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Structure of an inhibitor complex of the proteinase from feline immunodeficiency virus
A Wlodawer1, A Gustchina, L Reshetnikova
1Macromolecular Structure Laboratory, NCI-Frederick Cancer Research and Development Center, Maryland 21702, USA.
Abstract:
The crystal structure of a recombinant form of the proteinase encoded by the feline immunodeficiency virus (FIV PR) has been solved at 2 A resolution and refined to an R-factor of 0.148. The refined structure includes a peptidomimetic, statine-based inhibitor, LP-149, which is an even more potent inhibitor of HIV PR. Kinetic parameters were obtained for the cleavage of five substrates by FIV PR, and inhibition constants were measured for four inhibitors. The structure of FIV PR resembles other related retroviral enzymes although few inhibitors of HIV PR are capable of inhibiting FIV PR. The structure of FIV PR will enhance our knowledge of this class of enzymes, and will direct testing of new proteinase inhibitors in a feline animal model.
Insights
The feline immunodeficiency virus proteinase (FIV PR) crystal structure was determined, revealing insights into enzyme function. This research aids in developing targeted proteinase inhibitors for feline models.
Area of Science:
- Structural Biology
- Virology
- Biochemistry
Background:
- Feline immunodeficiency virus (FIV) is an important pathogen in cats.
- Understanding the FIV proteinase (FIV PR) is crucial for developing antiviral therapies.
- Retroviral proteinases share structural similarities but exhibit distinct inhibitor profiles.
Purpose of the Study:
- To determine the high-resolution crystal structure of FIV PR.
- To characterize the enzymatic activity and inhibition of FIV PR.
- To provide a structural basis for designing novel FIV PR inhibitors.
Main Methods:
- X-ray crystallography to solve the FIV PR structure at 2 Å resolution.
- Refinement of the crystal structure with an R-factor of 0.148.
- Enzymatic assays to measure kinetic parameters for substrate cleavage and inhibition constants for inhibitors.
Main Results:
- The crystal structure of FIV PR was successfully determined and refined.
- A statine-based inhibitor, LP-149, was found to bind to FIV PR.
- FIV PR shares structural homology with other retroviral proteinases, but HIV PR inhibitors showed limited efficacy against FIV PR.
Conclusions:
- The determined FIV PR structure enhances understanding of retroviral proteinase enzymes.
- Structural insights will guide the development and testing of new proteinase inhibitors.
- This research supports the use of a feline animal model for evaluating antiviral drug efficacy.