Point-of-care Ultrasound for Nonangulated Distal Forearm Fractures in Children: Test Performance Characteristics and Patient-centered Outcomes.

Objectives: Distal forearm fractures are the most common fracture type in children. Point-of-care-ultrasound (POCUS) is increasingly being used, and preliminary studies suggest that it offers an accurate approach to diagnosis. However, outcomes such as pain, satisfaction, and procedure duration have not been explored but may be salient to the widespread acceptance of this technology by caregivers and children.

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 Mg2+ 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 Mg2+ 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 beta' subunit of Escherichia coli RNAP and testing the mutant enzymes' functions.

Homogeneous fluorescent assay for RNA polymerase.

A new method for determination of RNA polymerase (RNAP) activity is presented. The method uses nucleoside tri- and tetraphosphate derivatives carrying 4-methylumbelliferone residue at the terminal phosphate. Incorporation of such compounds in RNA by RNA polymerase is accompanied by release of di- and triphosphate derivatives of 4-methylumbelliferone.

Aptamers to Escherichia coli core RNA polymerase that sense its interaction with rifampicin, sigma-subunit and GreB.

Bacterial RNA polymerase (RNAP) is the central enzyme of gene expression that is responsible for the synthesis of all types of cellular RNAs. The process of transcription is accompanied by complex structural rearrangements of RNAP. Despite the recent progress in structural studies of RNAP, detailed mechanisms of conformational changes of RNAP that occur at different stages of transcription remain unknown.

Donation of catalytic residues to RNA polymerase active center by transcription factor Gre.

During transcription elongation, RNA polymerase (RNAP) occasionally loses its grip on the growing RNA end and backtracks on the DNA template. Prokaryotic Gre factors rescue the backtracked ternary elongating complex through stimulation of an intrinsic endonuclease activity, which removes the disengaged 3' RNA segment. By using RNA-protein crosslinking in defined ternary elongating complexes, site-directed mutagenesis, discriminative biochemical assays, and docking of the two protein structures, we show that Gre acts by providing two carboxylate residues for coordination of catalytic Mg2+ ion in the RNAP active center.

Unified two-metal mechanism of RNA synthesis and degradation by RNA polymerase.

In DNA-dependent RNA polymerases, reactions of RNA synthesis and degradation are performed by the same active center (in contrast to DNA polymerases in which they are separate). We propose a unified catalytic mechanism for multisubunit RNA polymerases based on the analysis of its 3'-5' exonuclease reaction in the context of crystal structure. The active center involves a symmetrical pair of Mg(2+) ions that switch roles in synthesis and degradation.

Swing-gate model of nucleotide entry into the RNA polymerase active center.

Each elementary step of transcription involves translocation of the 3' terminus of RNA in the RNA polymerase active center, followed by the entry of a nucleoside triphosphate. The structural basis of these transitions was studied using RNA-protein crosslinks. The contacts were mapped and projected onto the crystal structure, in which the "F bridge" helix in the beta' subunit is either bent or relaxed.