Structural convergence endows nuclear transport receptor Kap114p with a transcriptional repressor function toward TATA-binding protein.

The transcription factor TATA-box binding protein (TBP) modulates gene expression in nuclei. This process requires the involvement of nuclear transport receptors, collectively termed karyopherin-ß (Kap-ß) in yeast, and various regulatory factors. In previous studies we showed that Kap114p, a Kap-ß that mediates nuclear import of yeast TBP (yTBP), modulates yTBP-dependent transcription. However, how Kap114p associates with yTBP to exert its multifaceted functions has remained elusive. Here, we employ single-particle cryo-electron microscopy to determine the structure of Kap114p in complex with the core domain of yTBP (yTBPC). Remarkably, Kap114p wraps around the yTBPC N-terminal lobe, revealing a structure resembling transcriptional regulators in complex with TBP, suggesting convergent evolution of the two protein groups for a common function. We further demonstrate that Kap114p sequesters yTBP away from promoters, preventing a collapse of yTBP dynamics required for yeast responses to environmental stress. Hence, we demonstrate that nuclear transport receptors represent critical elements of the transcriptional regulatory network.

Selective Formation of Polyaniline Confined in the Nanopores of a Metal-Organic Framework for Supercapacitors.

In this study, a strategy that can result in the polyaniline (PANI) solely confined within the nanopores of a metal-organic framework (MOF) without forming obvious bulk PANI between MOF crystals is developed. A water-stable zirconium-based MOF, UiO-66-NH2 , is selected as the MOF material. The polymerization of aniline is initiated in the acidic suspension of UiO-66-NH2 nanocrystals in the presence of excess poly(sodium 4-styrenesulfonate) (PSS). Since the pore size of UiO-66-NH2 is too small to enable the insertion of the bulky PSS, the quick formation of pore-confined solid PANI and the slower formation of well dispersed PANI:PSS occur within the MOF crystals and in the bulk solution, respectively. By taking advantage of the resulting homogeneous PANI:PSS polymer solution, the bulk PANI:PSS can be removed from the PANI/UiO-66-NH2 solid by successive washing the sample with fresh acidic solutions through centrifugation. As this is the first time reporting the PANI solely confined in the pores of a MOF, as a demonstration, the obtained PANI/UiO-66-NH2 composite material is applied as the electrode material for supercapacitors. The PANI/UiO-66-NH2 thin films exhibit a pseudocapacitive electrochemical characteristic, and their resulting electrochemical activity and charge-storage capacities are remarkably higher than those of the bulk PANI thin films.

Polyoxometalate adsorbed in a metal-organic framework for electrocatalytic dopamine oxidation.

A redox-active vanadium-based polyoxometalate, V10O28, was post-synthetically immobilized into a water-stable zirconium-based metal-organic framework, NU-902. The adsorbed V10O28 in NU-902 renders charge hopping in the framework in aqueous electrolytes, and the obtained V10O28@NU-902 can be used as a heterogeneous electrocatalyst for electrochemical dopamine sensors.

Diaqua-[3,5-bis-(4-pyrid-yl)-1H-1,2,4-triazole-κN](pyridine-2,6-dicarboxyl-ato-κO,N,O)nickel(II).

In the title compound, [Ni(C(7)H(3)NO(4))(C(12)H(9)N(5))(H(2)O)(2)], the Ni(II) atom is coordinated in a distorted octa-hedral geometry by one N and two O atoms from a pyridine-2,6-dicarboxyl-ate ligand, one N atom from a 3,5-bis-(4-pyrid-yl)-1H-1,2,4-triazole ligand in equatorial positions and two water mol-ecules in axial positions. The crystal packing is consolidated by inter-molecular O-H⋯O, O-H⋯N and N-H⋯O hydrogen bonds.