Essential Cations Bound by Avian Sarcoma Virus Integrase

 Home Page National Cancer Institute Macromolecular Crystallography Laboratory Retroviral Integrase Project NCI-Frederick MCL - Protein Structure Section
Structures determined by the Macromolecular Crystallography Laboratory, Protein Structure Section at the NCI-Frederick campus. Work performed in collaboration with the Skalka Laboratory in the Institute for Cancer Research, Fox Chase Cancer Center.








The active site residues of ASV IN, shown in ball-and-stick figures in green (carbon) and red (oxygen) and marked with the one-letter code of the three residue names in blue.

Aspartic acids D64 and D121 and glutamic acid E156 (all negatively charged) were predicted to bind a positively charged metal ion (cation). This prediction proved correct.







2 ASV active sites with Mg and with Mn

This view shows the essential magnesium (Mg, large blue ball) or manganese (Mn, large purple ball) cations and four close coordinating water molecules (smaller balls) bound to the active site of ASV IN. The active site residues are shown as stick figures in the same order as in the image at the top of the page (D64, D121, E156 from left to right). At the bottom center is another structurally important amino acid residue (N153) and a water molecule that help to stabilize the active site, both not shown in the top image.





The electron density map of the metal cation bound to the active site and of the associated water molecules is shown in brown; protein atoms and metal ions are shown in various colors: manganese or magnesium, blue; carbon, green; oxygen, red; water molecules, red spheres.




Click here for information about the interaction between two cations and ASV IN.

The coordinate and image files of ASV IN with bound essential metal cations are available from the PDB.

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contact: Jerry N. Alexandratos at alexandr@ncifcrf.gov.