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  1. Article ; Online: Host-specific asymmetric accumulation of mutation types reveals that the origin of SARS-CoV-2 is consistent with a natural process

    Ke-Jia Shan / Changshuo Wei / Yu Wang / Qing Huan / Wenfeng Qian

    The Innovation, Vol 2, Iss 4, Pp 100159- (2021)

    2021  

    Abstract: The capacity of RNA viruses to adapt to new hosts and rapidly escape the host immune system is largely attributable to de novo genetic diversity that emerges through mutations in RNA. Although the molecular spectrum of de novo mutations—the relative ... ...

    Abstract The capacity of RNA viruses to adapt to new hosts and rapidly escape the host immune system is largely attributable to de novo genetic diversity that emerges through mutations in RNA. Although the molecular spectrum of de novo mutations—the relative rates at which various base substitutions occur—are widely recognized as informative toward understanding the evolution of a viral genome, little attention has been paid to the possibility of using molecular spectra to infer the host origins of a virus. Here, we characterize the molecular spectrum of de novo mutations for SARS-CoV-2 from transcriptomic data obtained from virus-infected cell lines, enabled by the use of sporadic junctions formed during discontinuous transcription as molecular barcodes. We find that de novo mutations are generated in a replication-independent manner, typically on the genomic strand, and highly dependent on mutagenic mechanisms specific to the host cellular environment. De novo mutations will then strongly influence the types of base substitutions accumulated during SARS-CoV-2 evolution, in an asymmetric manner favoring specific mutation types. Consequently, similarities between the mutation spectra of SARS-CoV-2 and the bat coronavirus RaTG13, which have accumulated since their divergence strongly suggest that SARS-CoV-2 evolved in a host cellular environment highly similar to that of bats before its zoonotic transfer into humans. Collectively, our findings provide data-driven support for the natural origin of SARS-CoV-2. Public summary: • The asymmetric de novo mutations in SARS-CoV-2 are induced by mutagenic mechanisms in the host cellular environment • De novo mutations determine the molecular spectrum of accumulated mutations during SARS-CoV-2 evolution • Molecular spectra of accumulated mutations in betacoronaviruses cluster according to the host species instead of the phylogenetic relationship • The mutations accumulated in SARS-CoV-2 prior to its transmission to humans are consistent with an evolutionary process in a bat host
    Keywords SARS-CoV-2 ; molecular spectrum ; de novo mutations ; mutational signature ; evolutionary origin ; mRNA mutation ; Science (General) ; Q1-390
    Subject code 616
    Language English
    Publishing date 2021-11-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Disome-seq reveals widespread ribosome collisions that promote cotranslational protein folding

    Taolan Zhao / Yan-Ming Chen / Yu Li / Jia Wang / Siyu Chen / Ning Gao / Wenfeng Qian

    Genome Biology, Vol 22, Iss 1, Pp 1-

    2021  Volume 35

    Abstract: Abstract Background The folding of proteins is challenging in the highly crowded and sticky environment of a cell. Regulation of translation elongation may play a crucial role in ensuring the correct folding of proteins. Much of our knowledge regarding ... ...

    Abstract Abstract Background The folding of proteins is challenging in the highly crowded and sticky environment of a cell. Regulation of translation elongation may play a crucial role in ensuring the correct folding of proteins. Much of our knowledge regarding translation elongation comes from the sequencing of mRNA fragments protected by single ribosomes by ribo-seq. However, larger protected mRNA fragments have been observed, suggesting the existence of an alternative and previously hidden layer of regulation. Results In this study, we performed disome-seq to sequence mRNA fragments protected by two stacked ribosomes, a product of translational pauses during which the 5′-elongating ribosome collides with the 3′-paused one. We detected widespread ribosome collisions that are related to slow ribosome release when stop codons are at the A-site, slow peptide bond formation from proline, glycine, asparagine, and cysteine when they are at the P-site, and slow leaving of polylysine from the exit tunnel of ribosomes. The structure of disomes obtained by cryo-electron microscopy suggests a different conformation from the substrate of the ribosome-associated protein quality control pathway. Collisions occurred more frequently in the gap regions between α-helices, where a translational pause can prevent the folding interference from the downstream peptides. Paused or collided ribosomes are associated with specific chaperones, which can aid in the cotranslational folding of the nascent peptides. Conclusions Therefore, cells use regulated ribosome collisions to ensure protein homeostasis.
    Keywords Translation elongation ; Disome-seq ; Ribosome collision ; Translational pause ; Ribosome release ; Ribosome-associated chaperones ; Biology (General) ; QH301-705.5 ; Genetics ; QH426-470
    Subject code 500
    Language English
    Publishing date 2021-01-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Reduced intrinsic DNA curvature leads to increased mutation rate

    Chaorui Duan / Qing Huan / Xiaoshu Chen / Shaohuan Wu / Lucas B. Carey / Xionglei He / Wenfeng Qian

    Genome Biology, Vol 19, Iss 1, Pp 1-

    2018  Volume 12

    Abstract: Abstract Background Mutation rates vary across the genome. Many trans factors that influence mutation rates have been identified, as have specific sequence motifs at the 1–7-bp scale, but cis elements remain poorly characterized. The lack of ... ...

