Related Experiment Videos
Adenoviral E1B-55kDa protein inhibits yeast mRNA export and perturbs nuclear structure
S Liang1, M Hitomi, A M Tartakoff
1Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA.
Abstract:
The mechanisms of export of RNA from the nucleus are poorly understood; however, several viral proteins modulate nucleocytoplasmic transport of mRNA. Among these are the adenoviral proteins E1B-55kDa and E4-34kDa. Late in infection, these proteins inhibit export of host transcripts and promote export of viral mRNA. To investigate the mechanism by which these proteins act, we have expressed them in Saccharomyces cerevisiae. Overexpression of either or both proteins has no obvious effect on cell growth. By contrast, overexpression of E1B-55kDa bearing a nuclear localization signal (NLS) dramatically inhibits cell growth. In this situation, the NLS-E1B-55kDa protein is localized to the nuclear periphery, fibrous material is seen in the nucleoplasm, and poly(A)+ RNA accumulates in the nucleus. Simultaneous overexpression of E4-34kDa bearing or lacking an NLS does not modify these effects. We discuss the mechanisms of selective mRNA transport.
Insights
Adenoviral proteins E1B-55kDa and E4-34kDa regulate RNA export. Nuclear localization of E1B-55kDa in yeast inhibits cell growth and causes nuclear RNA accumulation, revealing insights into nucleocytoplasmic transport.
Area of Science:
- Molecular Biology
- Cell Biology
- Virology
Background:
- Nucleocytoplasmic transport of RNA is crucial for gene expression but not fully understood.
- Viral proteins, such as adenoviral E1B-55kDa and E4-34kDa, can manipulate this process.
- These viral proteins are known to inhibit host mRNA export while promoting viral mRNA export during infection.
Purpose of the Study:
- To investigate the mechanism by which adenoviral proteins E1B-55kDa and E4-34kDa affect nucleocytoplasmic transport.
- To determine the role of nuclear localization signals in the function of these viral proteins.
- To explore selective mRNA transport mechanisms using a model system.
Main Methods:
- Expression of adenoviral proteins E1B-55kDa and E4-34kDa in Saccharomyces cerevisiae.
- Overexpression studies of wild-type and nuclear localization signal (NLS)-bearing proteins.
- Assessment of cell growth, protein localization, and poly(A)+ RNA distribution within the nucleus.
Main Results:
- Overexpression of E1B-55kDa or E4-34kDa alone had no significant effect on yeast cell growth.
- Overexpression of E1B-55kDa with a nuclear localization signal (NLS-E1B-55kDa) dramatically inhibited cell growth.
- NLS-E1B-55kDa localized to the nuclear periphery, induced fibrous material in the nucleoplasm, and caused poly(A)+ RNA to accumulate in the nucleus.
- Co-expression of E4-34kDa did not alter the effects observed with NLS-E1B-55kDa.
Conclusions:
- The nuclear localization of adenoviral E1B-55kDa is critical for its inhibitory effect on cell growth and RNA export.
- The yeast model system is useful for studying viral modulation of nucleocytoplasmic transport.
- These findings provide insights into the mechanisms of selective mRNA export and viral interference with host cell processes.