System-wide investigation of ErbB4 reveals 19 sites of Tyr phosphorylation that are unusually selective in their recruitment properties

The first three members of the ErbB family of receptor tyrosine kinases activate a wide variety of signaling pathways and are frequently misregulated in cancer. Much less is known about ErbB4. Here we use tandem mass spectrometry to identify 19 sites of tyrosine phosphorylation on ErbB4, and protein microarrays to quantify biophysical interactions between these sites and virtually every SH2 and PTB domain encoded in the human genome. Our unbiased approach highlighted several previously unrecognized interactions and led to the finding that ErbB4 can recruit and activate STAT1. At a systems level, we found that ErbB4 is much more selective than the other ErbB receptors. This suggests that ErbB4 may enable ErbB2 and ErbB3 to signal independently of EGFR under normal conditions, and provides a possible explanation for the protective properties of ErbB4 in cancer.     

Fabrication of optically active flexible polymer films with embedded chain-like arrays of silver nanoparticles

We report a straightforward method for preparation of freestanding transparent polymer film containing 2D silver nanoparticle arrays and possessing polarization-sensitive optical properties.     

New catalytic route to borasiloxanes

A new, highly selective method for effective synthesis of boryl silyl ethers (borasiloxanes) via O-borylation of silanols with vinylboronates catalyzed by the Ru-H complexes [RuHCl(CO)(PCy3)2] and [RuHCl(CO)(PPh3)3] is described.     

Dependence of the size of a protein-SDS complex on detergent and Na+ concentrations

Sodium dodecyl sulfate (SDS) micelles provide ideal mimetic media for high-resolution NMR studies of membrane proteins and proteins or peptides interacting with micellar aggregates. (15)N NMR relaxation of the backbone amides of a protein-SDS complex has been measured under different experimental conditions. The rotational diffusion time of this complex has been found highly sensitive to detergent and NaCl concentrations. A comparison with calculated rotational diffusion times of protein-free SDS micelles under the same conditions suggests that the size of both aggregates must follow a similar functional dependence on detergent/NaCl concentration.     

Observation of Intact and Proteolytically Cleaved Amyloid-Beta (1–40)-Oleuropein Noncovalent Complex at Neutral pH by Mass Spectrometry

Mass spectrometry analyses carried out on mass spectrometers equipped with soft ionization sources demonstrated their utility in the assessment of the formation of noncovalent complexes and the localization of the binding sites. Direct analyses by mass spectrometry of the noncovalent complex formed in acidic and mildly acidic environments by amyloid beta (1–40) peptide and oleuropein have been previously described, and, in several studies, the absorption, metabolism, excretion, and the implications in the prevention and therapy of Alzheimer’s disease of oleuropein have been investigated. Our paper presents modifications of the method previously employed for noncovalent complex observation, namely, the amyloid beta (1–40) pretreatment, followed by an increase in the pH and replacement of the chemical environment from ammonium acetate to ammonium bicarbonate. The formation of noncovalent complexes with one or two molecules of oleuropein was detected in all chemical solutions used, and the amyloid beta (17–28) binding site was identified via proteolytic experiments using trypsin prior to and after noncovalent complex formation. Our results highlight the importance of further studies on the effect of oleuropein against amyloid beta aggregation.     

Simultaneous Determination of As,Bi, Sb,Se, Te,Hg, Pb and Sn by Small-Sized Electrothermal Vaporization Capacitively Coupled Plasma Microtorch Optical Emission Spectrometry Using Direct Liquid Microsampling

The simultaneous determination of chemical vapor-generating elements involving derivatization is difficult even by inductively coupled plasma optical emission spectrometry or mass spectrometry. This study proposes a new direct liquid microsampling method for the simultaneous determination of As, Bi, Se, Te, Hg, Pb, and Sn, using a fully miniaturized set-up based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry. The method is cost-effective, free from non-spectral interference, and easy to run by avoiding derivatization. The method involves the vaporization of analytes from the 10 µL sample and recording of episodic spectra generated in low-power (15 W) and low-Ar consumption (150 mL min⁻¹) plasma microtorch interfaced with low-resolution microspectrometers. Selective vaporization at 1300 °C ensured the avoidance of non-spectral effects and allowed the use of external calibration. Several spectral lines for each element even in the range 180–210 nm could be selected. Generally, this spectral range is examined with large-scale instrumentation. Even in the absence of derivatization, the obtained detection limits were low (0.02–0.75 mg kg⁻¹) and allowed analysis of environmental samples, such as cave and river sediments. The recovery was in the range of 86–116%, and the accuracy was better than 10%. The method is of general interest and could be implemented on any miniaturized or classical laboratory spectrometric instrumentation.     

Chemically Synthesized,Self-Assembling Small Interfering RNA-Prohead RNA Molecules Trigger Dicer-Independent Gene Silencing

RNA interference (RNAi) mediated by small interfering RNA (siRNA) duplexes is a powerful therapeutic modality, but the translation of siRNAs from the bench into clinical application has been hampered by inefficient delivery in vivo. An innovative delivery strategy involves fusing siRNAs to a three-way junction (3WJ) motif derived from the phi29 bacteriophage prohead RNA (pRNA). Chimeric siRNA-3WJ molecules are presumed to enter the RNAi pathway through Dicer cleavage. Here, we fused siRNAs to the phi29 3WJ and two phylogenetically related 3WJs. We confirmed that the siRNA-3WJs are substrates for Dicer in vitro. However, our results reveal that siRNA-3WJs transfected into Dicer-deficient cell lines trigger potent gene silencing. Interestingly, siRNA-3WJs transfected into an Argonaute 2-deficient cell line also retain some gene silencing activity. siRNA-3WJs are most efficient when the antisense strand of the siRNA duplex is positioned 5′ of the 3WJ (5′-siRNA-3WJ) relative to 3′ of the 3WJ (3′-siRNA-3WJ). This work sheds light on the functional properties of siRNA-3WJs and offers a design rule for maximizing their potency in the human RNAi pathway.     

The Unexpected Helical Supramolecular Assembly of a Simple Achiral Acetamide Tecton Generates Selective Water Channels

Achiral 2-hydroxy-N-(diphenylmethyl)acetamide (HNDPA) crystallizes in the P6₁ chiral space group as a hydrate, building up permeable chiral crystalline helical water channels. The crystallization-driven chiral self-resolution process is highly robust, with the same air-stable crystalline form readily obtained under a variety of conditions. Interestingly, the HNDPA supramolecular helix inner pore is filled by a helical water wire. The whole edifice is mainly stabilized by robust hydrogen bonds involving the HNDPA amide bonds and CH^…π interactions between the HNDPA phenyl groups. The crystalline structure shows breathing behavior, with completely reversible release and re-uptake of water inside the chiral channel under ambient conditions. Importantly, the HNDPA channel is able to transport water very efficiently and selectively under biomimetic conditions. With a permeability per channel of 3.3 million water molecules per second in large unilamellar vesicles (LUV) and total selectivity against NaCl, the HNDPA channel is a very promising functional nanomaterial for future applications.