Live Imaging and Interactome Analysis of Zika and Chikungunya Viral RNAs Via Dual-Action Aptamer Tag.

Arthropod-borne, positive-sense RNA viruses encompass many human pathogens posing significant health threats worldwide. Understanding intracellular dynamics and host-factor interactions of the viral genome is essential for devising effective antiviral strategies. We engineered dual-labeled Zika and chikungunya viruses incorporating a Mango-II aptamer for RNA pulldown and real-time imaging, achieving high-resolution imaging of flavivirus RNA in live cells.

Atomic-resolution structure of a chimeric Powassan tick-borne flavivirus.

Powassan virus (POWV) is an emerging tick-borne flavivirus for which no vaccine or antiviral treatment exists. The incidence of human infections of POWV in North America has been increasing because of the expanding distribution of the tick vector that transmits POWV to humans. To mitigate the dangers of handling a risk group 3 human pathogen, a chimeric virus was constructed from the genetic backbone of a yellow fever virus vaccine strain 17D (YFV-17D) and the external structural proteins of POWV lineage II.

Granular cell ameloblastoma: A rare case report with public health implications.

Rationale: Ameloblastomas are benign odontogenic tumors that exhibit local aggressiveness and a high potential for recurrence. Their histopathological diversity and potential to cause significant anatomical and functional complications often make diagnosis and treatment challenging. This case highlights the clinical, radiographic, and histopathological features of a rare granular cell ameloblastoma and underscores the importance of a radical surgical approach to management.

Zika virus NS1 drives tunneling nanotube formation for mitochondrial transfer and stealth transmission in trophoblasts.

Zika virus (ZIKV) is unique among orthoflaviviruses in its vertical transmission capacity in humans, yet the underlying mechanisms remain incompletely understood. Here, we show that ZIKV induces tunneling nanotubes (TNTs) in placental trophoblasts which facilitate transfer of viral particles, proteins, mitochondria, and RNA to neighboring uninfected cells. TNT formation is driven exclusively via ZIKV non-structural protein 1 (NS1).

Acetylresveratrol (AC-Res): An Evolving Frontier in Modulating Gene Expression.

Background: Acetylresveratrol (AC-Res), to date, is a powerful stilbene phytoalexin generated organically or as a component of a plant's defensive system, is a significant plant phenolic chemical portion and is investigated as a therapy option for a number of disorders. Owing to its inadequate stabilisation and considerable conformation rigidity, the utility of AC-Res as a medication is limited.

Objective: The current review article outlined the structure of AC-Res, their methods of activity, and the latest technological progress in the administration of these molecules.

Identification of a critical role for ZIKV capsid α3 in virus assembly and its genetic interaction with M protein.

Flaviviruses such as Zika and dengue viruses are persistent health concerns in endemic regions worldwide. Efforts to combat the spread of flaviviruses have been challenging, as no antivirals or optimal vaccines are available. Prevention and treatment of flavivirus-induced diseases require a comprehensive understanding of their life cycle.

Zika Virus NS1 Drives Tunneling Nanotube Formation for Mitochondrial Transfer, Enhanced Survival, Interferon Evasion, and Stealth Transmission in Trophoblasts.

Zika virus (ZIKV) infection continues to pose a significant public health concern due to limited available preventive measures and treatments. ZIKV is unique among flaviviruses in its vertical transmission capacity (i.e.

Zika virus M protein latches and locks the E protein from transitioning to an immature state after prM cleavage.

During flavivirus maturation, the structural proteins prM (pre-membrane) and E (envelope) undergo extensive low pH-mediated conformational changes, transitioning from spiky trimeric to smooth dimeric prM/E heterodimers which allow for furin cleavage of prM into pr and M and forms the irreversible mature conformation of smooth M/E heterodimers. The mechanisms of irreversible conformational changes to E protein following the pr cleavage are not understood. Utilizing cryo-EM structures of immature virus and structure-based mutagenesis of Zika virus, we identified two critical "latching and locking" interactions mediated by M protein residues Arg38 and Trp19, respectively, that stabilize the E protein structure in the smooth mature stage.

Identification of SARS-CoV-2 inhibitors targeting Mpro and PLpro using in-cell-protease assay.

