Structural basis of dimerization and dual W-box DNA recognition by rice WRKY domain.

In rice, the critical regulator of the salicylic acid signalling pathway is OsWRKY45, a transcription factor (TF) of the WRKY TF family that functions by binding to the W-box of gene promoters, but the structural basis of OsWRKY45/W-box DNA recognition is unknown. Here, we show the crystal structure of the DNA binding domain of OsWRKY45 (OsWRKY45-DBD, i.e. the WRKY and zinc finger domain) in complex with a W-box DNA. Surprisingly, two OsWRKY45-DBD molecules exchange ß4-ß5 strands to form a dimer. The domain swapping occurs at the hinge region between the ß3 and ß4 strands, and is bridged and stabilized by zinc ion via coordinating residues from different chains. The dimer contains two identical DNA binding domains that interact with the major groove of W-box DNA. In addition to hydrophobic and direct hydrogen bonds, water mediated hydrogen bonds are also involved in base-specific interaction between protein and DNA. Finally, we discussed the cause and consequence of domain swapping of OsWRKY45-DBD, and based on our work and that of previous studies present a detailed mechanism of W-box recognition by WRKY TFs. This work reveals a novel dimerization and DNA-binding mode of WRKY TFs, and an intricate picture of the WRKY/W-box DNA recognition.

Adsorptive removal of trace thallium(I) from wastewater: A review and new perspectives.

Thallium is an emerging pollutant reported in wastewater along with the increasing mining and smelting of thallium-containing ores in recent years. The complete removal of Tl(I) from wastewater is of significant emergency due to its high toxicity and mobility, however, Tl(I) removal is always confronted with numerous technical difficulties because of the extremely low Tl(I) concentration in wastewater and the disturbances of many accompanying impurity ions. Adsorption is currently the most widely used method for Tl(I) removal on industrial scale and varied kinds of adsorbents such as Prussian blue analogues, biosorbents, and metal oxides have been developed. However, the adsorption process of Tl(I) is always affected by the co-existing cations, resulting in low Tl(I) removal efficiency. Recently, the development of a variety of novel adsorbents or ion sensors based on macrocyclic compounds for enrichment and accurate determination of trace Tl(I) in aqueous solutions exhibits great potential for application in Tl(I) removal from wastewater with high selectivity and process efficiency. This paper provides an overview of the adsorption methods for Tl(I) removal from wastewater with emphasis on complexation properties between varied types of adsorbents and Tl(I). Future directions of research and development of adsorptive Tl(I) removal from industrial wastewater are proposed.

Nonlinear optical properties ofBaAlBO3F2 crystal.

We investigated the nonlinear optical properties of new BaAlBO(3)F(2)(BABF) crystal. The high quality BABF is nonhygroscopic and possesses a moderate birefringence suitable for UV light generation. On the basis of its refractive index dispersion curves, it is inferred that BABF has great potential applications nonlinear optical material, notably for UV light generation at 355 nm. In order to characterize its nonlinear optical properties, BABF samples were cut an oriented in phase matching conditions The optical conversion efficiency from 1064 nm to 532 nm was investigated for the first time: up to 49.0% were achieved. The external angular acceptance bandwidth of SHG and THG for 1064 nm pump light was measured.

Stable operation of 4 mW nanoseconds radiation at 177.3 nm by second harmonic generation in KBe2BO3F2 crystals.

We report the generation of nanoseconds radiation at 177.3 nm with a maximum average power of 34.7 mW by second harmonic generation (SHG) in a 2.06-mm thick KBe(2)BO(3)F(2) (KBBF) crystal pumped with a homemade 4.2 W nanoseconds Nd: YAG laser at 355 nm operating at 10 KHz and 49 ns, which corresponds to an energy efficiency of approximately 0.826%. To our knowledge, it is the highest power generated at 177.3 nm. The dependence of phase matching angle of KBBF on temperature is presented for the first time. We also present the details on the measures for stable operation of a 4 mW nanosecond output at 177.3 nm with a lower pumping power in a thinner 1.37-mm KBBF crystal, and the stable output power is improved by about 20 times compared with previous results.

Enhanced Phase Transition Properties of VO2 Thin Films on 6H-SiC (0001) Substrate Prepared by Pulsed Laser Deposition.

For growing high quality epitaxial VO2 thin films, the substrate with suitable lattice parameters is very important if considering the lattice matching. In addition, the thermal conductivity between the substrate and epitaxial film should be also considered. Interestingly, the c-plane of hexagonal 6H-SiC with high thermal conductivity has a similar lattice structure to the VO2 (010), which enables epitaxial growth of high quality VO2 films on 6H-SiC substrates. In the current study, we deposited VO2 thin films directly on 6H-SiC (0001) single-crystal substrates by pulsed laser deposition (PLD) and systematically investigated the crystal structures and surface morphologies of the films as the function of growth temperature and film thickness. With optimized conditions, the obtained epitaxial VO2 film showed pure monoclinic phase structure and excellent phase transition properties. Across the phase transition from monoclinic structure (M1) to tetragonal rutile structure (R), the VO2/6H-SiC (0001) film demonstrated a sharp resistance change up to five orders of magnitude and a narrow hysteresis width of only 3.3 °C.

Fabrication of NiO/NiCo2O4 Mixtures as Excellent Microwave Absorbers.

The NiO/NiCo2O4 mixtures with unique yolk-shell structure were synthesized by a simple hydrothermal route and subsequent thermal treatment. The elemental distribution, composition, and microstructure of the samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and scanning electron microscope (SEM), respectively. The microwave absorption property was investigated by using vector network analysis (VNA). The results indicated that the excellent electromagnetic wave absorption property of the NiO/NiCo2O4 mixtures was achieved due to the unique yolk-shell structure. In detail, the maximum reflection loss (RL) value of the sample reached up to - 37.0 dB at 12.2 GHz and the absorption bandwidth with RL below - 10 dB was 4.0 GHz with a 2.0-mm-thick absorber. In addition, the NiO/NiCo2O4 mixtures prepared at high temperature, exhibited excellent thermal stability. Possible mechanisms were investigated for improving the microwave absorption properties of the samples.

Substitution of tryptophan 89 with tyrosine switches the DNA binding mode of PC4.

PC4, a well-known general transcription cofactor, has multiple functions in transcription and DNA repair. Residue W89, is engaged in stacking interactions with DNA in PC4, but substituted by tyrosine in some PC4 orthologous proteins. In order to understand the consequences and reveal the molecular details of this substitution we have determined the crystal structures of the PC4 orthologue MoSub1 and a PC4 W89Y mutant in complex with DNA. In the structure of MoSub1-DNA complex, Y74 interacts directly with a single nucleotide of oligo DNA. By comparison, the equivalent residue, W89 in wild type PC4 interacts with two nucleotides and the base of the second nucleotide has distinct orientation relative to that of the first one. A hydrophobic patch around W89 that favours interaction with two nucleotides is not formed in the PC4 W89Y mutant. Therefore, the change of the surface hydrophobicity around residue 89 results in a difference between the modes of DNA interaction. These results indicate that the conserved Y74 in MoSub1 or W89 in PC4, are not only key residues in making specific interactions with DNA but also required to determine the DNA binding mode of PC4 proteins.