The high mutation rate of the virus leads to the fast development of drug resistance. The phenotypic characterization, enzyme kinetics and X-ray structural analysis of recombinant viruses offers a way to get a better understanding of the drug resistance. The knowledge we gain through that kind of experiments could help in the future to develop new drugs for HIV-positive patients.