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Structural basis for specificity of retroviral proteases
1Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107,
Biochemistry
|April 29, 1998
Summary
Engineered Rous sarcoma virus (RSV) protease S9 variant shows high affinity for HIV-1 protease targets. Structural analysis reveals key differences in flap residues, verifying molecular basis for protease specificity.
Area of Science:
- Biochemistry
- Structural Biology
- Virology
Background:
- Rous sarcoma virus (RSV) and Human Immunodeficiency Virus type 1 (HIV-1) are retroviruses with distinct proteases.
- Understanding protease specificity is crucial for developing antiviral therapies.
Purpose of the Study:
- To engineer an RSV protease variant (S9) with enhanced affinity for HIV-1 protease substrates and inhibitors.
- To elucidate the structural basis for specificity differences between RSV and HIV-1 proteases.
Main Methods:
- Site-directed mutagenesis to create the RSV S9 protease variant with 9 substitutions.
- X-ray crystallography to determine the structure of RSV S9 protease complexed with an HIV-1 CA-p2 cleavage site analogue inhibitor.
- Mutational analysis to assess the role of specific residues in catalytic activity.
Main Results:
- The RSV S9 variant effectively hydrolyzes HIV-1 protease substrates.
- Crystal structure reveals unique loop residues (61-63) at the base of the flaps, essential for activity.
- Flap residue interactions with the inhibitor mimic those seen in HIV-1 protease complexes.
Conclusions:
- The study provides the first crystal structure of an avian retroviral protease with an inhibitor.
- Structural and mutational data verify the molecular basis for specificity differences between RSV and HIV-1 proteases.
- RSV S9 protease serves as a valuable tool for studying protease structure-function relationships.