The interferon-induced double-stranded RNA-activated protein kinase PKR is the prototype of a class of double-stranded (dsRNA)-binding proteins (DRBPs) which share a dsRNA-binding motif conserved from Drosophila to humans. Here we report the purification of DRBP76, a new human member of this class of proteins. Sequence from the amino terminus of DRBP76 matched that of the M phase-specific protein, MPP4. DRBP76 was also cloned by the yeast two-hybrid screening of a cDNA library using a mutant PKR as bait. Analysis of the cDNA sequence revealed that it is the fulllength version of MPP4, has a bipartite nuclear localization signal, two motifs that can mediate interactions with both dsRNA and PKR, five epitopes for potential M phase-specific phosphorylation, two potential sites for phosphorylation by cyclin-dependent kinases, a RG2 motif present in many RNA-binding proteins and predicts a protein of 76 kDa. DsRNA and PKR interactions of DRBP76 were confirmed by analysis of in vitro translated and purified native proteins. Cellular expression of an epitope-tagged DRBP76 demonstrated its nuclear localization, and its co-immunoprecipitation with PKR demonstrated that the two proteins interact in vivo. Finally, purified DRBP76 was shown to be a substrate of PKR in vitro, indicating that this protein's cellular activities may be regulated by PKR-mediated phosphorylation.

SummaryBackground The 2014 Zaire Ebola virus outbreak highlighted the need for a safe, effective vaccine with a rapid onset of protection. We report the safety and immunogenicity of the recombinant vesicular stomatitis virus-Zaire Ebola virus envelope glycoprotein vaccine (rVSV∆G-ZEBOV-GP) across a 6 log 10 dose range in two sequential cohorts.

high-throughput fabrication of perovskite modules has also been demon strated with simple processes such as blade coating with module efficiency close to 15%. [8] It remains unclear as to whether the perovskite solar cells can operate over 25 years in a real-world environment that is filled with oxygen and moisture, which are their two major stressors. Enhanced encapsulation has clearly shown to elongate the operational lifetime of perovskite solar cells to a much longer duration, indicating that the intrinsic stability of perovskite solar cells may be much longer than expected. [9][10][11] Nevertheless, perovskite solar cells may find their niche applications in space where oxygen or moisture does not exist. For space applications, there are new stressors such as radiation that may impose new threats to the stability of perovskite solar cells, while stability of solar cells under radiation has been rarely studied. The increasing interest in perovskite-based X-ray and gamma-ray detectors warrants an imperative study of the stability of perovskite materials and devices under ionizing radiation. [12,13] Less than a handful of studies have been performed to reveal the effects of proton, electron, and X-ray irradiation on perovskite so far. [14][15][16][17] Miyazawa et al. irradiated perovskite solar cells with 1 MeV electrons and found that the devices retained 93% of their peak performance after irradiation with a fluence of 1 × 10 16 cm −2 . [15] Experiments conducted by Lang et. al. [14] indicated a decrease in short-circuit current density (J SC ) by 20% for perovskite solar cells exposed to a proton dose of 1 × 10 13 p cm −2 . The perovskite self-healed with recovery on fill factor (FF) and open-circuit voltage (V OC ) after the proton irradiation terminated. [16] The effects of soft X-ray exposure on uncovered perovskites were investigated by Motoki et al. who reported that soft X-ray irradiation resulted in the evaporation of perovskite surface with residual elements in the form of crystalline PbI 2 . Apart from above stability studies with different radiation sources, the stability of perovskite device under gamma-ray radiation is also important but remained virtually unexplored. [18] Large amounts of gamma-rays are inevitably produced when the galactic cosmic rays, comprising mainly protons and alpha particles, undergo nuclear interactions with the constituent nuclei of the spacecraft, which poses a challenge to the perovskite materials for their long-term application in space. Moreover, organohalide perovskites also showed great Organohalide metal perovskites have emerged as promising semiconductor materials for use as space solar cells and radiation detectors. However, there is a lack of study of their stability under operational conditions. Here a stability study of perovskite solar cells under gamma-rays and visible light simultaneously is reported. The perovskite active layers are shown to retain 96.8% of their initial power conversion efficiency under continuous irradiation of gamma-rays and light for...

PKR is a cellular serine/threonine kinase that phosphorylates eukaryotic translation initiation factor 2␣ (eIF2␣) to regulate protein synthesis. PKR also plays a role in the regulation of transcription, programmed cell death and the cell cycle, processes which likely involve other substrates. In a yeast two-hybrid screen, we isolated human protein phosphatase 2A (PP2A) regulatory subunit B56␣ as a PKR-interacting protein. The interaction between B56␣ and PKR was confirmed by in vitro binding assays as well as by in vivo coimmunoprecipitation, and this interaction is dependent on the catalytic activity of PKR. Moreover, recombinant B56␣ was efficiently phosphorylated by PKR in vitro and an isoelectric point shift in B56␣ was detected in extracts from cells induced with the PKR activator pIC. An in vitro dephosphorylation assay showed that when B56␣ was phosphorylated by PKR, the activity of PP2A trimeric holoenzyme was increased. A functional interaction between B56␣ and PKR was observed in cotransfection assays, where a B56␣-mediated increase in luciferase expression was inhibited by cotransfection with wild-type PKR. This is likely due to a decreased level of eIF4E phosphorylation caused by an increase in PP2A activity following PKR phosphorylation of B56␣. Taken together, our data indicate that PKR can modulate PP2A activity by phosphorylating B56␣ to regulate cellular activities.