Structural and evolutionary relationships between retroviral and eucaryotic aspartic proteinases

Area of Science:

• Structural Biology
• Biochemistry
• Virology

Background:

• Retroviral proteinases (e.g., RSV PR, HIV-1 PR) are crucial for viral replication.
• Aspartic proteinases are a class of enzymes found in fungi and mammals.
• Previous studies have established structural similarities between different aspartic proteinases.

Purpose of the Study:

• To systematically compare the three-dimensional crystal structures of retroviral proteinases with eukaryotic aspartic proteinases.
• To identify conserved structural motifs and sequence similarities between these enzyme classes.
• To investigate the evolutionary relationship between retroviral and eukaryotic aspartic proteinases.

Main Methods:

• Three-dimensional structural superposition of RSV PR and HIV-1 PR with known fungal and mammalian aspartic proteinases.
• Sequence alignment of various retroviral proteinases.
• Analysis of conserved amino acid sequences and secondary structural elements.

Main Results:

• Retroviral proteinases exhibit significant structural similarity to eukaryotic aspartic proteinases, particularly in the active site regions (psi loop-alpha helix motif).
• A retroviral proteinase monomer shows structural equivalence to both N- and C-domains of eukaryotic enzymes.
• Three conserved amino acid stretches were identified in retroviral proteinases, with two related to the active site motif and one in the flap region showing no eukaryotic resemblance.
• Differences in beta sheet structures suggest potential convergent evolution.

Conclusions:

• Retroviral and eukaryotic aspartic proteinases share a common structural and potentially evolutionary origin.
• The conserved active site motifs highlight functional similarities despite distinct evolutionary paths.
• The structural divergence in other regions may indicate adaptation to specific host environments or functions.