The NS3 protein of rice hoja blanca virus complements the RNAi suppressor function of HIV‐1 Tat

Size-Independent and Noncooperative Recognition of dsRNA by the Rice Stripe Virus RNA Silencing Suppressor NS3

“…17 The exclusive siRNA-binding property of RHBV NS3 has been utilized to examine the siRNA-mediated antiviral response in mammalian cells. 36 To gain insight into the mechanism of action of NS3 and to better utilize it as a research tool, we characterize in detail the energetics of the RSV NS3 interaction with dsRNA. We analyze the association of NS3 with dsRNAs of various lengths using a combinatorial approach and derive several dsRNA binding parameters, including the stoichiometry, intrinsic binding constant, minimal binding site size, occluded site size, and cooperativity.…”

MicroRNAs and HIV-1: Complex Interactions

“…How Tat suppresses RNAi remains incompletely understood; however, the highly basic amino acid domain of Tat (58,73) can bind and sequester small RNAs, preventing their association with and activation of Dicer (74). The ability of Tat to suppress cellular RNAi function has been shown in several assays (59,75,76), including the direct delivery of Tat into neurons, which changed (by Ͼ2-fold) the expression of 50 cellular miRNAs (77). Nonetheless, it should be noted that the observed apparent RNAi activity of Tat has also been suggested to reflect an indirect effect of its transactivation of cellular promoters (78).…”

The HIV-1 Tat Protein Has a Versatile Role in Activating Viral Transcription

“…For example, Tat was shown to influence HIV-1 RNA splicing (38), capping (19,20,80), translation (15,16,18,68), and reverse transcription (3,36,43,44). Moreover, Tat has been proposed to modulate the expression of multiple cellular genes (reviewed in reference 63), to interact with a large number of cellular proteins (reference 32 and references therein), and to inhibit the cellular RNA interference mechanism (6,7,33,67). Thus, in addition to its undisputed essential function in the Tat/TAR mechanism of transcription activation, a large array of other functions has been attributed to Tat in a variety of experimental systems, although some of these functions have been questioned (51,66).…”