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Mutational analysis of human T-cell leukemia virus type 2 Tax
T M Ross1, A C Minella, Z Y Fang
1Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2363, USA.
Abstract:
A mutational analysis of human T-cell leukemia virus type 2 (HTLV-2) Tax (Tax-2) was performed to identify regions within Tax-2 important for activation of promoters through the CREB/ATF or NF-kappaB/Rel signaling pathway. Tax-2 mutations within the putative zinc-binding region as well as mutations at the carboxy terminus disrupted CREB/ATF transactivation. A single mutation within the central proline-rich region of Tax-2 disrupted the transactivation of the NF-kappaB/Rel pathway. Surprisingly, this mutation, which is thought to be in a separate activation domain, was suppressed by mutations within or around the putative zinc-binding region, suggesting an interaction between these two regions. These analyses indicate that the functional regions or domains important for transactivation through the CREB/ATF or NF-kappaB/Rel signaling pathway are similar, but not identical, in Tax-1 and Tax-2. Identification of these distinct Tax-2 mutants should facilitate comparative biological studies of HTLV-1 and HTLV-2 and ultimately lead to the determination of the functional importance of Tax trans-acting capacities in T-lymphocyte transformation by HTLV.
Insights
Mutational analysis of human T-cell leukemia virus type 2 (HTLV-2) Tax protein reveals key regions for activating signaling pathways. These findings aid in understanding HTLV-2
Area of Science:
- Virology
- Molecular Biology
- Cell Signaling
Background:
- Human T-cell leukemia virus type 2 (HTLV-2) encodes a regulatory protein, Tax-2.
- Tax proteins are crucial for viral replication and pathogenesis, including T-lymphocyte transformation.
- Understanding Tax functional domains is key to elucidating HTLV-induced diseases.
Purpose of the Study:
- To identify specific regions within HTLV-2 Tax (Tax-2) essential for activating the CREB/ATF and NF-kappaB/Rel signaling pathways.
- To compare the functional domains of Tax-2 with those of Tax-1.
Main Methods:
- Site-directed mutagenesis of the HTLV-2 Tax gene.
- Reporter gene assays to measure promoter activation via CREB/ATF and NF-kappaB/Rel pathways.
- Analysis of mutant Tax-2 protein function.
Main Results:
- Mutations in the putative zinc-binding region and carboxy terminus of Tax-2 impaired CREB/ATF transactivation.
- A mutation in the central proline-rich region disrupted NF-kappaB/Rel pathway activation.
- This central mutation's effect was suppressed by mutations near the zinc-binding region, suggesting functional interaction.
Conclusions:
- Functional domains for CREB/ATF and NF-kappaB/Rel pathway activation are largely conserved but not identical between Tax-1 and Tax-2.
- Distinct Tax-2 mutants provide tools for comparative studies of HTLV-1 and HTLV-2.
- Further research will clarify the role of Tax transactivation in HTLV-mediated T-lymphocyte transformation.