Project description:A total of 25 modifications were mapped to 16S and 23S RNA in B. subtilis ribosome, however most of the genes responsible for these modification sites remain unknown. In this work, bottom-up oligonucleotide LC-MS/MS was used to detect rRNA modifications in five single gene knock-out strains: yydA, yhcT, yjbO, ylyB, yqxC. By comparing oligonucleotide modification states between the background 168 strain (annotated as WT) and the mutants: ylyB was confirmed to be a pseudouridine synthase at positions 1940, 1944, 1946 of 23S; yydA is a N3-pseudouridine methyltransferase at 1944 of 23S; and yqxC is a dual 2’O-cytidine methyltransferase at 1417 of 16S and 1949 of 23S. Deletion of yhcT or yjbO does not change rRNA modification pattern.
Project description:Post-transcriptional modifications are added to ribosomal RNAs (rRNAs) to govern ribosome biogenesis and to fine-tune protein biosynthesis. RlhA, a dedicated modification enzyme, adds a unique 5-hydroxycytidine (ho5C) at 23S rRNA position 2501 in E. coli and related bacteria. However, the molecular and biological functions as well as the regulation of ho5C2501 remain unclear. We conducted extensive growth curves with the modification-deficient ∆rlhA strain and quantified the extent of the modification during different conditions by mass spectrometry and reverse transcription. The levels of ho5C2501 in E. coli ribosomes turned out to be highly dynamic and growth phase-dependent, with the most effective hydroxylation yields observed in the stationary phase. We demonstrated a direct effect of ho5C2501 on translation efficiencies in vitro and in vivo. High ho5C2501 levels reduced protein biosynthesis which however turned out to be beneficial for E. coli for adapting to oxidative stress. This functional advantage was small under optimal conditions or during heat or cold shock, but becomes pronounced in the presence of hydrogen peroxide. Taken together, these data provided first functional insights into the role of this unique 23S rRNA modification for ribosome functions and bacterial growth under oxidative stress.
Project description:The use of antiretroviral therapy (ART) as pre-exposure prophylaxis (PrEP) is an effective strategy for preventing HIV acquisition. The cellular consequences of PrEP exposure, however, have not been sufficiently explored to determine potential effects on health in individuals without HIV. Peripheral blood mononuclear cells (PBMCs) from people without HIV were exposed to tenofovir disoproxil fumarate (TDF) or emtricitabine (FTC) overnight. Mitochondrial mass and function were measured by flow cytometry and Agilent XFp analyzer. Monocyte-derived macrophages (MDMs) were differentiated in 20% autologous serum for 5 days in the presence or absence of TDF or FTC, and surface markers, lipid uptake, and efferocytosis were measured by flow cytometry. MDM gene expression was measured using RNAseq. Serum lipids were measured using mass spectrometry. PBMCs exposed to TDF or FTC had decreased maximal oxygen consumption rate (OCR) and reduced mitochondrial mass. Exposure to PrEP also increased reactive oxygen species (ROS) production from monocyte subsets. Compared to MDMs cultured in medium alone, cells differentiated in the presence of TDF (829 genes) or FTC (888) genes had significant changes in gene expression. Further, PrEP-exposed MDMs had decreased mitochondrial mass, and displayed increased lipid uptake and reduced efferocytosis. Plasma biomarkers and lipid levels were also altered in vivo in individuals receiving a PrEP regimen. Exposure of leukocytes to TDF or FTC resulted in decreased mitochondrial function, and altered functional and transcriptional profiles. These findings may have important implications for the metabolic and immunologic consequences of PrEP in populations at risk for HIV acquisition.
Project description:We performed miRNA microarray profiling on samples prepared from two different cell lines by three widely-used total RNA sample prep methods.
Project description:Human skin microbiome dysbiosis can have clinical consequences. Characterizing taxonomic composition of bacterial communities associated with skin disorders is important for dermatological advancement in both diagnosis and novel treatments. This study aims to analyze and improve the accuracy of taxonomic classification of skin bacteria with MinION™ nanopore sequencing using a defined skin mock community and a skin microbiome sample. We compared the Oxford Nanopore Technologies recommended procedures and concluded that their protocols highly bias the relative abundance of certain skin microbiome genera, most notably a large overrepresentation of Staphylococcus and underrepresentation of Cutibacterium and Corynebacterium. We demonstrated that changes in the amplification protocols improved the accuracy of the taxonomic classification for these three main skin bacterial genera. This study shows that MinION™ nanopore could be an efficient technology for full-length 16S rRNA sequencing; however, the analytical advantage is strongly influenced by the methodologies. The suggested alternatives in the sample processing improved characterization of a complex skin microbiome community using MinION™ nanopore sequencing.
Project description:The 120-nt long 5S rRNA, is an indispensable component of cytoplasmic ribosomes in all living organisms. The functions of 5S rRNA and the reasons for its evolutionary preservation as an independent molecule remain unclear. Here we used ribosome engineering to investigate whether maintaining 5S rRNA as an independent molecule is critical for ribosome function and cell survival. By fusing circularly permutated 5S rRNA (cp5S) with 23S rRNA and deleting all wild type 5S rRNA genes, we generated an Escherichia coli strain completely devoid of free 5S rRNA. Viability of the engineered cells demonstrates that autonomous 5S rRNA is not required for cell growth at 37°C and is unlikely to have essential functions outside the ribosome. The fully-assembled ribosomes carrying 23S-cp5S hybrid rRNA and lacking free 5S rRNA are highly active in translation. However, the engineered cells accumulate aberrant 50S subunits that are unable to form stable 70S ribosomes. Cryo-EM analysis revealed a dramatically malformed peptidyl transferase center in the misassembled 50S subunits. The results of our experiments argue that the key evolutionary force preserving the autonomous nature of the smallest rRNA is its role in ribosome biogenesis.