Negative-strand RNA viruses condense their genome into a helical nucleoprotein-RNA complex, the nucleocapsid, which is packed into virions and serves as a template for the RNA-dependent RNA polymerase complex. The crystal structure of a recombinant rabies virus nucleoprotein-RNA complex, organized in an undecameric ring, has been determined at 3.5 angstrom resolution. Polymerization of the nucleoprotein is achieved by domain exchange between protomers, with flexible hinges allowing nucleocapsid formation. The two core domains of the nucleoprotein clamp around the RNA at their interface and shield it from the environment. RNA sequestering by nucleoproteins is likely a common mechanism used by negative-strand RNA viruses to protect their genomes from the innate immune response directed against viral RNA in human host cells at certain stages of an infectious cycle.

Transcription of the highly pathogenic Ebola virus depends on VP30, a nucleocapsid-associated Ebola virus-specific transcription factor. The transcription activator VP30 was shown to play an essential role in Ebola virus replication, most likely by stabilizing nascent mRNA. Here we present the crystal structure of the C-terminal domain (CTD) of VP30 (VP30 _CTD ) at 2.0-Å resolution. VP30 _CTD folds independently into a dimeric helical assembly. The VP30 _CTD dimers assemble into hexamers that are present in virions, by an oligomerization domain located in the N terminus of VP30. Mutagenesis of conserved charged amino acids on VP30 _CTD revealed that two regions, namely a basic cluster around Lys-180 and Glu-197, are required for nucleocapsid interaction. However, only mutagenesis of the basic cluster was shown to impair transcription activation, suggesting that both processes are regulated independently. The structure and the mutagenesis results reveal a potential pocket for small-molecule inhibitors that might prevent VP30 activity and thus virus propagation as it has been shown previously by peptides, which interfere with VP30 homooligomerization.

Unsymmetrical Schiff base obtained by the condensation reaction of (1R,2R)(−)cyclohexanediamine with 2-hydroxybenzaldehyde and 2-hydroxynaphthaldehyde was used as a ligand for copper(II) and nickel(II). The ligand and complexes were characterized by circular dichroism (CD), UV-VIS, fluorescence, IR and ¹H (NOE diff), NOESY and ¹³C NMR (ligand) spectra. The X-ray crystal structures solved for (1R,2R)(−)chxn(salH)(naftalH) and Cu(II)(1R,2R)(−)chxn(sal)(naftal) revealed tetrahedral distortion of coordination sphere in the solid phase. The [Cu(1R,2R)(−)chxn(sal)(naftal)]·0.5EtOH·1.25H₂O complex crystallized in the monoclinic chiral C2 space group with two molecules in the asymmetric unit as well as disordered ethanol and water molecules. For both molecules Cu(II) ions were found in square-planar environments and adopts conformation described as “semi-open armed”, because of distinctly oriented arms according to cyclohexane ring defined by three torsion angles. The thin layers of the ligands, copper(II) and nickel(II) complexes were deposited on Si(111) by a spin coating method and characterized with scanning electron microscopy SEM/EDS and fluorescence spectra. The ligand layers exhibit the most intensive fluorescence band at 498 nm, which can be assigned to emission transition π* → n of Schiff base ligand. For copper(II) layers the most intensive band from intraligand transition at 550 nm was observed. The highest intensity band was registered for the layer obtained when rotation speed was 1000 rpm and time 20 s. The nickel(II) complex layers fluorescence spectra exhibit an intensive band at 564 nm. The emission maxima of the copper(II) and nickel(II) complexes are shifted towards longer wavelength in comparison to the free ligand layers. CD spectra of the complexes in solution are characteristic for tetrahedral planar distortion of the chelate ring. The ¹H NMR NOE diff were measured and the position of the nearest hydrogen atoms in the cyclohexane and aromatic rings were discussed, suggesting the tetrahedral distortion of the central ion of the coordination sphere in solution.

Two ruthenium(III) complexes composed of 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) ligands were prepared and structurally characterized by X-ray crystallography, IR, UV-Vis, EPR spectroscopies and cyclic voltammetry (CV). The crystal structures of trans-[RuCl₃(H₂O)(dbtp)₂] 1 and mer-[RuCl₃(dbtp)₃]·0.815OCMe₂2 showed slightly distorted octahedral geometries with two 1 or three 2 monodentate dbtp ligands bound in a head-to-head orientation. In both complexes, the heterocyclic dbtp ligands were bound to the ruthenium(III) ion through the N3 nitrogen atom. A cytotoxicity assay of both ruthenium(III) compounds against two human cell lines (A549 – non-small cell lung carcinoma and T47D – breast carcinoma) was performed. The ruthenium(III) complexes showed excellent cytotoxicity with IC₅₀ values in the range of 0.02–2.4 μM against both cancer cell lines. In addition, the in vitro cytotoxic values of the ruthenium(III) compounds were 35-times for 1 and 172-times for 2 higher against T47D than the clinically used antitumor drug cisplatin.