Riding in silence: a little snowboarding, a lot of small RNAs

The recent symposium, RNA silencing: Mechanism, Biology and Applications, organized by Phillip D. Zamore (University of Massachusetts Medical School) and Beverly Davidson (University of Iowa), and held in Keystone, Colorado, brought together scientists working on diverse aspects of RNA silencing, a field that comprises a multitude of gene regulatory pathways guided by microRNAs, small interfering RNAs and PIWI-interacting RNAs

Multistep Engineering of Pyrrolysyl-tRNA Synthetase to Genetically Encode Nɛ-(o-Azidobenzyloxycarbonyl) lysine for Site-Specific Protein Modification

SummaryPyrrolysyl-tRNA synthetase (PylRS) esterifies pyrrolysine to tRNAPyl. In this study, Nɛ-(tert-butyloxycarbonyl)-L-lysine (BocLys) and Nɛ-allyloxycarbonyl-L-lysine (AlocLys) were esterified to tRNAPyl by PylRS. Crystal structures of a PylRS catalytic fragment complexed with BocLys and an ATP analog and with AlocLys-AMP revealed that PylRS requires an Nɛ-carbonyl group bearing a substituent with a certain size. A PylRS(Y384F) mutant obtained by random screening exhibited higher in vitro aminoacylation and in vivo amber suppression activities with BocLys, AlocLys, and pyrrolysine than those of the wild-type PylRS. Furthermore, the structure-based Y306A mutation of PylRS drastically increased the in vitro aminoacylation activity for Nɛ-benzyloxycarbonyl-L-lysine (ZLys). A PylRS with both the Y306A and Y384F mutations enabled the large-scale preparation (>10 mg per liter medium) of proteins site-specifically containing Nɛ-(o-azidobenzyloxycarbonyl)-L-lysine (AzZLys). The AzZLys-containing protein was labeled with a fluorescent probe, by Staudinger ligation

Exome-wide association study to identify rare variants influencing COVID-19 outcomes : Results from the Host Genetics Initiative

Publisher Copyright: Copyright: © 2022 Butler-Laporte et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Host genetics is a key determinant of COVID-19 outcomes. Previously, the COVID-19 Host Genetics Initiative genome-wide association study used common variants to identify multiple loci associated with COVID-19 outcomes. However, variants with the largest impact on COVID-19 outcomes are expected to be rare in the population. Hence, studying rare variants may provide additional insights into disease susceptibility and pathogenesis, thereby informing therapeutics development. Here, we combined whole-exome and whole-genome sequencing from 21 cohorts across 12 countries and performed rare variant exome-wide burden analyses for COVID-19 outcomes. In an analysis of 5,085 severe disease cases and 571,737 controls, we observed that carrying a rare deleterious variant in the SARS-CoV-2 sensor toll-like receptor TLR7 (on chromosome X) was associated with a 5.3-fold increase in severe disease (95% CI: 2.75–10.05, p = 5.41x10-7). This association was consistent across sexes. These results further support TLR7 as a genetic determinant of severe disease and suggest that larger studies on rare variants influencing COVID-19 outcomes could provide additional insights.Peer reviewe

The whole blood transcriptional regulation landscape in 465 COVID-19 infected samples from Japan COVID-19 Task Force

「コロナ制圧タスクフォース」COVID-19患者由来の血液細胞における遺伝子発現の網羅的解析 --重症度に応じた遺伝子発現の変化には、ヒトゲノム配列の個人差が影響する--. 京都大学プレスリリース. 2022-08-23.Coronavirus disease 2019 (COVID-19) is a recently-emerged infectious disease that has caused millions of deaths, where comprehensive understanding of disease mechanisms is still unestablished. In particular, studies of gene expression dynamics and regulation landscape in COVID-19 infected individuals are limited. Here, we report on a thorough analysis of whole blood RNA-seq data from 465 genotyped samples from the Japan COVID-19 Task Force, including 359 severe and 106 non-severe COVID-19 cases. We discover 1169 putative causal expression quantitative trait loci (eQTLs) including 34 possible colocalizations with biobank fine-mapping results of hematopoietic traits in a Japanese population, 1549 putative causal splice QTLs (sQTLs; e.g. two independent sQTLs at TOR1AIP1), as well as biologically interpretable trans-eQTL examples (e.g., REST and STING1), all fine-mapped at single variant resolution. We perform differential gene expression analysis to elucidate 198 genes with increased expression in severe COVID-19 cases and enriched for innate immune-related functions. Finally, we evaluate the limited but non-zero effect of COVID-19 phenotype on eQTL discovery, and highlight the presence of COVID-19 severity-interaction eQTLs (ieQTLs; e.g., CLEC4C and MYBL2). Our study provides a comprehensive catalog of whole blood regulatory variants in Japanese, as well as a reference for transcriptional landscapes in response to COVID-19 infection

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target

Crystallization and preliminary X-ray crystallographic study of alanyl-tRNA synthetase from the archaeon Archaeoglobus fulgidus

The N- and C-terminal fragments of alanyl-tRNA synthetase from the archaeon A. fulgidus have been crystallized

dsRNA with 5′ overhangs contributes to endogenous and antiviral RNA silencing pathways in plants

In plants, SGS3 and RNA-dependent RNA polymerase 6 (RDR6) are required to convert single- to double-stranded RNA (dsRNA) in the innate RNAi-based antiviral response and to produce both exogenous and endogenous short-interfering RNAs. Although a role for RDR6-catalysed RNA-dependent RNA polymerisation in these processes seems clear, the function of SGS3 is unknown. Here, we show that SGS3 is a dsRNA-binding protein with unexpected substrate selectivity favouring 5'-overhang-containing dsRNA. The conserved XS and coiled-coil domains are responsible for RNA-binding activity. Furthermore, we find that the V2 protein from tomato yellow leaf curl virus, which suppresses the RNAi-based host immune response, is a dsRNA-binding protein with similar specificity to SGS3. In competition-binding experiments, V2 outcompetes SGS3 for substrate dsRNA recognition, whereas a V2 point mutant lacking the suppressor function in vivo cannot efficiently overcome SGS3 binding. These findings suggest that SGS3 recognition of dsRNA containing a 5' overhang is required for subsequent steps in RNA-mediated gene silencing in plants, and that V2 functions as a viral suppressor by preventing SGS3 from accessing substrate RNAs