Reston viruses are the only Ebolaviruses that are not pathogenic in humans. We analyzed 196 Ebolavirus genomes and identified specificity determining positions (SDPs) in all nine Ebolavirus proteins that distinguish Reston viruses from the four human pathogenic Ebolaviruses. A subset of these SDPs will explain the differences in human pathogenicity between Reston and the other four ebolavirus species. Structural analysis was performed to identify those SDPs that are likely to have a functional effect. This analysis revealed novel functional insights in particular for Ebolavirus proteins VP40 and VP24. The VP40 SDP P85T interferes with VP40 function by altering octamer formation. The VP40 SDP Q245P affects the structure and hydrophobic core of the protein and consequently protein function. Three VP24 SDPs (T131S, M136L, Q139R) are likely to impair VP24 binding to human karyopherin alpha5 (KPNA5) and therefore inhibition of interferon signaling. Since VP24 is critical for Ebolavirus adaptation to novel hosts, and only a few SDPs distinguish Reston virus VP24 from VP24 of other Ebolaviruses, human pathogenic Reston viruses may emerge. This is of concern since Reston viruses circulate in domestic pigs and can infect humans, possibly via airborne transmission.

Trp(redBODIPY) is the first red-emitting Trp-based amino acid for the preparation of fluorogenic peptides with retention of target binding affinity.

Imidazole-based compounds previously synthesized in our laboratory were selected and reconsidered as inhibitors of heme oxygenase-1 obtained from the microsomal fractions of rat spleens. Most of tested compounds were good inhibitors with IC 50 values in the low micromolar range. Compounds were also assayed on membrane-free fulllength recombinant human heme oxygenase-1; all tested compounds were unable to interact with human heme oxygenase-1 at 100 lM concentrations with the exception of compounds 11 and 13 that inhibited the enzyme of 54% and 20%, respectively. The binding of the most active compound 11 with heme or heme-conjugated human heme oxygenase-1 was also examined by spectral analyses. When heme was not conjugated to human heme oxygenase-1, compound 11 caused changes in the heme spectrum only at concentration 50-fold (100 lM) higher than that required to inhibit rat heme oxygenase-1; when heme was conjugated to human heme oxygenase-1, compound 11 was able to form a heme-compound 11 complex also at low micromolar concentrations. To obtain information on the binding mode of the tested compounds with enzyme, docking studies and pharmacophore analysis were performed. Template docking results were in agreement with experimental inhibition data and with a structure-based pharmacophoric model. These data may be exploitable to design new OH-1 inhibitors.Key words: docking studies, enzymatic and spectral analyses, HO-1 inhibitors, imidazole-based compounds, pharmacophoric model Heme oxygenase (HO) is a microsomal enzyme catalyzing the first, rate-limiting step in degradation of heme, yielding equimolar quantities of carbon monoxide (CO), Fe 2+ , and biliverdin (1). Finally, biliverdin is converted by biliverdin reductase to bilirubin (2), which can be oxidized by cytochrome P450 (CYP450) enzymes (3). Three distinct mammalian HO isoforms (HO-1, HO-2, and HO-3) have been identified, which are the products of different genes (4). HO-1, the inducible 32-kDa isoform, is highly expressed in the liver and spleen, but can be also detected in many other tissues. HO-2 is a constitutively expressed 36-kDa protein, present in high levels in the brain, testes, or endothelial cells. HO-3 was postulated as a 33-kDa protein expressed in different organs, very similar to HO-2, but with much lower catalytic activity (5). The HO system has been demonstrated to have a variety of cellular regulatory actions including anti-inflammatory, anti-apoptotic, anti-proliferative, and vasodilator effects, owing to contributing and complementary effects of each of the metabolites produced (6-9).Interestingly, expression of HO-1 is usually increased in tumors, compared with surrounding healthy tissues (10-13). It has been reported that the growth of a number of tumors is dependent on HO-1 activity (14). These results support the idea that HO-1 may be a potential target in antitumor therapy. Thus, pharmacologic inhibition of HO-1 has been suggested as a new therapeutic option and potential sensitizer to chemotherapy, radiotherapy, or photodynamic...

Unravelling the genotype–phenotype relationship in humans remains a challenging task in genomics studies. Recent advances in sequencing technologies mean there are now thousands of sequenced human genomes, revealing millions of single nucleotide variants (SNVs). For non-synonymous SNVs present in proteins the difficulties of the problem lie in first identifying those nsSNVs that result in a functional change in the protein among the many non-functional variants and in turn linking this functional change to phenotype. Here we present VarMod (Variant Modeller) a method that utilises both protein sequence and structural features to predict nsSNVs that alter protein function. VarMod develops recent observations that functional nsSNVs are enriched at protein–protein interfaces and protein–ligand binding sites and uses these characteristics to make predictions. In benchmarking on a set of nearly 3000 nsSNVs VarMod performance is comparable to an existing state of the art method. The VarMod web server provides extensive resources to investigate the sequence and structural features associated with the predictions including visualisation of protein models and complexes via an interactive JSmol molecular viewer. VarMod is available for use at http://www.wasslab.org/varmod.

BackgroundEbolaviruses have been known to cause deadly disease in humans for 40 years and have recently been demonstrated in West Africa to be able to cause large outbreaks. Four Ebolavirus species cause severe disease associated with high mortality in humans. Reston viruses are the only Ebolaviruses that do not cause disease in humans. Conserved amino acid changes in the Reston virus protein VP24 compared to VP24 of other Ebolaviruses have been suggested to alter VP24 binding to host cell karyopherins resulting in impaired inhibition of interferon signalling, which may explain the difference in human pathogenicity. Here we used protein structural analysis and molecular dynamics to further elucidate the interaction between VP24 and KPNA5.ResultsAs a control experiment, we compared the interaction of wild-type and R137A-mutant (known to affect KPNA5 binding) Ebola virus VP24 with KPNA5. Results confirmed that the R137A mutation weakens direct VP24-KPNA5 binding and enables water molecules to penetrate at the interface. Similarly, Reston virus VP24 displayed a weaker interaction with KPNA5 than Ebola virus VP24, which is likely to reduce the ability of Reston virus VP24 to prevent host cell interferon signalling.ConclusionOur results provide novel molecular detail on the interaction of Reston virus VP24 and Ebola virus VP24 with human KPNA5. The results indicate a weaker interaction of Reston virus VP24 with KPNA5 than Ebola virus VP24, which is probably associated with a decreased ability to interfere with the host cell interferon response. Hence, our study provides further evidence that VP24 is a key player in determining Ebolavirus pathogenicity.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-017-3912-2) contains supplementary material, which is available to authorized users.