Inorganic phosphate, arsenate, and vanadate enhance exonuclease transcript cleavage by RNA polymerase by 2000-fold

Inorganic Pi is involved in all major biochemical pathways. Here we describe a previously unreported activity of Pi. We show that Pi and its structural mimics, vanadate and arsenate, enhance nascent transcript cleavage by RNA polymerase (RNAP). They engage an Mg2+ ion in catalysis and activate an attacking water molecule. Pi, vanadate, and arsenate stimulate the intrinsic exonuclease activity of the enzyme nearly 2,000-fold at saturating concentrations of the reactant anions and Mg2+. This enhancement is comparable to that of specialized transcript cleavage protein factors Gre and TFIIS (3,000- to 4,000-fold). Unlike these protein factors, Pi and its analogs do not stimulate endonuclease transcript cleavage. Conversely, the protein factors only marginally enhance exonucleolytic cleavage. Pi thus complements cellular protein factors in assisting hydrolytic RNA cleavage by extending the repertoire of RNAP transcript degradation modes

Quinolones: Action and Resistance Updated

The quinolones trap DNA gyrase and DNA topoisomerase IV on DNA as complexes in which the DNA is broken but constrained by protein. Early studies suggested that drug binding occurs largely along helix-4 of the GyrA (gyrase) and ParC (topoisomerase IV) proteins. However, recent X-ray crystallography shows drug intercalating between the -1 and +1 nucleotides of cut DNA, with only one end of the drug extending to helix-4. These two models may reflect distinct structural steps in complex formation. A consequence of drug-enzyme-DNA complex formation is reversible inhibition of DNA replication; cell death arises from subsequent events in which bacterial chromosomes are fragmented through two poorly understood pathways. In one pathway, chromosome fragmentation stimulates excessive accumulation of highly toxic reactive oxygen species that are responsible for cell death. Quinolone resistance arises stepwise through selective amplification of mutants when drug concentrations are above the MIC and below the MPC, as observed with static agar plate assays, dynamic in vitro systems, and experimental infection of rabbits. The gap between MIC and MPC can be narrowed by compound design that should restrict the emergence of resistance. Resistance is likely to become increasingly important, since three types of plasmid-borne resistance have been reported

The Role Of Spiritual And Educational Events In Promoting The Ideas Of Religious Tolerance And International Health.

This  article  deals  with  spiritual  and  enlightenment  propaganda  in  promoting  the  idea  of religious and interethnic tolerance. There is information about the current political and social news in this area.This  article  deals  with  spiritual  and  enlightenment  propaganda  in  promoting  the  idea  of religious and interethnic tolerance. There is information about the current political and social news in this area

The involvement of the aspartate triad of the active center in all catalytic activities of multisubunit RNA polymerase

Three conserved aspartate residues in the largest subunit of multisubunit RNA polymerases (RNAPs) coordinate two Mg(2+) ions involved in the catalysis of phosphodiester bond synthesis. A structural model based on the stereochemistry of nucleotidyl transfer reaction as well as recent crystallographic data predict that these Mg(2+) ions should also be involved in the reverse reaction of pyrophosphorolysis as well as in the endo- and exonucleolytic cleavage of the nascent RNA. Here, we check these predictions by constructing point substitutions of each of the three Asp residues in the β′ subunit of Escherichia coli RNAP and testing the mutant enzymes' functions. Using artificially assembled elongation complexes, we demonstrate that substitutions of any of the three aspartates dramatically reduce all known RNAP catalytic activities, supporting the model's predictions that same amino acids participate in all RNAP catalytic reactions. We demonstrate that though substitutions in the DFDGD motif decrease Mg(2+) binding to free RNAP below detection limits, the apparent affinity to Mg(2+) in transcription complexes formed by the mutant and wild-type RNAPs is similar, suggesting that NTP substrates and/or nucleic acids actively contribute to the retention of active center Mg(2+)

Concomitant ablation for non-paroxysmal atrial fibrillation: combined energy versus cryoablation alone

BackgroundSurgical ablation of atrial fibrillation has been the most efficient treatment for atrial fibrillation (AF). Combined energy (CE) ablation and cryoablation alone (CA) are the most common energy modes used for ablation, however, comparative data is lacking.ObjectivesTo compare the efficacy of CE ablation with CA in the setting of concomitant biatrial ablation for non-paroxysmal AF.MethodsA retrospective analysis of 453 patients with non-paroxysmal AF undergone concomitant biatrial ablation from November 2007 to December 2022 during elective cardiac surgery using either combined bipolar radiofrequency with cryoenergy or cryoenergy alone was performed. Propensity score matching was conducted to balance the covariates in the groups.ResultsThere were 157 patients per group after matching. CE ablation was associated with lower odds of atrial tachyarrhythmia recurrence (OR = 0.13, 95% CI 0.02–0.91, p = 0.040), a significantly lower rate of hospital readmissions due to rhythm disruption (HR = 0.34, 95% CI 0.18–0.65, p < 0.001), and lower cumulative incidence of stroke (SHR = 0.38, 95% CI 0.15–0.97, p = 0.043). No significant difference in permanent pacemaker implantation was observed between the two groups.ConclusionsIn the setting of concomitant biatrial ablation for non-paroxysmal AF, combined bipolar radiofrequency and cryoablation appear to be a superior treatment modality compared to cryoablation alone in achieving long-term freedom from atrial arrhythmias, in reducing arrhythmia-related hospital readmissions and ischemic strokes

Pre-detection history of extensively drug-resistant tuberculosis in KwaZulu-Natal, South Africa

Antimicrobial-resistant (AMR) infections pose a major threat to global public health. Similar to other AMR pathogens, both historical and ongoing drug-resistant tuberculosis (TB) epidemics are characterized by transmission of a limited number of predominant Mycobacterium tuberculosis (Mtb) strains. Understanding how these predominant strains achieve sustained transmission, particularly during the critical period before they are detected via clinical or public health surveillance, can inform strategies for prevention and containment. In this study, we employ whole-genome sequence (WGS) data from TB clinical isolates collected in KwaZulu-Natal, South Africa to examine the pre-detection history of a successful strain of extensively drug-resistant (XDR) TB known as LAM4/KZN, first identified in a widely reported cluster of cases in 2005. We identify marked expansion of this strain concurrent with the onset of the generalized HIV epidemic 12 y prior to 2005, localize its geographic origin to a location in northeastern KwaZulu-Natal ∼400 km away from the site of the 2005 outbreak, and use protein structural modeling to propose a mechanism for how strain-specific rpoB mutations offset fitness costs associated with rifampin resistance in LAM4/KZN. Our findings highlight the importance of HIV coinfection, high preexisting rates of drug-resistant TB, human migration, and pathoadaptive evolution in the emergence and dispersal of this critical public health threat. We propose that integrating whole-genome sequencing into routine public health surveillance can enable the early detection and local containment of AMR pathogens before they achieve widespread dispersal.HHS | NIH | National Institute of Allergy and Infectious DiseasesVoRSUNY DownstateEpidemiology and BiostatisticsN/