SARS-CoV-2 proteases Mpro and PLpro are promising targets for antiviral drug development. In this study, we present an antiviral screening strategy involving a novel in-cell protease assay, antiviral and biochemical activity assessments, as well as structural determinations for rapid identification of protease inhibitors with low cytotoxicity. We identified eight compounds with anti-SARS-CoV-2 activity from a library of 64 repurposed drugs and modeled at protease active sites by in silico docking.

Structure-based inhibitor design and repurposing clinical drugs to target SARS-CoV-2 proteases.

SARS-CoV-2, the coronavirus responsible for the current COVID-19 pandemic, encodes two proteases, 3CLpro and PLpro, two of the main antiviral research targets. Here we provide an overview of the structures and functions of 3CLpro and PLpro and examine strategies of structure-based drug designing and drug repurposing against these proteases. Rational structure-based drug design enables the generation of potent and target-specific antivirals.

Deciphering the enigma of missing DNA binding domain of LacI family transcription factors.

Catabolite repressor activator (Cra) is a member of the LacI family transcriptional regulator distributed across a wide range of bacteria and regulates the carbon metabolism and virulence gene expression. In numerous studies to crystallize the apo form of the LacI family transcription factor, the N-terminal domain (NTD), which functions as a DNA-binding domain, has been enigmatically missing from the final resolved structures. It was speculated that the NTD is disordered or unstable and gets cleaved during crystallization.

A Chemical Strategy for Intracellular Arming of an Endogenous Broad-Spectrum Antiviral Nucleotide.

The naturally occurring nucleotide 3'-deoxy-3',4'-didehydro-cytidine-5'-triphosphate () was recently found to exert potent and broad-spectrum antiviral activity. However, nucleoside 5'-triphosphates in general are not cell-permeable, which precludes the direct use of as a therapeutic. To harness the therapeutic potential of this endogenous antiviral nucleotide, we synthesized phosphoramidate prodrug HLB-0532247 () and found it to result in dramatically elevated levels of in cells.

A synthetic defective interfering SARS-CoV-2.

Viruses thrive by exploiting the cells they infect, but in order to replicate and infect other cells they must produce viral proteins. As a result, viruses are also susceptible to exploitation by defective versions of themselves that do not produce such proteins. A defective viral genome with deletions in protein-coding genes could still replicate in cells coinfected with full-length viruses.

The Prolyl-tRNA Synthetase Inhibitor Halofuginone Inhibits SARS-CoV-2 Infection.

We identify the prolyl-tRNA synthetase (PRS) inhibitor halofuginone , a compound in clinical trials for anti-fibrotic and anti-inflammatory applications , as a potent inhibitor of SARS-CoV-2 infection and replication. The interaction of SARS-CoV-2 spike protein with cell surface heparan sulfate (HS) promotes viral entry . We find that halofuginone reduces HS biosynthesis, thereby reducing spike protein binding, SARS-CoV-2 pseudotyped virus, and authentic SARS-CoV-2 infection.

Identification of a pocket factor that is critical to Zika virus assembly.

Zika virus (ZIKV) is an emerging mosquito borne flavivirus and a major public health concern causing severe disease. Due to the presence of a lipid membrane and structural heterogeneity, attaining an atomic resolution structure is challenging, but important to understand virus assembly and life cycle mechanisms that offer distinct targets for therapeutic intervention. We here use subvolume refinement to achieve a 3.

SARS-CoV-2 Infection Depends on Cellular Heparan Sulfate and ACE2.

We show that SARS-CoV-2 spike protein interacts with both cellular heparan sulfate and angiotensin-converting enzyme 2 (ACE2) through its receptor-binding domain (RBD). Docking studies suggest a heparin/heparan sulfate-binding site adjacent to the ACE2-binding site. Both ACE2 and heparin can bind independently to spike protein in vitro, and a ternary complex can be generated using heparin as a scaffold.

SARS-CoV-2 Infection Depends on Cellular Heparan Sulfate and ACE2.

We show that SARS-CoV-2 spike protein interacts with cell surface heparan sulfate and angiotensin converting enzyme 2 (ACE2) through its Receptor Binding Domain. Docking studies suggest a putative heparin/heparan sulfate-binding site adjacent to the domain that binds to ACE2. In vitro, binding of ACE2 and heparin to spike protein ectodomains occurs independently and a ternary complex can be generated using heparin as a template.

