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Glutamine synthetase (GS) is a decameric enzyme that plays a key role in nitrogen metabolism. Acetylation of the N-terminal degron (N-degron) of GS is essential for ubiquitylation and subsequent GS degradation. The full-length GS structure showed that the N-degron is buried inside the GS decamer and is inaccessible to the acetyltransferase. The structure of N-degron-truncated GS reported here reveals that the N-degron is not essential for GS decamer formation. It is also shown that the N-degron can be exposed to a solvent region through a series of conformational adjustments upon ligand binding. In summary, this study elucidated the dynamic movement of the N-degron and the possible effect of glutamine in enhancing the acetylation process.

α-Glucosidase (EC 3.2.1.20) is a carbohydrate-hydrolyzing enzyme which generally cleaves α-1,4-glycosidic bonds of oligosaccharides and starch from the nonreducing ends. In this study, the novel α-glucosidase from Weissella cibaria BBK-1 (WcAG) was biochemically and structurally characterized. WcAG belongs to glycoside hydrolase family 13 (GH13) and to the neopullanase subfamily. It exhibits distinct hydrolytic activity towards the α-1,4 linkages of short-chain oligosaccharides from the reducing end. The enzyme prefers to hydrolyse maltotriose and acarbose, while it cannot hydrolyse cyclic oligosaccharides and polysaccharides. In addition, WcAG can cleave pullulan hydrolysates and strongly exhibits transglycosylation activity in the presence of maltose. Size-exclusion chromatography and X-ray crystal structures revealed that WcAG forms a homodimer in which the N-terminal domain of one monomer is orientated in proximity to the catalytic domain of another, creating the substrate-binding groove. Crystal structures of WcAG in complexes with maltose, maltotriose and acarbose revealed a remarkable enzyme active site with accessible +2, +1 and −1 subsites, along with an Arg–Glu gate (Arg176–Glu296) in front of the active site. The −2 and −3 subsites were blocked by Met119 and Asn120 from the N-terminal domain of a different subunit, resulting in an extremely restricted substrate preference.

In this paper, the posterior probabilities of the low-density parity check (LDPC) coded bits are derived for the orthogonal frequency division multiplexing index modulation (OFDM-IM) system to reduce the implementation complexity of LDPC decoding without performance loss. Specifically, the complexity of LDPC decoding is reduced by decomposing the posterior probability of the coded bit into multiple likelihood probabilities, each of which is obtained for each subcarrier of the corresponding OFDM-IM subblock. The results of the complexity analysis indicate that the proposed approach significantly reduces the implementation complexity of LDPC decoding for OFDM-IM compared to the conventional approach. Furthermore, the simulation results confirm that the proposed approach provides the same bit error rate performance as the conventional approach.

A new type of the acoustic black hole beam—a helix-acoustic black hole—is proposed to overcome the spatial restriction on modular acoustic black hole structures. The modular acoustic black hole structure, consisted of a base and several number of acoustic black hole beams, has potential to apply into real engineering world. There are two main sections in an acoustic black hole beam: (1) a uniform thickness part and (2) an acoustic black hole region of which the thickness decreases according to the power-law profile. Conventional acoustic black hole beams can be ultimately assembled as 8–10 acoustic black hole beams on a modular acoustic black hole structure. In this article, a different shape of an acoustic black hole beam is newly designed to allow the assembly of more acoustic black hole beams on the modular acoustic black hole structure. The shape of the helix-acoustic black hole is such that the thickness of the acoustic black hole region smoothly decreases, just like a conventional acoustic black hole beam, as well as twisting along the longitudinal direction. The normal direction of the bottom surface in the uniform thickness is the same along the longitudinal axis in the conventional acoustic black hole beam. However, the normal direction of the helix-acoustic black hole of the bottom surface in the acoustic black hole region is different along the longitudinal direction. It is necessary to use numerical simulations to explore the performance of the helix-acoustic black hole beam because the shape of acoustic black hole region is different from the conventional one. Two types of numerical simulations were conducted: transient analysis and modal frequency analysis. From the transient analysis, the acoustic black hole effect was investigated by comparing the travel time which is dependent on the variation of the thickness. Using modal frequency analysis, the reflection coefficients between the conventional acoustic black hole beam and helix-acoustic black hole beam are also compared. It is noted that reflection coefficients were additionally compared depending on how “sharply” or “smoothly” they were twisted in the acoustic black hole region of the helix-acoustic black hole. Those results demonstrate that the helix-acoustic black hole has a dynamic characteristic similar to that of conventional acoustic black hole beams, which means that more helix-acoustic black holes can be assembled on the modular acoustic black hole structure by resolving the spatial restriction and leading to expectations of better performance.

