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Site-specific phosphorylation regulates human T-cell leukemia virus type 2 Rex function in vivo
Matthew Kesic1, Michael Ward, O John Semmes
1Center for Retrovirus Research, Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA.
Journal of Virology
|June 26, 2009
Summary
Phosphorylation of Human T-cell leukemia virus type 2 (HTLV-2) Rex protein regulates its structure and function. Key phosphorylation sites critical for Rex-2 activity and localization were identified, offering insights into viral latency.
Area of Science:
- Virology
- Molecular Biology
- Protein Biochemistry
Background:
- Human T-cell leukemia virus type 2 (HTLV-2) Rex protein regulates viral gene expression.
- Phosphorylation of Rex-2 influences its conformation, mRNA binding, and splicing inhibition.
- The phosphorylation state of Rex-2 may control HTLV-2 latency or productive infection.
Purpose of the Study:
- To perform a comprehensive phosphorylation and functional mapping of both p24(Rex) and p26(Rex) forms.
- To identify specific phosphorylation sites and evaluate their functional significance in vivo.
- To elucidate the role of phosphorylation in regulating Rex-2 structure, localization, and function.
Main Methods:
- Mammalian cell expression of Rex-2.
- Affinity purification and liquid chromatography-tandem mass spectrometry (LC-MS/MS) for phosphoproteomic analysis.
- Site-directed substitutional mutational analysis to assess functional impact.
Main Results:
- Identified two phosphorylation sites in p24(Rex) (Ser-117, Thr-164) and six in p26(Rex) (Thr-19, Ser-117, Ser-125, Ser-151, Ser-153, Thr-164).
- Phosphorylation on Thr-164, Ser-151, and Ser-153 was found to be critical for Rex-2 function in vivo.
- Phosphorylation of Ser-151 correlated with nuclear/nucleolar localization of Rex-2.
Conclusions:
- This study provides the first complete map of HTLV-2 Rex-2 phosphorylation sites.
- Phosphorylation acts as a regulatory switch, controlling Rex-2 structure, subcellular localization, and viral function.
- Understanding these phosphorylation events offers crucial insights into the regulation of HTLV-2 replication and latency.
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