Identification of a Phosphorylation-Dependent Nuclear Localization Motif in Interferon Regulatory Factor 2 Binding Protein 2

Background - Interferon regulatory factor 2 binding protein 2 (IRF2BP2) is a muscle-enriched transcription factor required to activate vascular endothelial growth factor-A (VEGFA) expression in muscle. IRF2BP2 is found in the nucleus of cardiac and skeletal muscle cells. During the process of skeletal muscle differentiation, some IRF2BP2 becomes relocated to the cytoplasm, although the functional significance of this relocation and the mechanisms that control nucleocytoplasmic localization of IRF2BP2 are not yet known. // Methodology/Principal Findings - Here, by fusing IRF2BP2 to green fluorescent protein and testing a series of deletion and site-directed mutagenesis constructs, we mapped the nuclear localization signal (NLS) to an evolutionarily conserved sequence 354ARKRKPSP361 in IRF2BP2. This sequence corresponds to a classical nuclear localization motif bearing positively charged arginine and lysine residues. Substitution of arginine and lysine with negatively charged aspartic acid residues blocked nuclear localization. However, these residues were not sufficient because nuclear targeting of IRF2BP2 also required phosphorylation of serine 360 (S360). Many large-scale phosphopeptide proteomic studies had reported previously that serine 360 of IRF2BP2 is phosphorylated in numerous human cell types. Alanine substitution at this site abolished IRF2BP2 nuclear localization in C2C12 myoblasts and CV1 cells. In contrast, substituting serine 360 with aspartic acid forced nuclear retention and prevented cytoplasmic redistribution in differentiated C2C12 muscle cells. As for the effects of these mutations on VEGFA promoter activity, the S360A mutation interfered with VEGFA activation, as expected. Surprisingly, the S360D mutation also interfered with VEGFA activation, suggesting that this mutation, while enforcing nuclear entry, may disrupt an essential activation function of IRF2BP2. // Conclusions/Significance - Nuclear localization of IRF2BP2 depends on phosphorylation near a conserved NLS. Changes in phosphorylation status likely control nucleocytoplasmic localization of IRF2BP2 during muscle differentiation

LUD, a new protein domain associated with lactate utilization

BACKGROUND: A novel highly conserved protein domain, DUF162 [Pfam: PF02589], can be mapped to two proteins: LutB and LutC. Both proteins are encoded by a highly conserved LutABC operon, which has been implicated in lactate utilization in bacteria. Based on our analysis of its sequence, structure, and recent experimental evidence reported by other groups, we hereby redefine DUF162 as the LUD domain family. RESULTS: JCSG solved the first crystal structure [PDB:2G40] from the LUD domain family: LutC protein, encoded by ORF DR_1909, of Deinococcus radiodurans. LutC shares features with domains in the functionally diverse ISOCOT superfamily. We have observed that the LUD domain has an increased abundance in the human gut microbiome. CONCLUSIONS: We propose a model for the substrate and cofactor binding and regulation in LUD domain. The significance of LUD-containing proteins in the human gut microbiome, and the implication of lactate metabolism in the radiation-resistance of Deinococcus radiodurans are discussed

Thoron Mitigation System based on charcoal bed for applications in thorium fuel cycle facilities (part 1): Development of theoretical models for design considerations

Regulating the environmental discharge of Rn-220 (historically known as thoron) and its decay products from thorium processing facilities is important for protection of environment and general public living in the vicinities. Activated charcoal provides an effective solution to this problem because of its high adsorption capacity to gaseous element like radon. In order to design and develop a charcoal based Thoron Mitigation System, a mathematical model has been developed in the present work for studying the Rn-220 transport and adsorption in a flow through charcoal bed and estimating the Rn-220 mitigation factor (MF) as a function of system and operating parameters. The model accounts for inter- and intragrain diffusion, advection, radioactive decay and adsorption processes. Also, the effects of large void fluctuation and wall channeling on the mitigation factor have been included through a statistical model. Closed form solution has been provided for the MF in terms of adsorption coefficient, system dimensions, grain size, flow rate and void fluctuation exponent. It is shown that the delay effects due to intra grain diffusion plays a significant role thereby rendering external equilibrium assumptions unsuitable. Also, the application of the statistical model clearly demonstrates the transition from the exponential MF to a power-law form and shows how the occurrence of channels with low probability can lower mitigation factor by several orders of magnitude. As a part of aiding design, the model is further extended to optimise the bed dimensions in respect of pressure drop and MF. The application of the results for the design and development of a practically useful charcoal bed is discussed. (C) 2017 Elsevier Ltd. All rights reserved

