Arginine Methylation Increases the Stability of Human Immunodeficiency Virus Type 1 Tat
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Arginine methylation of human immunodeficiency virus type 1 (HIV-1) Tat protein downregulates its key function in viral-gene transactivation. The fate of methylated Tat is unknown, so it is unclear whether methylated Tat is degraded or persists in the cell for additional functions. Here we show that the arginine methyltransferase PRMT6 increases Tat protein half-life by 4.7-fold. Tat stabilization depends on the catalytic activity of PRMT6 and requires arginine methylation within the Tat basic domain. In contrast, HIV-1 Rev, which is also methylated by PRMT6, is completely refractory to the stabilizing effect. Proteasome inhibition and silencing experiments demonstrated that Tat can be degraded by a REG -independent proteasome, against which PRMT6 appears to act to increase Tat half-life. Our data reveal a proteasome-dependent Tat degradation pathway that is inhibited by arginine methylation. The stabilizing action of PRMT6 could allow Tat to persist within the cell and the extracellular environment and thereby enable functions implicated in AIDS-related cancer, neurodegeneration, and T-cell death.
Journal of Virology
© 2009 American Society for Microbiology. The attached file is reproduced here in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Medical Microbiology not elsewhere classified
Microbiology not elsewhere classified