Rous Sarcoma Virus: Structural Basis For Specificity Of Retroviral Proteases

At present a wire frame image of the structure of the proteins is shown

The molecule can be rotated at any time by left clicking the mouse on the molecule and dragging the mouse with the left button depressed. Or you can switch on rotation using the buttons below.

Using the buttons below, first change the peptide substrates to space fill so see how they are located at the active site of the enzyme. Now change the aspartate residues in the four chains of the enzyme to space fill to see how they interact with the substrate. This retroviral protease is an aspartyl protease; this means that aspartate amino acids participate in the catalytic reaction.  You will see that each chain of the protease contains four aspartates. Three of these are at the active site and take part in the cleavage of the peptide.

Using the buttons below, change each of the chains to ribbons or space-fill to see, more clearly, how the four chains of the protease interact with the peptides to be cleaved. Note that each active site of the enzyme is formed by two protein chains that interact with the peptide. 

The crystal structure shows RSV S9 protease with the inhibitor, Arg-Val-Leu-r-Phe-Glu-Ala-Nle-NH2, a reduced peptide analogue of the HIV-1 CA-p2 cleavage site. Interactions of RSV S9 protease with the CA-p2 analogue are very similar to those observed in the crystal structure of HIV-1 protease with the same inhibitor. 

The red molecules are water

To return to the original wire-frame structure, use the reload/refresh button on your browser.

Further changes and selection may be made using the Chime menu. Right click on the molecule to show the Chime menu.

© Richard Hunt, University of South Carolina School of Medicine