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HIV Protease Hinge Region Insertions at Codon 38 Affect Enzyme Kinetics, Conformational Stability and Dynamics
Zaahida Sheik Ismail1, Roland Worth1, Salerwe Mosebi2
1Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of Witwatersrand, Johannesburg, 2050, South Africa.
The Protein Journal
|July 8, 2023
Summary
A novel HIV-1 protease variant with a double amino acid insertion shows altered enzyme kinetics and increased stability. This variant
Area of Science:
- Biochemistry
- Structural Biology
- Virology
Background:
- HIV-1 protease is crucial for viral maturation and a key target for antiretroviral therapy.
- Understanding protease variants is essential for developing effective HIV treatments.
Purpose of the Study:
- To characterize a novel HIV-1 subtype C protease variant with a double amino acid insertion at position 38.
- To investigate the impact of this insertion on enzyme kinetics, stability, and dynamics.
Main Methods:
- Modified purification protocol for the HIV-1 protease variant.
- Isothermal titration calorimetry and differential scanning calorimetry for stability and conformational analysis.
- Molecular dynamics simulations to assess structural dynamics and flexibility.
Main Results:
- The variant protease showed reduced specific activity and kcat but a 1.6-fold increase in kcat/KM compared to wild type.
- Differential scanning calorimetry revealed a 5°C increase in Tm, indicating enhanced thermal stability.
- Molecular dynamics simulations showed increased stability, compactness, and flexibility in specific regions, with a preference for closed flap conformations.
Conclusions:
- The double amino acid insertion significantly impacts HIV-1 protease enzyme kinetics and conformational stability.
- The variant's altered dynamics and preference for closed flap conformations suggest a potential mechanism for drug resistance.
- This study provides insights into the structural and functional consequences of protease mutations in HIV-1 subtype C.
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