    Abstract Abstract Background Mutation rates vary across the genome. Many trans factors that influence mutation rates have been identified, as have specific sequence motifs at the 1–7-bp scale, but cis elements remain poorly characterized. The lack of understanding regarding why different sequences have different mutation rates hampers our ability to identify positive selection in evolution and to identify driver mutations in tumorigenesis. Results Here, we use a combination of synthetic genes and sequences of thousands of isolated yeast colonies to show that intrinsic DNA curvature is a major cis determinant of mutation rate. Mutation rate negatively correlates with DNA curvature within genes, and a 10% decrease in curvature results in a 70% increase in mutation rate. Consistently, both yeast and humans accumulate mutations in regions with small curvature. We further show that this effect is due to differences in the intrinsic mutation rate, likely due to differences in mutagen sensitivity and not due to differences in the local activity of DNA repair. Conclusions Our study establishes a framework for understanding the cis properties of DNA sequence in modulating the local mutation rate and identifies a novel causal source of non-uniform mutation rates across the genome.
    Keywords DNA shape ; Intrinsic DNA curvature ; Mutation rate ; Mutational landscape ; Mutagen sensitivity ; Biology (General) ; QH301-705.5 ; Genetics ; QH426-470
    Subject code 612
    Language English
    Publishing date 2018-09-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Independent regulation of gene expression level and noise by histone modifications.

    Shaohuan Wu / Ke Li / Yingshu Li / Tong Zhao / Ting Li / Yu-Fei Yang / Wenfeng Qian

    PLoS Computational Biology, Vol 13, Iss 6, p e

    2017  Volume 1005585

    Abstract: The inherent stochasticity generates substantial gene expression variation among isogenic cells under identical conditions, which is frequently referred to as gene expression noise or cell-to-cell expression variability. Similar to (average) expression ... ...

    Abstract The inherent stochasticity generates substantial gene expression variation among isogenic cells under identical conditions, which is frequently referred to as gene expression noise or cell-to-cell expression variability. Similar to (average) expression level, expression noise is also subject to natural selection. Yet it has been observed that noise is negatively correlated with expression level, which manifests as a potential constraint for simultaneous optimization of both. Here, we studied expression noise in human embryonic cells with computational analysis on single-cell RNA-seq data and in yeast with flow cytometry experiments. We showed that this coupling is overcome, to a certain degree, by a histone modification strategy in multiple embryonic developmental stages in human, as well as in yeast. Importantly, this epigenetic strategy could fit into a burst-like gene expression model: promoter-localized histone modifications (such as H3K4 methylation) are associated with both burst size and burst frequency, which together influence expression level, while gene-body-localized ones (such as H3K79 methylation) are more associated with burst frequency, which influences both expression level and noise. We further knocked out the only "writer" of H3K79 methylation in yeast, and observed that expression noise is indeed increased. Consistently, dosage sensitive genes, such as genes in the Wnt signaling pathway, tend to be marked with gene-body-localized histone modifications, while stress responding genes, such as genes regulating autophagy, tend to be marked with promoter-localized ones. Our findings elucidate that the "division of labor" among histone modifications facilitates the independent regulation of expression level and noise, extend the "histone code" hypothesis to include expression noise, and shed light on the optimization of transcriptome in evolution.
    Keywords Biology (General) ; QH301-705.5
    Subject code 612 ; 570
    Language English
    Publishing date 2017-06-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Single-cell transcriptome analysis reveals widespread monoallelic gene expression in individual rice mesophyll cells

    Han, Yingying / Haopeng Yu / Wenfeng Qian / Xiao Chu / Xiu-Jie Wang / Ying-Ke Ma / Yuling Jiao

    Science China Press Science bulletin. 2017,

    2017  

    Abstract: Monoallelic gene expression refers to the phenomenon that all transcripts of a gene in a cell are expressed from only one of the two alleles in a diploid organism. Although monoallelic gene expression has been occasionally reported with bulk ... ...

