The linker between the dimerization and catalytic domains of the CheA histidine kinase propagates changes in structure and dynamics that are important for enzymatic activity.

The histidine kinase, CheA, couples environmental stimuli to changes in bacterial swimming behavior, converting a sensory signal to a chemical signal in the cytosol via autophosphorylation. The kinase activity is regulated in the platform of chemotaxis signaling complexes formed by CheW, chemoreceptors, and the regulatory domain of CheA. Our previous computational and mutational studies have revealed that two interdomain linkers play important roles in CheA's enzymatic activity.

A genetically-encoded chloride and pH sensor for dissociating ion dynamics in the nervous system.

Within the nervous system, intracellular Cl(-) and pH regulate fundamental processes including cell proliferation, metabolism, synaptic transmission, and network excitability. Cl(-) and pH are often co-regulated, and network activity results in the movement of both Cl(-) and H(+). Tools to accurately measure these ions are crucial for understanding their role under physiological and pathological conditions.

Visualizing side chains of invisible protein conformers by solution NMR.

Sparsely populated and transiently formed protein conformers can play key roles in many biochemical processes. Understanding the structure function paradigm requires, therefore, an atomic-resolution description of these rare states. However, they are difficult to study because they cannot be observed using standard biophysical techniques.

Serotonin 2C receptor antagonists induce fast-onset antidepressant effects.

Current antidepressants must be administered for several weeks to produce therapeutic effects. We show that selective serotonin 2C (5-HT2C) antagonists exert antidepressant actions with a faster-onset (5 days) than that of current antidepressants (14 days) in mice. Subchronic (5 days) treatment with 5-HT2C antagonists induced antidepressant behavioral effects in the chronic forced swim test (cFST), chronic mild stress (CMS) paradigm and olfactory bulbectomy paradigm.

Identification of evidence-based interventions for promoting HIV medication adherence: findings from a systematic review of U.S.-based studies, 1996-2011.

A systematic review was conducted to identify evidence-based interventions (EBIs) for increasing HIV medication adherence behavior or decreasing HIV viral load among persons living with HIV (PLWH). We conducted automated searches of electronic databases (i.e.

The ZIP5 ectodomain co-localizes with PrP and may acquire a PrP-like fold that assembles into a dimer.

The cellular prion protein (PrP(C)) was recently observed to co-purify with members of the LIV-1 subfamily of ZIP zinc transporters (LZTs), precipitating the surprising discovery that the prion gene family descended from an ancestral LZT gene. Here, we compared the subcellular distribution and biophysical characteristics of LZTs and their PrP-like ectodomains. When expressed in neuroblastoma cells, the ZIP5 member of the LZT subfamily was observed to be largely directed to the same subcellular locations as PrP(C) and both proteins were seen to be endocytosed through vesicles decorated with the Rab5 marker protein.

Factors that influence in vitro cholesterol deposition on contact lenses.

Purpose: The purpose of this study was to analyze the impact that incubation time, lipid concentration, and solution replenishment have on silicone hydrogel (SiHy) and conventional hydrogel (CH) contact lens cholesterol deposition via in vitro radiochemical experiments.

Methods: Four SiHy (senofilcon A, lotrafilcon B, comfilcon A, balafilcon A) and two CH (etafilcon A and omafilcon A) contact lenses were incubated in an artificial tear solution (ATS) that contained major tear film proteins, lipids, salts, salts, and a trace amount of radioactive C-cholesterol. Lenses were incubated for various incubation times (1, 3, 7, 14, or 28 days), with three concentrations of lipid (0.

Phosphorylation of the actin binding protein Drebrin at S647 is regulated by neuronal activity and PTEN.

Defects in actin dynamics affect activity-dependent modulation of synaptic transmission and neuronal plasticity, and can cause cognitive impairment. A salient candidate actin-binding protein linking synaptic dysfunction to cognitive deficits is Drebrin (DBN). However, the specific mode of how DBN is regulated at the central synapse is largely unknown.

NMR paves the way for atomic level descriptions of sparsely populated, transiently formed biomolecular conformers.

The importance of dynamics to biomolecular function is becoming increasingly clear. A description of the structure-function relationship must, therefore, include the role of motion, requiring a shift in paradigm from focus on a single static 3D picture to one where a given biomolecule is considered in terms of an ensemble of interconverting conformers, each with potentially diverse activities. In this Perspective, we describe how recent developments in solution NMR spectroscopy facilitate atomic resolution studies of sparsely populated, transiently formed biomolecular conformations that exchange with the native state.

Defining a length scale for millisecond-timescale protein conformational exchange.

