Structural Mechanism of the Arrestin-3/JNK3 Interaction.

Arrestins, in addition to desensitizing GPCR-induced G protein activation, also mediate G protein-independent signaling by interacting with various signaling proteins. Among these, arrestins regulate MAPK signal transduction by scaffolding mitogen-activated protein kinase (MAPK) signaling components such as MAPKKK, MAPKK, and MAPK. In this study, we investigated the binding mode and interfaces between arrestin-3 and JNK3 using hydrogen/deuterium exchange mass spectrometry, F-NMR, and tryptophan-induced Atto 655 fluorescence-quenching techniques.

Astrometrically registered maps of HO and SiO masers toward VX Sagittarii.

The supergiant VX Sagittarii is a strong emitter of both HO and SiO masers. However, previous VLBI observations have been performed separately, which makes it difficult to spatially trace the outward transfer of the material consecutively. Here we present the astrometrically registered, simultaneous maps of 22.

Dimerization facilitates the conformational transitions for bacterial phosphotransferase enzyme I autophosphorylation in an allosteric manner.

The bacterial phosphotransferase system is central to sugar uptake and phosphorylation. Enzyme I (EI), the first enzyme of the system, autophosphorylates as a dimer using phosphoenolpyruvate (PEP), but it is not clearly understood how dimerization activates the enzyme activity. Here, we show that EI dimerization is important for proper conformational transitions and the domain association required for the autophosphorylation.

Biophysical characterization of Ca-binding of S100A5 and Ca-induced interaction with RAGE.

S100A5 is a calcium-binding protein of S100 family, which represents a major ligand to the receptor for advanced glycation end product (RAGE), a pattern recognition receptor engaged in diverse pathological processes. Here we have characterized calcium binding of S100A5 and the complex formation between S100A5 and RAGE using calorimetry and NMR spectroscopy. S100A5 binds to calcium ions in a sequential manner with the equilibrium dissociation constants (K) of 1.

Conformations of JNK3α splice variants analyzed by hydrogen/deuterium exchange mass spectrometry.

c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase (MAPK) family that regulate apoptosis, inflammation, cytokine production, and metabolism. MAPKs undergo various splicing within their kinase domains. Unlike other MAPKs, JNKs have alternative splicing at the C-terminus, resulting in long and short variants.

Different conformational dynamics of various active states of β-arrestin1 analyzed by hydrogen/deuterium exchange mass spectrometry.

Arrestins have important roles in G protein-coupled receptor (GPCR) signaling including desensitization of GPCRs and G protein-independent signaling. Two major intra-molecular interactions, the polar core and the three-element region, maintain arrestins in the basal conformation by connecting the N- and C-domains. Mutations in these regions that disrupt the polar core (R169E or p44) or the three-element (3A) have been reported to interact with GPCRs in a phosphorylation-independent manner, and thus these mutants are referred to as pre-activated arrestins.

Different conformational dynamics of β-arrestin1 and β-arrestin2 analyzed by hydrogen/deuterium exchange mass spectrometry.

Arrestins have important roles in G protein-coupled receptor (GPCR) signaling including desensitization of GPCRs and G protein-independent signaling. There have been four arrestins identified: arrestin1, arrestin2 (e.g.

Thermodynamic dissection of large-scale domain motions coupled with ligand binding of enzyme I.

Domain motions are central to the biological functions of many proteins. The energetics of the motions, however, is often difficult to characterize when motions are coupled with the ligand binding. Here, we determined the thermodynamic parameters of individual domain motions and ligand binding of enzyme I (EI) using strategic domain-deletion mutants that selectively removed particular motions.

Calorimetric and spectroscopic investigation of the interaction between the C-terminal domain of Enzyme I and its ligands.

Enzyme I initiates a series of phosphotransfer reactions during sugar uptake in the bacterial phosphotransferase system. Here, we have isolated a stable recombinant C-terminal domain of Enzyme I (EIC) of Escherichia coli and characterized its interaction with the N-terminal domain of Enzyme I (EIN) and also with various ligands. EIC can phosphorylate EIN, but their binding is transient regardless of the presence of phosphoenolpyruvate (PEP).

Active site phosphoryl groups in the biphosphorylated phosphotransferase complex reveal dynamics in a millisecond time scale.

The N-terminal domain of Enzyme I (EIN) and phosphocarrier HPr can form a biphosphorylated complex when they are both phosphorylated by excess cellular phosphoenolpyruvate. Here we show that the electrostatic repulsion between the phosphoryl groups in the biphosphorylated complex results in characteristic dynamics at the active site in a millisecond time scale. The dynamics is localized to phospho-His15 and the stabilizing backbone amide groups of HPr, and does not impact on the phospho-His189 of EIN.

Survivin mediates prostate cell protection by HIF-1alpha against zinc toxicity.

Background: The prostate contains extremely high concentrations of zinc, but survives and grows without apparent injury. This begs the question as to how prostate cells avoid the toxic effects of zinc. In a previous study, the authors found that; HIF-1alpha is expressed concomitantly with the accumulation of zinc in the epithelial cells of normal rat prostates, the zinc ion stabilizes HIF-1alpha in prostate cells, and that HIF-1alpha protects prostate cells from zinc toxicity.

Activation of NMDA receptors increases proliferation and differentiation of hippocampal neural progenitor cells.

The prolonged effects of N-methyl-D-aspartate (NMDA) receptor activation on the proliferation and differentiation of hippocampal neural progenitor cells (NPCs) were studied. Under conditions of mitogen-mediated proliferation, a single NMDA pulse (5 microM) increased the fraction of 5-bromo-2-deoxyuridine (BrdU)-positive (BrdU(+)) cells after a delay of 72 hours. Similarly, a single systemic injection of NMDA (100 mg/kg) increased the number of BrdU(+) cells in the dentate gyrus (DG) after 28 days, but not after 3 days.