Highly Mutable Linker Regions Regulate HIV-1 Rev Function and Stability.

Area of Science:

• Molecular Biology
• Virology
• Protein Structure-Function Relationships

Background:

• HIV-1 Rev protein is crucial for viral replication, regulating the export of viral mRNAs.
• Rev's structure includes well-defined motifs and less-understood linker regions.
• Previous studies identified constraints in Rev motifs but hinted at plasticity in linker regions.

Purpose of the Study:

• To investigate the functional and structural roles of HIV-1 Rev's linker regions.
• To determine the mutational limits of these linker regions using truncations and substitutions.
• To explore previously unrecognized functions within these less-characterized areas of Rev.

Main Methods:

• Competitive deep mutational scanning was used to identify positions of mutational plasticity.
• Truncation and mass substitution mutations were introduced to probe linker region limits.
• Functional activities of mutated Rev proteins were assessed.

Main Results:

• HIV-1 Rev linker regions possess previously unknown structural, functional, and regulatory roles.
• N- and C-termini of Rev are important for protein stability.
• Mutations in a specific turn and a linker connecting to the nuclear export sequence impact Rev function.

Conclusions:

• HIV-1 Rev function is not limited to its known motifs and is influenced by its linker regions.
• These linker regions have structural requirements for Rev's biological activity.
• Rev exhibits significant mutational and functional robustness, tolerating extensive modifications.