Diaqua­bis{[1-hydr­oxy-2-(1H-imidazol-3-ium-1-yl)ethane-1,1-di­yl]bis­(hydrogen phospho­nato)}manganese(II)

In the title compound, [Mn(C5H9N2O7P2)2(H2O)2], the MnII atom (site symmetry ) is coordinated by four phos­pho­n­ate O atoms from a pair of partially deprotonated 1-hydr­oxy-2-(imidazol-3-yl)ethane-1,1-bis­phophonic acid ligands (imhedpH3 −) and two water mol­ecules, resulting in a slightly distorted trans-MnO6 octa­hedral geometry for the metal ion. In the ligands, the imidazole units are protonated and two of the hydr­oxy O atoms of the phospho­nate groups are deprotonated and chelate the MnII, thus forming the neutral mol­ecule of the title compound. The two protonated O atoms within the phospho­nate groups of one imhedpH3 − ligand act as hydrogen-bond acceptors for a bifurcated hydrogen bond originating from the coordinated water mol­ecule. The phospho­nate units of neigboring mol­ecules are connected with their equivalents in neighboring mol­ecules via two types of inversion-symmetric hydrogen-bonding arrangements with four and two strong O—H⋯O hydrogen bonds, respectively. The two inter­actions connect mol­ecules into infinite chains along [111] and [110], in combination forming a tightly hydrogen-bonded three-dimensional supra­molecular network. This network is further stabilized by additional hydrogen bonds between the protonated imidazole units and one of the coordinated P—O O atoms and by additional O—H⋯O hydrogen bonds between the water mol­ecules and the P=O O atoms of neigboring mol­ecules

Blank peak current-suppressed electrochemical aptameric sensing platform for highly sensitive signal-on detection of small molecule

In this contribution, an electrochemical aptameric sensing scheme for the sensitive detection of small molecules is proposed using adenosine as a target model. A ferrocene (Fc)-functionalized thiolated aptamer probe is adapted and immobilized onto an electrode surface. Introducing a recognition site for EcoRI into the aptamer sequence not only suppresses the peak current corresponding to blank sample but also provides a signal-on response mechanism. In the absence of adenosine, the aptamer can fold into a hairpin structure and form a cleavable double-stranded region. Fc is capable of being removed from electrode surface by treatment with endonuclease, and almost no peak current is observed. The adenosine/aptamer binding induces the conformational transition of designed aptamer, dissociating the cleavable double-stranded segment. Therefore, the integrated aptamer sequence is maintained when exposing to endonuclease, generating a peak current of Fc. Utilizing the present sensing scheme, adenosine even at a low concentration can give a detectable current signal. Thus, a detection limit of 10−10 M and a linear response range from 3.74 × 10−9 to 3.74 × 10−5 M are achieved. The proposed proof-of-principle of a novel electrochemical sensing is expected to extend to establish various aptameric platforms for the analysis of a broad range of target molecules of interest

Amyloid-Like Aggregates of the Yeast Prion Protein Ure2 Enter Vertebrate Cells by Specific Endocytotic Pathways and Induce Apoptosis

BACKGROUND: A number of amyloid diseases involve deposition of extracellular protein aggregates, which are implicated in mechanisms of cell damage and death. However, the mechanisms involved remain poorly understood. METHODOLOGY/PRINCIPAL FINDINGS: Here we use the yeast prion protein Ure2 as a generic model to investigate how amyloid-like protein aggregates can enter mammalian cells and convey cytotoxicity. The effect of three different states of Ure2 protein (native dimer, protofibrils and mature fibrils) was tested on four mammalian cell lines (SH-SY5Y, MES23.5, HEK-293 and HeLa) when added extracellularly to the medium. Immunofluorescence using a polyclonal antibody against Ure2 showed that all three protein states could enter the four cell lines. In each case, protofibrils significantly inhibited the growth of the cells in a dose-dependent manner, fibrils showed less toxicity than protofibrils, while the native state had no effect on cell growth. This suggests that the structural differences between the three protein states lead to their different effects upon cells. Protofibrils of Ure2 increased membrane conductivity, altered calcium homeostasis, and ultimately induced apoptosis. The use of standard inhibitors suggested uptake into mammalian cells might occur via receptor-mediated endocytosis. In order to investigate this further, we used the chicken DT40 B cell line DKOR, which allows conditional expression of clathrin. Uptake into the DKOR cell-line was reduced when clathrin expression was repressed suggesting similarities between the mechanism of PrP uptake and the mechanism observed here for Ure2. CONCLUSIONS/SIGNIFICANCE: The results provide insight into the mechanisms by which amyloid aggregates may cause pathological effects in prion and amyloid diseases

Compartment-Restricted Biotinylation Reveals Novel Features of Prion Protein Metabolism in Vivo

A selective tagging method for detecting minor alternatively-localized populations of a protein is used to study a disease-associated transmembrane form of prion protein. The analysis reveals key features of transmembrane prion protein metabolism and one way this is altered by human disease-causing mutants

Deubiquitinases Sharpen Substrate Discrimination during Membrane Protein Degradation from the ER

SummaryNewly synthesized membrane proteins are queried by ubiquitin ligase complexes and triaged between degradative and nondegradative fates. The mechanisms that convert modest differences in substrate-ligase interactions into decisive outcomes of ubiquitination are not well understood. Here, we reconstitute membrane protein recognition and ubiquitination in liposomes using purified components from a viral-mediated degradation pathway. We find that substrate-ligase interactions in the membrane directly influence processivity of ubiquitin attachment to modulate polyubiquitination. Unexpectedly, differential processivity alone could not explain the differential fates in cultured cells of degraded and nondegraded clients. Both computational and experimental analyses identified continuous deubiquitination as a prerequisite for maximal substrate discrimination. Deubiquitinases reduce polyubiquitin dwell times preferentially on clients that dissociate more rapidly from the ligase. This explains how small differences in substrate-ligase interaction can be amplified into larger differences in net degradation. These results provide a conceptual framework for substrate discrimination during membrane protein quality control

Role of BMP3 in progression of gastric carcinoma in Chinese people

AIM: To investigate the relation between gastric cancer and microsatellite instability (MSI), loss of heterozygosity (LOH) and promoter region methylation

Protofibrils of Ure2 induced apoptosis of SH-SY5Y cells.

<p>(<b>A</b>) Caspase-3 activity of SH-SY5Y cells increased 5 times with respect to the control group after treatment with protofibrils. The error bars represents the S.E. of the mean of at least three independent measurements. (<b>B</b>) Apoptosis assay of SH-SY5Y cells after treatment with protofibrils. Green represents annexin V staining, indicating apoptosis. Red represents propidium iodide staining, indicating necrosis. The cells shown are representative for a total of 10 fields (more than 100 cells) that were imaged (bar = 12 µm).</p