Expression and characterization of the reverse transcriptase enzyme from type 1 human immunodeficiency virus using...

Area of Science:

• Biochemistry
• Molecular Biology
• Virology

Background:

• Human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is essential for viral replication.
• Understanding HIV-1 RT structure and function requires large quantities of purified enzyme.
• Baculovirus expression systems offer a method for producing complex eukaryotic proteins.

Purpose of the Study:

• To produce sufficient quantities of HIV-1 p66 reverse transcriptase (RT) for structural and functional studies.
• To compare the characteristics of HIV-1 RT expressed using different baculovirus vectors.
• To investigate the role of a hexahistidine tag in recombinant HIV-1 RT activity.

Main Methods:

• Expression of HIV-1 p66 RT using two distinct baculovirus vectors (pAc373 and pBlueBacHis) in Sf158 insect cells.
• Purification of recombinant RT to high homogeneity (>90%).
• Characterization of enzyme activity, kinetic properties, and protease susceptibility.

Main Results:

• Both vectors efficiently produced HIV-1 RT. The pAc373 vector yielded a p66/p60 heterodimer, while the pBlueBacHis vector produced a hexahistidine-tagged p70/p70 homodimer (His-RT).
• His-RT exhibited lower specific activity compared to the non-tagged RT, which had activity comparable to E. coli-expressed RT.
• Removal of the hexahistidine tag from His-RT resulted in complete loss of enzyme activity, indicating the tag's importance for function.

Conclusions:

• Baculovirus expression systems are effective for producing functional HIV-1 RT.
• The N-terminal hexahistidine tag appears to be integral to the activity of the recombinant His-RT.
• Further studies are needed to elucidate the precise role of the tag in enzyme structure and function.