We present a new approach to the design of the signal generated locally to enhance the performance in tracking of the time-multiplexed binary offset carrier (TMBOC) signal. Considering that the advantages of the TMBOC signal such as a high degree resistance to noise and multipath result from its BOC(6,1) segments, we propose to design the local signal with exploiting only BOC(6,1) segments, which is different from the conventional design approach using both BOC(6,1) and BOC(1,1) segments of the TMBOC signal. Separating and re-grouping the components composing the BOC(6,1) segments, we produce a local signal set and develop a special correlation procedure tailored to the local signal set. Numerical results indicate that the proposed approach achieves the TMBOC signal tracking with a higher degree of robustness to noise and multipath influences over that of the conventional approach in various urban canyon environments.

Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] [P(3HB-co-3HHx)] has a high potential to serve as a commercial bioplastic due to its biodegradability, thermoplastic and mechanical properties. The properties of this copolymer are greatly affected by the composition of 3HHx monomer. One of the most efficient ways to modulate the composition of 3HHx monomer in P(3HB-co-3HHx) is by manipulating the (R)-3HHx-CoA monomer supply. In this study, a new (R)-specific enoyl-CoA hydratase originating from a non-PHA producer, Streptomyces sp. strain CFMR 7 (PhaJ

We address the identification and generation of the discrete-time chaotic system (DTCS) with a two-layered recurrent neural network (RNN). First, we propose an identification procedure of the DTCS in which the RNN is required to have less layers than in the conventional procedures. Next, based on Li–Yorke theorem, we propose a generation procedure which enables us to predict a range of chaotic behavior of the DTCS in advance. Simulation results demonstrate that the proposed identification procedure, employing the Levenberg–Marquardt algorithm and a two-layered RNN, requires lower computational complexity than the conventional identification procedures at comparable performance.

An index mapping algorithm that efficiently associates the subcarrier activation pattern (SAP) or constellation mode pattern (CMP) sequences with the index selecting bit (ISB) sequences is proposed to improve the error performances of two OFDM-`index modulation' (IM) variants, OFDM-`in-phase/quadrature' (IQ)-IM and `coordinate interleaving' (CI)-`multiple-mode' (MM)-OFDM-IM. If the Hamming distances between every combinational pair of the Gray-coded ISB sequences are written in a 2-dimensional Hamming distance table, the minimum Hamming distances (i.e., 1's) are located in an X-shaped cross. In the proposed index mapping algorithm, the selection and ordering of the SAP or CMP sequences is determined by a mapping strategy of locating the minimum Hamming distances (i.e., 2's) of the SAP or CMP sequences in the same X-shaped cross as that of the minimum Hamming distances (i.e., 1's) of the Gray-coded ISB sequences. A pseudo-code is provided to reify the proposed index mapping algorithm. We show by numerical simulation that the proposed index mapping algorithm can provide substantial performance improvement for various IM schemes such as OFDM-IQ-IM, CI-MM-OFDM-IM, and OFDM-IM, especially when an error correction code is applied simultaneously.

Vesicle amine transport protein-1 (VAT-1) has been implicated in the regulation of vesicular transport, mitochondrial fusion, phospholipid transport and cell migration, and is a potential target of anticancer drugs. Little is known about the molecular function of VAT-1. The amino acid sequence indicates that VAT-1 belongs to the quinone oxidoreductase subfamily, suggesting that VAT-1 may possess enzymatic activity in unknown redox processes. To clarify the molecular function of VAT-1, we determined the three-dimensional structure of human VAT-1 in the free state at 2.3 Å resolution and found that VAT-1 forms a dimer with the conserved NADPH-binding cleft on each protomer. We also determined the structure of VAT-1 in the NADP-bound state at 2.6 Å resolution and found that NADP binds the binding cleft to create a putative active site with the nicotine ring. Substrate screening suggested that VAT-1 possesses oxidoreductase activity against quinones such as 1,2-naphthoquinone and 9,10-phenanthrenequinone.