Regulating E-cigarettes in India: A conundrum for the global giant in tobacco production.

Electronic cigarettes which are termed as e-cigarettes, e-cigs or e-vaporizers are used by the people for creating the inhalable aerosol which carries nicotine in it. Also, commonly referred as vaping. E-cigarettes are used as an alternative to the regular cigarettes and aids in the cessation of smoking.

A national approach to pharmacovigilance: The case of India as a growing hub of global clinical trials.

Pharmacovigilance is the pharmacological science associated with the detection, understanding and prevention of adverse effects, especially long-term and short-term adverse effects of medicines. In the present day pharmaceutical scenario, where the development and marketing of an ever-growing array of medicines has rendered their safety and therapeutic efficacy key to determining the success of a drug, pharmacovigilance has come about to play a critical and significant part. While pharmacovigilance, as a system, has witnessed considerable progress and evolution in the West, not as much has been accomplished in India.

Cryo-EM structure of σ RNA polymerase and promoter DNA complex revealed a role of σ non-conserved region during the open complex formation.

First step of gene expression is transcribing the genetic information stored in DNA to RNA by the transcription machinery including RNA polymerase (RNAP). In , a primary σ factor forms the RNAP holoenzyme to express housekeeping genes. The σ contains a large insertion between the conserved regions 1.

Optogenetic regulation of site-specific subtelomeric DNA methylation.

Telomere length homeostasis, critical for chromosomal integrity and genome stability, is controlled by intricate molecular regulatory machinery that includes epigenetic modifications. Here, we examine site-specific and spatiotemporal alteration of the subtelomeric methylation of CpG islands using optogenetic tools to understand the epigenetic regulatory mechanisms of telomere length maintenance. Human DNA methyltransferase3A (DNMT3A) were assembled selectively at chromosome ends by fusion to cryptochrome 2 protein (CRY2) and its interacting complement, the basic helix loop helix protein-1 (CIB1).

An asymmetric heterodomain interface stabilizes a response regulator-DNA complex.

Two-component signal transduction systems consist of pairs of histidine kinases and response regulators, which mediate adaptive responses to environmental cues. Most activated response regulators regulate transcription by binding tightly to promoter DNA via a phosphorylation-triggered inactive-to-active transition. The molecular basis for formation of stable response regulator-DNA complexes that precede the assembly of RNA polymerases is unclear.

Identification of the dimer interface of a bacterial Ca(2+)/H(+) antiporter.

Members of the calcium/cation antiporter superfamily, including the cardiac sodium/calcium exchangers, are secondary active transporters that play an essential role in cellular Ca(2+) homeostasis. A notable feature of this group of transporters is the high levels of sequence similarity in relatively short sequences constituting the functionally important α-1 and α-2 regions in contrast to relatively lower degrees of similarity in the extended adjoining sequences. This suggests a similar structure and function of core transport machinery but possible differences in topology and/or oligomerization, a topic that has not been adequately addressed.

Structure-function studies of DNA binding domain of response regulator KdpE reveals equal affinity interactions at DNA half-sites.

Expression of KdpFABC, a K(+) pump that restores osmotic balance, is controlled by binding of the response regulator KdpE to a specific DNA sequence (kdpFABC(BS)) via the winged helix-turn-helix type DNA binding domain (KdpE(DBD)). Exploration of E. coli KdpE(DBD) and kdpFABC(BS) interaction resulted in the identification of two conserved, AT-rich 6 bp direct repeats that form half-sites.

Restrained expression, a method to overproduce toxic membrane proteins by exploiting operator-repressor interactions.

A major rate-limiting step in determining structures of membrane proteins is heterologous protein production. Toxicity often associated with rapid overexpression results in reduced biomass along with low yields of target protein. Mitigation of toxic effects was achieved using a method we call "restrained expression," a controlled reduction in the frequency of transcription initiation by exploiting the infrequent transitions of Lac repressor to a free state from its complex with the lac-operator site within a T7lac promoter that occur in the absence of the inducer isopropyl β-D-1-thiogalactopyranoside.