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Comparative analysis of native and cysteine-deficient HIV-1 reverse transcriptase
M Fischer1, R Lifshitz, T Katz
1Biotechnology General, Israel Ltd, Kiryat Weizmann, Rehovot.
Protein Expression and Purification
|August 1, 1992
Summary
Human immunodeficiency virus reverse transcriptase (RT) was studied using recombinant E. coli expression. Key cysteinyl residues were found to be dispensable for enzyme activity and heterodimer formation.
Area of Science:
- Biochemistry
- Molecular Biology
- Virology
Background:
- Human immunodeficiency virus reverse transcriptase (RT) is a key enzyme in viral replication.
- Understanding its subunit structure and active site is crucial for developing antiviral therapies.
Purpose of the Study:
- To investigate the subunit composition of recombinant human immunodeficiency virus RT.
- To elucidate the role of specific cysteinyl residues in RT enzyme activities and structural integrity.
Main Methods:
- Expression and purification of recombinant human immunodeficiency virus RT in E. coli.
- Amino acid sequencing to confirm subunit identity.
- Site-directed mutagenesis to replace cysteinyl residues with alanine.
- Assays for DNA polymerase and ribonuclease H activities.
- Evaluation of enzyme inhibition by antiviral drugs.
Main Results:
- Recombinant RT consists of 66,000 and 53,000 Da polypeptides, with identical amino termini to virion-derived RT.
- Replacement of cysteinyl residues at positions 38 and 280 with alanine did not affect DNA polymerase or ribonuclease H activities.
- The mutant RT enzyme maintained heterodimer formation and sensitivity to polymerase inhibitors.
Conclusions:
- The studied cysteinyl residues are dispensable for human immunodeficiency virus RT function and structure.
- Mutant RT lacking these cysteinyls exhibits wild-type enzyme activities and drug susceptibility.
- This finding contributes to understanding RT structure-activity relationships for drug development.