Thoron Mitigation System based on charcoal bed for applications in thorium fuel cycle facilities (part 2): Development, characterization, and performance evaluation

Exposure due to thoron (Rn-220) gas and its decay products in a thorium fuel cycle facility handling thorium or U-232/U-233 mixture compounds is an important issue of radiological concern requiring control and mitigation. Adsorption in a flow-through charcoal bed offers an excellent method of alleviating the release of (220R)n into occupational and public domain. In this paper, we present the design, development, and characterization of a Thoron Mitigation System (TMS) for industrial application. Systematic experiments were conducted in the TMS for examining the Rn-220 mitigation characteristics with respect to a host of parameters such as flow rate, pressure drop, charcoal grain size, charcoal mass and bed depth, water content, and heat of the carrier gas. An analysis of the experimental data shows that Rn-220 attenuation in a flow through charcoal bed is not exponential with respect to the residence time, L/U-a(L: bed depth; U-a: superficial velocity), but follows a power law behaviour, which can be attributed to the occurrence of large voids due to wall channeling in a flow through bed. The study demonstrates the regeneration of charcoal adsorption capacity degraded due to moisture adsorption, by hot air blowing technique. It is found that the mitigation factor (MF), which is the ratio of the inlet Rn-220 concentration (C-in) to the outlet Rn-220 concentration (C-out), of more than 10(4) for the TMS is easily achievable during continuous operation (>1000 h) at a flow rate of 40 Lmin(-1) with negligible (<1 cm of water column) pressure drop. The Thoron Mitigation System based on adsorption on charcoal bed offers a compact and effective device to remove Rn-220 from affluent air streams in a space constrained domain. The prototype system has been installed in a thorium fuel cycle facility where it is being evaluated for its long-term performance and overall effectiveness in mitigating Rn-220 levels in the workplace. (C) 2017 Elsevier Ltd. All rights reserved

Evaluation of radon adsorption characteristics of a coconut shell-based activated charcoal system for radon and thoron removal applications

Radon (Rn-222) thoron (Rn-220), and their decay products contribute a major fraction (more than 50%) of doses received from ionisation radiation in public domain indoor environments and occupation environments such as uranium mines, thorium plants, and underground facilities, and are recognised as important radiological hazardous materials, which need to be controlled. This paper presents studies on the removal of Rn-222 and Rn-220 from air using coconut shell-based granular activated charcoal cylindrical adsorber beds. Experiments were conducted to evaluate the Rn-222 and Rn-220 adsorption characteristics, and the mitigation efficiency of coconut-based activated charcoal available in India. The performance parameters evaluated include breakthrough time (T) and adsorption coefficient (K), and degassing characteristics of the charcoal bed of varying dimensions at different flow rates. While the breakthrough for Rn-222 occurred depending on the dimension of the adsorber bed and flow rates, for Rn-220, the breakthrough did not occur. The breakthrough curve exhibited a stretched S-shape response, instead of the theoretically predicted sharp step function. The experiments confirm that the breakthrough time individually satisfies the quadratic relationship with respect to the diameter of the bed, and the linear relationship with respect to the length, as predicted in the theory. The K value varied in the range of 2.3-4.12 m(3) kg(-1) with a mean value of 2.99 m(3) kg(-1). The K value was found to increase with the increase in flow rate. Heating the charcoal to similar to 100 degrees C resulted in degassing of the adsorbed Rn-222, and the K of the degassed charcoal and virgin charcoal were found to be similar with no deterioration in performance indicating the re-usability of the charcoal. (C) 2015 Elsevier Ltd. All rights reserved

Controlled insulator-to-metal transformation in printable polymer composites with nanometal clusters

10.1038/nmat1806Nature Materials62149-15