Open Access

NAD is a coenzyme central to metabolism that was also found to serve as a 5’-terminal cap of bacterial and eukaryotic RNA species. The presence and functionality of NAD-capped RNAs (NAD-RNAs) in the archaeal domain remain to be characterized in detail. Here, by combining LC-MS and NAD captureSeq methodology, we quantified the total levels of NAD-RNAs and determined the identity of NAD-RNAs in the two model archaea, Sulfolobus acidocaldarius and Haloferax volcanii. A complementary differential RNA-Seq (dRNA-Seq) analysis revealed that NAD transcription start sites (NAD-TSS) correlate with well-defined promoter regions and often overlap with primary transcription start sites (pTSS). The population of NAD-RNAs in the two archaeal organisms shows clear differences, with S. acidocaldarius possessing more capped small non-coding RNAs (sncRNAs) and leader sequences. The NAD-cap did not prevent 5’→3’ exonucleolytic activity by the RNase Saci-aCPSF2. To investigate enzymes that facilitate the removal of the NAD-cap, four Nudix proteins of S. acidocaldarius were screened. None of the recombinant proteins showed NAD decapping activity. Instead, the Nudix protein Saci_NudT5 showed activity after incubating NAD-RNAs at elevated temperatures. Hyperthermophilic environments promote the thermal degradation of NAD into the toxic product ADPR. Incorporating NAD into RNAs and the regulation of ADPR-RNA decapping by Saci_NudT5 is proposed to provide additional layers of maintaining stable NAD levels in archaeal cells. Importance: This study reports the first characterization of 5’-terminally modified RNA molecules in Archaea and establishes that NAD-RNA modifications, previously only identified in the other two domains of life, are also prevalent in the archaeal model organisms Sulfolobus acidocaldarius and Haloferax volcanii. We screened for NUDIX hydrolases that could remove the NAD-RNA cap and showed that none of these enzymes removed NAD modifications, but we discovered an enzyme that hydrolyzes ADPR-RNA. We propose that these activities influence the stabilization of NAD and its thermal degradation to potentially toxic ADPR products at elevated growth temperatures.

New rules to tackle shadow banking, improve consumer protection, and recommendations for addressing nature-related financial risks.

We report a joint experimental and theoretical study of the differential photoelectron circular dichroism (PECD) in inner-shell photoionization of uniaxially oriented trifluoromethyloxirane. By adjusting the photon energy of the circularly polarized synchrotron radiation, we address 1s-photoionization of the oxygen, different carbon, and all fluorine atoms. The photon energies were chosen such that in all cases electrons with a similar kinetic energy of about 11 eV are emitted. Employing coincident detection of electrons and fragment ions, we concentrate on identical molecular fragmentation channels for all of the electron-emitter scenarios. Thereby, we systematically examine the influence of the emission site of the photoelectron wave on the differential PECD. We observe large differences in the PECD signals. The present experimental results are supported by corresponding relaxed-core Hartree–Fock calculations.

Sphingolipids are not only structural components of cell membranes but can also act as signalling molecules in different pathways. Sphingolipid precursors, Ceramides (Cer), are synthesized de novo by six different synthases (CerS1-6) which generate Cer of different chain lengths. Cer can be further synthesized to glycosphingolipids and sphingomyelin. Cell membrane parts that are enriched in glycosphingolipids are so-called lipid rafts and can function as signalling platforms for different receptors, such like the T cell receptor (TCR). CD4+ T cells play a crucial role in the development of ulcerative colitis, a chronic inflammatory disease of the colon. As CerS3 expression was increased in the white blood cells of human colitis patients, the role of CerS3 in the TCR signalling and colitis was investigated in this dissertation. By lenti-viral transduction of a CerS3-shRNA into a CD4+ Jurkat cell line, it was shown that CerS3 has an impact on activated T cells. A decrease of different sphingolipids after T cell activation via CD2/3/28 activation beads and IL2 treatment was observed that was accompanied by an inhibition of Zap70 phosphorylation, an important protein of the TCR signalling. The impaired TCR signalling led to a diminished NFAT1 translocation into the nucleus which subsequently led to a reduced NFAT1- dependent TNFα release. Downregulation of CerS3 in primary CD4+ T cells, obtained from the blood of healthy volunteers, also showed a reduced release of pro-inflammatory cytokines after activation. This dissertation demonstrates a pivotal role for CerS3 in T cell function and highlights CerS3 as potential new target for T cell driven colitis.

A systematic study of HBT radii of pions, produced in heavy ion collisions in the intermediate energy regime (SPS), from an integrated (3+1)d Boltzmann+hydrodynamics approach is presented. The calculations in this hybrid approach, incorporating an hydrodynamic stage into the Ultra-relativistic Quantum Molecular Dynamics transport model, allow for a comparison of different equations of state retaining the same initial conditions and final freeze-out. The results are also compared to the pure cascade transport model calculations in the context of the available data. Furthermore, the effect of different treatments of the hydrodynamic freeze-out procedure on the HBT radii are investigated. It is found that the HBT radii are essentially insensitive to the details of the freeze-out prescription as long as the final hadronic interactions in the cascade are taken into account. The HBT radii RL and RO and the RO/RS ratio are sensitive to the EoS that is employed during the hydrodynamic evolution. We conclude that the increased lifetime in case of a phase transition to a QGP (via a Bag Model equation of state) is not supported by the available data.