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Oligomerization of HIV-1 Rev mutants in the cytoplasm and during nuclear import
A M Szilvay1, K A Brokstad, S O Bøe
1Department of Microbiology and Immunology, Gade Institute, University of Bergen, Norway.
Insights
Rev protein oligomerization is crucial for its function. A new assay shows Rev mutants can import defective mutants into the nucleus, highlighting oligomerization
Area of Science:
- Molecular biology
- Virology
- Cell biology
Background:
- Rev protein oligomerization is essential for its function in viral gene expression.
- Existing methods for studying Rev oligomerization, like Western blot, primarily focus on dimer formation.
Purpose of the Study:
- To develop and validate a novel in vivo assay for analyzing Rev heteromer formation.
- To investigate the role of Rev oligomerization in cytoplasmic and nuclear import processes.
Main Methods:
- Development of an in vivo heteromerization assay utilizing Rev mutants with intact and defective nuclear localization signals (NLS).
- Assessing the ability of Rev mutants to specifically interact and translocate NLS-defective mutants into nuclear compartments.
- Evaluating Rev mutant localization in cytoplasm and nucleus.
Main Results:
- Several previously identified oligomerization-defective Rev mutants successfully mediated nuclear and nucleolar localization of NLS-defective mutants.
- The Rev M4 mutant was unique in its failure to translocate NLS-defective mutants to the nucleus.
- The M4 mutant exhibited predominantly cytoplasmic localization, suggesting impaired nuclear import.
Conclusions:
- Rev oligomerization is critical for efficient nuclear import.
- The developed in vivo assay provides a valuable tool for studying Rev heteromerization and function.
- The M4 mutant's behavior provides further evidence for the necessity of oligomerization in Rev's nuclear trafficking.
Abstract:
Oligomerization of Rev molecules has been shown to be required for Rev function. In addition to a Western blot assay monitoring dimer formation, a new in vivo assay analyzing formation of Rev heteromers in the cytoplasm and during nuclear import is presented here. The oligomerization assay is based upon the ability of Rev mutants with an intact nuclear localization signal (NLS) to interact specifically with mutants with a defective NLS and translocate such mutants to the nuclear compartments. Several of the mutants previously reported to be oligomerization defective were found to mediate nuclear and nucleolar localization of the NLS mutant. The Rev mutant previously named M4 was the only mutant tested that did not translocate the mutant with a defective NLS to the nucleus. Furthermore, the predominantly cytoplasmic localization of the M4 mutant suggests that oligomerization is important for effective nuclear import of Rev.