Although atomic resolution 3D structures of protein native states and some folding intermediates are available, the mechanism of interconversion between such states remains poorly understood. Here we study the four-helix bundle FF module, which folds via a transiently formed and sparsely populated compact on-pathway intermediate, I. Relaxation dispersion NMR spectroscopy has previously been used to elucidate the 3D structure of this intermediate and to establish that the conformational exchange between the I and the native, N, states of the FF domain is driven predominantly by water dynamics.

Measurement of active site ionization equilibria in the 670 kDa proteasome core particle using methyl-TROSY NMR.

The 20S proteasome core particle is a molecular machine that plays a central role in the regulation of cellular function through proteolysis, and it has emerged as a valuable drug target for certain classes of cancers. Central to the development of new and potent pharmaceuticals is an understanding of the mechanism by which the proteasome cleaves substrates. A number of high-resolution structures of the 20S proteasome with and without inhibitors have emerged that provide insight into the chemistry of peptide bond cleavage and establish the role of Thr1 Oγ1 as the catalytic nucleophile.

Characterization of the EP receptor subtype that mediates the inhibitory effects of prostaglandin E2 on IgE-dependent secretion from human lung mast cells.

Background: Prostaglandin E2 (PGE2 ) has been shown to inhibit IgE-dependent histamine release from human lung mast cells. This effect of PGE2 is believed to be mediated by EP2 receptors. However, definitive evidence that this is the case has been lacking in the absence of EP2 -selective antagonists.

A computational study of the effects of (13) C-(13) C scalar couplings on (13) C CEST NMR spectra: towards studies on a uniformly (13) C-labeled protein.

Read the label: The NMR CEST experiment can be used to reconstruct spectra of sparsely populated, transiently formed protein conformers so long as they exchange with a highly populated ground state with rates of 20-300 s(-1) . Here we establish that accurate (13) C chemical shifts of side-chain carbon nuclei can be obtained from uniformly (13) C-labeled samples, without interference from the coupled (13) C spin network.

The role of interleukin-1 and interleukin-18 in pro-inflammatory and anti-viral responses to rhinovirus in primary bronchial epithelial cells.

Human Rhinovirus (HRV) is associated with acute exacerbations of chronic respiratory disease. In healthy individuals, innate viral recognition pathways trigger release of molecules with direct anti-viral activities and pro-inflammatory mediators which recruit immune cells to support viral clearance. Interleukin-1alpha (IL-1α), interleukin-1beta (IL-1β) and interleukin-18 (IL-18) have critical roles in the establishment of neutrophilic inflammation, which is commonly seen in airways viral infection and thought to be detrimental in respiratory disease.

Bladder symptoms among polio survivors.

Objective: To describe bladder symptoms among polio survivors and the inconvenience they cause.

Design: A survey using the validated Danish Prostatic Symptom Score questionnaire concerning bladder symptoms.

Subjects: A random age- and gender-stratified sample of polio survivors drawn from members of the Danish Society of Polio and Accident Victims.

Estimating side-chain order in [U-2H;13CH3]-labeled high molecular weight proteins from analysis of HMQC/HSQC spectra.

A simple approach for quantification of methyl-containing side-chain mobility in high molecular weight methyl-protonated, uniformly deuterated proteins is described, based on the measurement of peak intensities in methyl (1)H-(13)C HMQC and HSQC correlation maps and relaxation rates of slowly decaying components of methyl (1)H-(13)C multiple-quantum coherences. A strength of the method is that [U-(2)H;(13)CH3]-labeled protein samples are required that are typically available at an early stage of any analysis. The utility of the methodology is demonstrated with applications to three protein systems ranging in molecular weight from 82 to 670 kDa.

Membrane-dependent modulation of the mTOR activator Rheb: NMR observations of a GTPase tethered to a lipid-bilayer nanodisc.

Like most Ras superfamily proteins, the GTPase domain of Ras homologue enriched in brain (Rheb) is tethered to cellular membranes through a prenylated cysteine in a flexible C-terminal region; however, little is known about how Rheb or other GTPases interact with the membrane or how this environment may affect their GTPase functions. We used NMR methods to characterize Rheb tethered to nanodiscs, monodisperse protein-encapsulated lipid bilayers with a diameter of 10 nm. Membrane conjugation markedly reduced the rate of intrinsic nucleotide exchange, while GTP hydrolysis was unchanged.

A systematic review to identify challenges of demonstrating efficacy of HIV behavioral interventions for gay, bisexual, and other men who have sex with men (MSM).

Gay, bisexual, and other men who have sex with men (MSM) are disproportionately affected by HIV but few MSM-specific evidence-based interventions (EBIs) have been identified for this vulnerable group. We conducted a systematic review to identify reasons for the small number of EBIs for MSM. We also compared study, intervention and sample characteristics of EBIs versus non-EBIs to better understand the challenges of demonstrating efficacy evidence.