Impact of Genetic Variations in HIV-1 Tat on LTR-Mediated Transcription via TAR RNA Interaction.

Larance Ronsard,Sankar Pajaniradje,Suhnrita Chaudhuri,Binod Kumar,Mohane S Coumar,Tripti Rai,Devesh Rai,Subhashree Sridharan,Vivek K Singh,Nilanjana Ganguli,Akhil C Banerjea,Vishnampettai G Ramachandran,Kumaravel Mohankumar

doi:10.3389/fmicb.2017.00706

Abstract

HIV-1 evades host defense through mutations and recombination events, generating numerous variants in an infected patient. These variants with an undiminished virulence can multiply rapidly in order to progress to AIDS. One of the targets to intervene in HIV-1 replication is the trans-activator of transcription (Tat), a major regulatory protein that transactivates the long terminal repeat promoter through its interaction with trans-activation response (TAR) RNA. In this study, HIV-1 infected patients (n = 120) from North India revealed Ser46Phe (20%) and Ser61Arg (2%) mutations in the Tat variants with a strong interaction toward TAR leading to enhanced transactivation activities. Molecular dynamics simulation data verified that the variants with this mutation had a higher binding affinity for TAR than both the wild-type Tat and other variants that lacked Ser46Phe and Ser61Arg. Other mutations in Tat conferred varying affinities for TAR interaction leading to differential transactivation abilities. This is the first report from North India with a clinical validation of CD4 counts to demonstrate the influence of Tat genetic variations affecting the stability of Tat and its interaction with TAR. This study highlights the co-evolution pattern of Tat and predominant nucleotides for Tat activity, facilitating the identification of genetic determinants for the attenuation of viral gene expression.

Highlights

Human immunodeficiency virus type 1 (HIV-1) overcomes the host immune defense by rapid evolution and genetic diversification (Dougherty and Temin, 1988; Jetzt et al, 2000)
HIV-1 specimens from 120 patients were collected, and the Tat gene was amplified by polymerase chain reaction (PCR) and sequenced as described in Section “Materials and Methods.”
From 120 variants, 15 variants were chosen based on mutations in the Tat gene and these variants were segregated into three groups for long terminal repeat (LTR) transactivation study (Figure 1A)

Summary

Introduction

Human immunodeficiency virus type 1 (HIV-1) overcomes the host immune defense by rapid evolution and genetic diversification (Dougherty and Temin, 1988; Jetzt et al, 2000). Rapid replication without the benefit of proof-reading leads to the generation of a large number of mutations and recombination events (Wolinsky et al, 1996; Jetzt et al, 2000). This vigorous recombination allows HIV-1 to produce multiple groups, subtypes, sub-subtypes and recombinants in an infected patient (Wolinsky et al, 1996; Buonaguro et al, 2007). Among HIV-1 proteins, trans-activator of transcription (Tat) plays an important role in mediating the viral transcription (Okamoto et al, 1996; Zhu et al, 1997). Tat contributes to the pathogenesis of HIV-1 through its pivotal role in replication, T-cell apoptosis, coreceptor regulation, cytokine induction, and other viral activities in the host cells (Fulcher and Jans, 2003; Romani et al, 2010)

Methods

Results

Conclusion