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Abstract Dimethyl sulfoxide (DMSO) is a widely used solvent in drug research. However, recent studies indicate that even at low concentration DMSO might cause structural changes of proteins and RNA. The pyrazolopyrimidine antiviral OBR-5-340 dissolved in DMSO inhibits rhinovirus-B5 infection yet is inactive against RV-A89. This is consistent with our structural observation that OBR-5-340 is only visible at the pocket factor site in rhinovirus-B5 and not in RV-A89, where the hydrophobic pocket is collapsed. Here, we analyze the impact of DMSO in RV-A89 by high-resolution cryo-electron microscopy. Our 1.76 Å cryo-EM reconstruction of RV-A89 in plain buffer, without DMSO, reveals that the pocket-factor binding site is occupied by myristate and that the previously observed local heterogeneity at protein–RNA interfaces is absent. These findings suggest that DMSO elutes the pocket factor, leading to a collapse of the hydrophobic pocket of RV-A89. Consequently, the conformational heterogeneity observed at the RNA-protein interface in the presence of DMSO likely results from increased capsid flexibility due to the absence of the pocket factor and DMSO-induced affinity modifications. This local asymmetry may promote a directional release of the RNA genome during infection.

Virulent type III secretion systems (T3SSs) or injectisomes enable pathogenic bacteria to inject effector proteins directly into the host cell cytoplasm. Structures of a needle complex engaged with the effector protein reveal the complete secretion channel and provide insights into the mechanism of substrate translocation through T3SSs.

In this study, the diversity of bphA genes was assessed in a 13C-enriched metagenome upon stable isotope probing (SIP) of microbial populations in legacy PCB-contaminated soil with 13C-biphenyl (BP). In total, 13 bphA sequence variants (SVs) were identified in the final amplicon dataset. Of these, one SV comprised 59% of all sequences, and when it was translated into a protein sequence, it exhibited 87, 77.4, and 76.7% identity to its homologs from Pseudomonas furukawaii KF707, Cupriavidus sp. WS, and Pseudomonas alcaliphila B-367, respectively. This same BphA sequence also contained unusual amino acid residues, Alanine, Valine, and Serine in region III, which had been reported to be crucial for the substrate specificity of the corresponding biphenyl dioxygenase (BPDO), and was accordingly designated BphA_AVS. The DNA locus of 18 kbp containing the BphA_AVS-coding sequence retrieved from the metagenome was comprised of 16 ORFs and was most likely borne by Paraburkholderia sp. The BPDO corresponding to bphAE_AVS was cloned and heterologously expressed in E. coli, and its substrate specificity toward PCBs and a spectrum of flavonoids was assessed. Although depleting a rather narrow spectrum of PCB congeners, the efficient transformation of flavone and flavanone was demonstrated through dihydroxylation of the B-ring of the molecules. The homology-based functional assignment of the putative proteins encoded by the rest of ORFs in the AVS region suggests their potential involvement in the transformation of aromatic compounds, such as flavonoids. In conclusion, this study contributes to the body of information on the involvement of soil-borne BPDOs in the metabolism of flavonoid compounds, and our paper provides a more advanced context for understanding the interactions between plants, microbes and anthropogenic compounds in the soil.

Gram-negative pathogens evolved a syringe-like nanomachine, termed type 3 secretion system, to deliver protein effectors into the cytoplasm of host cells. An essential component of this system is a long helical needle filament that protrudes from the bacterial surface and connects the cytoplasms of the bacterium and the eukaryotic cell. Previous structural research was predominantly focused on reconstituted type 3 needle filaments, which lacked the biological context. In this work we introduce a facile procedure to obtain high-resolution cryo-EM structure of needle filaments attached to the basal body of type 3 secretion systems. We validate our approach by solving the structure of Salmonella PrgI filament and demonstrate its utility by obtaining the first high-resolution cryo-EM reconstruction of Shigella MxiH filament. Our work paves the way to systematic structural characterization of attached type 3 needle filaments in the context of mutagenesis studies, protein structural evolution and drug development.

Bacteria were identified associated with biodegradation of aromatic pollutants biphenyl, benzoate, and naphthalene in a long-term polychlorinated biphenyl- and polyaromatic hydrocarbon-contaminated soil. In order to avoid biases of culture-based approaches, stable isotope probing was applied in combination with sequence analysis of 16 S rRNA gene pyrotags amplified from (13)C-enriched DNA fractions. Special attention was paid to pyrosequencing data analysis in order to eliminate the errors caused by either generation of amplicons (random errors caused by DNA polymerase, formation of chimeric sequences) or sequencing itself. Therefore, sample DNA was amplified, sequenced, and analyzed along with the DNA of a mock community constructed out of 8 bacterial strains. This warranted that appropriate tools and parameters were chosen for sequence data processing. (13)C-labeled metagenomes isolated after the incubation of soil samples with all three studied aromatics were largely dominated by Proteobacteria, namely sequences clustering with the genera Rhodanobacter Burkholderia, Pandoraea, Dyella as well as some Rudaea- and Skermanella-related ones. Pseudomonads were mostly labeled by (13)C from naphthalene and benzoate. The results of this study show that many biphenyl/benzoate-assimilating bacteria derive carbon also from naphthalene, pointing out broader biodegradation abilities of some soil microbiota. The results also demonstrate that, in addition to traditionally isolated genera of degradative bacteria, yet-to-be cultured bacteria are important players in bioremediation. Overall, the study contributes to our understanding of biodegradation processes in contaminated soil. At the same time our results show the importance of sequencing and analyzing a mock community in order to more correctly process and analyze sequence data.

The coronavirus disease (COVID-19) has significantly affected society, especially healthcare systems worldwide. The aim of this retrospective study is to evaluate the impact of the COVID-19 pandemic on orthopaedic and trauma healthcare at the largest university hospital in the Czech Republic. The evaluated periods were in accordance with three waves of the disease and three respective lockdowns. To correlate the results, we evaluated the number of patients (inpatients and outpatients) treated in the same period in the last 3 years before the pandemic. The number of orthopaedic outpatients during the lockdown period decreased by 54.12% (p = 0.002), 42.88% (p

The coronavirus disease (COVID-19) has significantly affected society, especially healthcare systems worldwide. The aim of this retrospective study is to evaluate the impact of the COVID-19 pandemic on orthopaedic and trauma healthcare at the largest university hospital in the Czech Republic. The evaluated periods were in accordance with three waves of the disease and three respective lockdowns. To correlate the results, we evaluated the number of patients (inpatients and outpatients) treated in the same period in the last 3 years before the pandemic. The number of orthopaedic outpatients during the lockdown period decreased by 54.12% (p = 0.002), 42.88% (p

Autor reaguje na publikaci archeologického výzkumu na tabulové hoře Úhošť z pera Zdeňka Smrže. Diskusí procházejí přírodní parametry, otázka opevnění a umělého pahorku. Příspěvek zařazuje Úhošť do kontextu dalších tabulových hor ve střední Evropě, které vydaly doklady svého využití od doby bronzové do středověku.