This paper documents a tight connection between long run consumption risks (LRRs), currency excess returns and traditional global currency risk factors. We adopt a novel identification strategy that estimates country level LRRs using asset market data alone. With this identification strategy in hand, we find that: (1) currencies that suffer a bad relative LRR shock appreciate on impact before depreciating over the long run, (2) the High-Minus-Low (HML) carry trade sorts currencies on the basis of global LRR exposures, (3) the dollar carry trade outperforms on impact before underperforming over the long run in response to positive US relative LRR shocks, (4) US relative LRR shocks drive global currency risk factors. We interpret these facts as evidence in favour of an international LRR model where US LRRs drive global shocks to the world economy.

In this paper, we propose a Doppler spread estimation approach based on machine learning for an OFDM system. We present a carefully designed neural network architecture to achieve good performance in a mixed-channel scenario in which channel characteristic variables such as Rician K factor, azimuth angle of arrival (AOA) width, mean direction of azimuth AOA, and channel estimation errors are randomly generated. When preprocessing the channel state information (CSI) collected under the mixed-channel scenario, we propose averaged power spectral density (PSD) sequence as high-quality training data in machine learning for Doppler spread estimation. We detail intermediate mathematical derivatives of the machine learning process, making it easy to graft the derived results into other wireless communication technologies. Through simulation, we show that the machine learning approach using the averaged PSD sequence as training data outperforms the other machine learning approach using the channel frequency response (CFR) sequence as training data and two other existing Doppler estimation approaches.

I study the link between the US wealth share, the dollar and international risk sharing. Motivating this study are novel stylised facts regarding the US wealth share uncovered in this paper. Using aggregate portfolio holdings data, I find that: i) the US wealth share is countercyclical: the US gains relative wealth vis-a-vie the rest of the world (ROW) during global recessions, ii) these countercyclical wealth share dynamics are driven by valuation forces headlined by US equities: the US stock market outperforms the ROW during global recessions, iii) bond valuation forces associated with countercyclical convenience yields play a limited role in driving this valuation channel. I show that these wealth share dynamics along with traditional dollar dynamics can be rationalised using a simple two country recursive model of international risk sharing.

Non-thermal plasma (NTP) has been studied as a novel therapeutic tool for cancer that does not damage healthy cells. In this study, we show that NTP-treated solutions (NTS) can induce death in various leukemia cells through mechanistic target of rapamycin (mTOR) ubiquitination. Previously, we manufactured and demonstrated the efficacy of NTS in solid cancers. NTS did not exhibit any deleterious side effects, such as acute death or weight loss in nude mice. In the present study, NTS induced cell death in myeloid leukemia cells, including acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). We found that mTOR was downregulated in NTS-treated cells via the ubiquitin-proteasome system (UPS). We also identified &lsquo, really interesting new gene&rsquo, finger protein 126 (RNF126) as a novel binding protein for mTOR through protein arrays and determined the role of E3 ligase in NTS-induced mTOR ubiquitination. NTS-derived reactive oxygen species (ROS) affected RNF126 expression and lysosomal dysfunction. These findings suggest that NTS has potential antileukemic effects through RNF126-mediated mTOR ubiquitination with no deleterious side effects. Thus, NTS may represent a new therapeutic method for chemotherapy-resistant leukemia.

Summary Biodegradable polyester polyhydroxyalkanoate (PHA) is a promising bioplastic material for industrial use as a replacement for petroleum-based plastics. PHA synthase PhaC forms an active dimer to polymerize acyl moieties from the substrate acyl-coenzyme A (CoA) into PHA polymers. Here we present the crystal structure of the catalytic domain of PhaC from Chromobacterium sp. USM2, bound to CoA. The structure reveals an asymmetric dimer, in which one protomer adopts an open conformation bound to CoA, whereas the other adopts a closed conformation in a CoA-free form. The open conformation is stabilized by the asymmetric dimerization and enables PhaC to accommodate CoA and also to create the product egress path. The bound CoA molecule has its β-mercaptoethanolamine moiety extended into the active site with the terminal SH group close to active center Cys291, enabling formation of the reaction intermediate by acylation of Cys291., Graphical Abstract, Highlights • Crystal structure of PhaCCs-CAT bound to coenzyme A • A unique asymmetric open-closed dimer • Restructuring of the CAP subdomain provides a cleft toward the active site • The cleft enables the substrate entry and the product egress, Polymer Chemistry; Biocatalysis; Structural Biology

