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Jakob, S.

Publications and source records attributed to Jakob, S..

3 recordsLinked to original sources

Evaluating Seqstant LiveGene Analysis in Real-Time Assessment of Metagenomic Next-Generation Sequencing (mNGS) Data from Respiratory Samples

BackgroundThe detection of pathogens causing infections by conventional diagnostic methods can be challenging and next-generation sequencing (NGS) technology offers a promising alternative method. In this study, we evaluated the performance of real-time metagenomic next-generation sequencing (rt-mNGS) for the detection of pathogens in respiratory samples. MethodWe used rt-mNGS, using the Seqstant LiveGene Analysis platform, on 335 respiratory samples in comparison to conventional culture results. ResultsWe observed an overall good concordance in 71.64% (240/335) of the methods. The rt-mNGS outperformed the gold standard culture in 16.12% (54/335) of the samples, while the culture was superior in detecting the clinically relevant pathogen in 12.24% (41/335) of the samples. The non-inferiority of rt-mNGS was statistically significant ({delta} = 10, = 0.05, 1 - {beta}= 0.8). We also observed that the real-time analysis of NGS data is beneficial in obtaining reliable timely results as the initial report at cycle 46 exhibits a Positive Predictive Value (PPV) of 93.75% at the species-level with a sensitivity of 32.09%. ConclusionOverall, our study showed the non-inferiority of rt-mNGS compared to the standard-of-care microbiology for respiratory samples with statistical significance. Moreover, the rt-mNGS method exhibited superior sensitivity and superior overall performance. It also uniquely detected certain organisms that are typically hard to culture. However, rt-mNGS reported a higher number of false positives and faced limitations in detecting Aspergillus spp. In conclusion, the study highlights the potential of rt-mNGS as a powerful tool in clinical diagnostics of respiratory infections and beyond.

microbiology↗

The virulence regulator VirB from Shigella flexneri uses a CTP-dependent switch mechanism to activate gene expression

The transcriptional antisilencer VirB acts as a master regulator of virulence gene expression in the human pathogen Shigella flexneri. It binds defined sequences (virS) upstream of VirB-dependent promoters and counteracts their silencing by the nucleoid-organizing protein H-NS. However, its precise mode of action remains unclear. Notably, VirB is not a classical transcription factor but related to DNA partitioning proteins of the ParB family, which have recently been recognized as DNA-sliding clamps using CTP binding and hydrolysis to control their DNA entry gate. Here, we show that VirB binds CTP, embraces DNA in a clamp-like fashion upon its CTP-dependent loading at virS sites and slides laterally on DNA after clamp closure. Mutations that prevent CTP binding block the loading of VirB clamps in vitro and the formation of VirB nucleoprotein complexes in vivo. Thus, VirB represents a CTP-dependent molecular switch that uses a loading-and-sliding mechanism to control transcription during bacterial pathogenesis.

microbiology↗

Impact of two neighbouring ribosomal protein clusters on biogenesis factor binding and assembly of yeast late small ribosomal subunit precursors

Many of the small ribosomal subunit proteins are required for the stabilisation of late small ribosomal subunit (SSU) precursors and for final SSU rRNA processing in S. cerevisiae. Among them are ribosomal proteins (r-proteins) which form a protein cluster around rpS0 (uS2) at the \"neck\" of the SSU (S0-cluster) and others forming a nearby protein cluster around rpS3 (uS3) at the SSU \"beak\". Here we applied semi-quantitative proteomics together with complementary biochemical approaches to study how incomplete assembly of these two r-protein clusters affects binding and release of SSU maturation factors and assembly of other r-proteins in late SSU precursors in S. cerevisiae. For each of the two clusters specific impairment of the local r-protein assembly state was observed. Besides, cluster-specific effects on the association of biogenesis factors were detected.\n\nThese suggested a role of S0-cluster formation for the efficient release of the two nuclear export factors Rrp12 and Slx9 from SSU precursors and for the correct incorporation of the late acting biogenesis factor Rio2. Based on our and on previous results we propose the existence of at least two different r-protein assembly checkpoints during late SSU maturation in S. cerevisiae. We discuss in the light of recent SSU precursor structure models how r-protein assembly states might be sensed by biogenesis factors at the S0-cluster checkpoint.

molecular biology↗