HIV-1 Gag Binds the Multi-Aminoacyl-tRNA Synthetase Complex via the EPRS Subunit

FUBP3 enhances HIV-1 transcriptional activity and regulates immune response pathways in T cells

Far-upstream element-binding protein 3 (FUBP3) was identified at actively transcribing HIV promoters through chromatin affinity purification and mass spectrometry. Known for regulating cellular processes such as transcription and translation by binding to DNAs and RNAs, FUBP3's role in HIV transcriptional regulation was previously unrecognized. This study reveals that FUBP3 enhances HIV-1 transcriptional activation by interacting with Tat and trans-activation response (TAR)-RNA, critical for boosting viral transcription through recruitment of activating factors that promote RNA polymerase II (RNAPII) elongation. Transcriptomic analysis, chromatin immunoprecipitation, and biochemical assays demonstrated that FUBP3 associates with and stabilizes TAR-RNA, in a Tat-dependent manner, and enhances Tat steady-state levels via interaction with Tat's basic domain. Suppressing FUBP3 decreased HIV-1 transcription and altered expression of host genes linked to T cell activation and inflammation, underscoring its broad regulatory impact. Additionally, FUBP3 was enriched at active promoters, confirming its role in transcriptional regulation at specific genomic locations. These findings highlight FUBP3's critical role in the HIV-1 life cycle and suggest its potential as a therapeutic target in HIV-1 infection. Additionally, this study expands our understanding of FUBP3's functions in oncogenic and inflammatory pathways.

Aminoacyl-tRNA synthetase interactions in SARS-CoV-2 infection

Aminoacyl-tRNA synthetases (aaRSs) are ancient enzymes that serve a foundational role in the efficient and accurate translation of genetic information from messenger RNA to proteins. These proteins play critical, non-canonical functions in a multitude of cellular processes. Multiple viruses are known to hijack the functions of aaRSs for proviral outcomes, while cells modify antiviral responses through non-canonical functions of certain synthetases. Recent findings have revealed that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of coronaviral disease 19 (COVID-19), utilizes canonical and non-canonical functions of aaRSs, establishing a complex interplay of viral proteins, cellular factors and host aaRSs. In a striking example, an unconventional multi-aaRS complex consisting of glutamyl-prolyl-, lysyl-, arginyl- and methionyl-tRNA synthetases interact with a previously unknown RNA-element in the 3'-end of SARS-CoV-2 genomic and subgenomic RNAs. This review aims to highlight the aaRS-SARS-CoV-2 interactions identified to date, with possible implications for the biology of host aaRSs in SARS-CoV-2 infection.

Host Cell-Virus Interaction 2.0: Viral Stratagems of Immune Evasion, Host Cellular Responses and Antiviral Counterattacks

As rightly stated by the author Mira Grant in her novel Countdown, "There is nothing so patient, in this world or any other, as a virus searching for a host" [...].

A viral pan-end RNA element and host complex define a SARS-CoV-2 regulon

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, generates multiple protein-coding, subgenomic RNAs (sgRNAs) from a longer genomic RNA, all bearing identical termini with poorly understood roles in regulating viral gene expression. Insulin and interferon-gamma, two host-derived, stress-related agents, and virus spike protein, induce binding of glutamyl-prolyl-tRNA synthetase (EPRS1), within an unconventional, tetra-aminoacyl-tRNA synthetase complex, to the sgRNA 3'-end thereby enhancing sgRNA expression. We identify an EPRS1-binding sarbecoviral pan-end activating RNA (SPEAR) element in the 3'-end of viral RNAs driving agonist-induction. Translation of another co-terminal 3'-end feature, ORF10, is necessary for SPEAR-mediated induction, independent of Orf10 protein expression. The SPEAR element enhances viral programmed ribosomal frameshifting, thereby expanding its functionality. By co-opting noncanonical activities of a family of essential host proteins, the virus establishes a post-transcriptional regulon stimulating global viral RNA translation. A SPEAR-targeting strategy markedly reduces SARS-CoV-2 titer, suggesting a pan-sarbecoviral therapeutic modality.