The reduction of vibration by acoustic black holes (ABHs) with damping treatments can be achieved in two stages: energy focalization and energy dissipation. The energy focalization is mainly due to changes of the local thickness by slowing down the flexural wave speed and energy dissipation can be achieved by using viscoelastic damping materials. In structures with embedded ABHs, the damping effectiveness can depend significantly on the types of damping treatments. In this paper, 4 different damping treatments according to the types of attached region are considered in order to estimate the effectiveness of damping treatments as 1) a fully-covered unconstrained damping treatment, 2) a fully-covered constrained damping treatment, 3) a partially-covered unconstrained damping treatment and 4) a partially- covered constrained damping treatment as well as no damping treatment as reference data. In this study, the performance of damping treatments is explored using numerical simulations of three-dimensional thin plate embedded truncated ABH(s). The wave energy in the ABH, the normalized total energy and the focalization ratio are introduced to compare the effectiveness of the damping treatments. The numerical results show that the fully-covered constrained damping treatment provides the most effective configuration in terms of the wave energy in ABH and the normalized total energy.

In dynamic systems, numerous structural components, such as mounts, bushings, and tires, deteriorate over time due to environmental conditions. In these elastomers, the typical environmental factor of aging is manifested by the oxidation of polymer chains due to exposure to air. The amount of oxidation in elastomers heavily depends on temperature. Elastomer components under thermal degradation show different dynamic characteristics over time. Predicting the mechanical properties of aged elastomers is crucial in structural design for enduring high-quality noise and vibration. In this work, we propose a procedure for predicting the dynamic properties of elastomers undergoing thermal degradation. This process is divided into 1) an inter-variability analysis in specific degradation states caused by uncertainties in the operational temperature environment, variation in the manufacturing process, and error of the material property model and 2) an analysis of the degradation variability caused by uncertainties in the degradation environment and the degradation model. The degradation variability includes the inter-variability and thus becomes a distribution of distributions. Therefore, the double-loop eigenvector dimension reduction method is proposed to predict degradation variability. The time–temperature superposition principle and an equivalent degradation time are introduced to accumulate the degradation states in case of thermal degradation at various temperatures. The proposed method is applied to a circular mount problem. The numerical results illustrate that the proposed method effectively predicts the aging of the dynamic elastomer properties that is due to the thermal environment.

A viral responsive protein 15 from Penaeus monodon (PmVRP15) has been reported to be important for white spot syndrome virus (WSSV) infection in vivo. This work aims to characterize PmVRP15 and investigate its possible role in nuclear import/export of the virus. Circular dichroism spectra showed that PmVRP15 contains high helical contents (82%). Analytical ultracentrifugation suggested that PmVRP15 could possibly form oligomers in solution. A subcellular fractionation study showed that PmVRP15 was found in heavy and light membrane fractions, indicating that PmVRP15 may be associated with endoplasmic reticulum. Double-stranded RNAi-mediated knockdown of PmVRP15 gene expression in vitro showed no effect on WSSV copy number in whole hemocyte cells. However, PmVRP15 silencing resulted in an accumulation of WSSV DNA in the nucleus of PmVRP15-silenced hemocytes. Immunofluorescence confocal microscopy showed that PmVRP15 knockdown hemocytes had a much lower level of VP28 (WSSV envelope protein), in comparison to that in the control. It is likely that PmVRP15 may play a role in viral nuclear egress.

SHP2 is an unusual protein phosphatase that functions as an activator for several signaling pathways, including the RAS pathway, while most other phosphatases suppress their downstream signaling cascades. The physiological and pathophysiological roles of SHP2 have been extensively studied in the field of cancer research. Mutations in the PTPN11 gene which encodes SHP2 are also highly associated with developmental disorders, such as Noonan syndrome (NS), and cognitive deficits including learning disabilities are common among NS patients. However, the molecular and cellular mechanism by which SHP2 is involved in cognitive functions is not well understood. Recent studies using SHP2 mutant mice or pharmacological inhibitors have shown that SHP2 plays critical role in learning and memory and synaptic plasticity. Here, we review the recent studies demonstrating that SHP2 is involved in synaptic plasticity, and learning and memory, by the regulation of the expression and/or function of glutamate receptors. We suggest that each cell type may have distinct paths connecting the dots between SHP2 and glutamate receptors, and these paths may also change with aging.