    Abstract Monoallelic gene expression refers to the phenomenon that all transcripts of a gene in a cell are expressed from only one of the two alleles in a diploid organism. Although monoallelic gene expression has been occasionally reported with bulk transcriptome analysis in plants, how prevalent it is in individual plant cells remains unknown. Here, we developed a single-cell RNA-seq protocol in rice and investigated allelic expression patterns in mesophyll cells of indica (93-11) and japonica (Nipponbare) inbred lines, as well as their F1 reciprocal hybrids. We observed pervasive monoallelic gene expression in individual mesophyll cells, which could be largely explained by stochastic and independent transcription of two alleles. By contrast, two mechanisms that were proposed previously based on bulk transcriptome analyses, parent-of-origin effects and allelic repression, were not well supported by our data. Furthermore, monoallelically expressed genes exhibited a number of characteristics, such as lower expression levels, narrower H3K4me3/H3K9ac/H3K27me3 peaks, and larger expression divergences between 93-11 and Nipponbare. Taken together, the development of a single-cell RNA-seq protocol in this study offers us an excellent opportunity to investigate the origins and prevalence of monoallelic gene expression in plant cells.
    Keywords alleles ; diploidy ; gene expression ; hybrids ; inbred lines ; mesophyll ; rice ; sequence analysis ; transcription (genetics) ; transcriptomics
    Language English
    Size p. .
    Publishing place Elsevier B.V.
    Document type Article
    Note Pre-press version
    ZDB-ID 2816140-3
    ISSN 2095-9281 ; 2095-9273
    ISSN (online) 2095-9281
    ISSN 2095-9273
    DOI 10.1016/j.scib.2017.09.011
    Database NAL-Catalogue (AGRICOLA)

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  6. Article ; Online: The Genomic Landscape and Evolutionary Resolution of Antagonistic Pleiotropy in Yeast

    Wenfeng Qian / Di Ma / Che Xiao / Zhi Wang / Jianzhi Zhang

    Cell Reports, Vol 2, Iss 5, Pp 1399-

    2012  Volume 1410

    Abstract: Antagonistic pleiotropy (AP), or genetic tradeoff, is an important concept that is frequently invoked in theories of aging, cancer, genetic disease, and other common phenomena. However, the prevalence of AP, which genes are subject to AP, and to what ... ...

    Abstract Antagonistic pleiotropy (AP), or genetic tradeoff, is an important concept that is frequently invoked in theories of aging, cancer, genetic disease, and other common phenomena. However, the prevalence of AP, which genes are subject to AP, and to what extent and how AP may be resolved remain unclear. By measuring the fitness difference between the wild-type and null alleles of ∼5,000 nonessential genes in yeast, we found that in any given environment, yeast expresses hundreds of genes that harm rather than benefit the organism, demonstrating widespread AP. Nonetheless, under sufficient selection, AP is often resolvable through regulatory evolution, primarily by trans-acting changes, although in one case we also detected a cis-acting change and localized its causal mutation. However, AP is resolved more slowly in smaller populations, predicting more unresolved AP in multicellular organisms than in yeast. These findings provide an empirical foundation for AP-dependent theories and have broad biomedical and evolutionary implications.
    Keywords Biology (General) ; QH301-705.5
    Subject code 501
    Language English
    Publishing date 2012-11-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Impact of poly(A)-tail G-content on Arabidopsis PAB binding and their role in enhancing translational efficiency

    Taolan Zhao / Qing Huan / Jing Sun / Chunyan Liu / Xiuli Hou / Xiang Yu / Ian M. Silverman / Yi Zhang / Brian D. Gregory / Chun-Ming Liu / Wenfeng Qian / Xiaofeng Cao

    Genome Biology, Vol 20, Iss 1, Pp 1-

    2019  Volume 12

    Abstract: Abstract Background Polyadenylation plays a key role in producing mature mRNAs in eukaryotes. It is widely believed that the poly(A)-binding proteins (PABs) uniformly bind to poly(A)-tailed mRNAs, regulating their stability and translational efficiency. ... ...

    Abstract Abstract Background Polyadenylation plays a key role in producing mature mRNAs in eukaryotes. It is widely believed that the poly(A)-binding proteins (PABs) uniformly bind to poly(A)-tailed mRNAs, regulating their stability and translational efficiency. Results We observe that the homozygous triple mutant of broadly expressed Arabidopsis thaliana PABs, AtPAB2, AtPAB4, and AtPAB8, is embryonic lethal. To understand the molecular basis, we characterize the RNA-binding landscape of these PABs. The AtPAB-binding efficiency varies over one order of magnitude among genes. To identify the sequences accounting for the variation, we perform poly(A)-seq that directly sequences the full-length poly(A) tails. More than 10% of poly(A) tails contain at least one guanosine (G); among them, the G-content varies from 0.8 to 28%. These guanosines frequently divide poly(A) tails into interspersed A-tracts and therefore cause the variation in the AtPAB-binding efficiency among genes. Ribo-seq and genome-wide RNA stability assays show that AtPAB-binding efficiency of a gene is positively correlated with translational efficiency rather than mRNA stability. Consistently, genes with stronger AtPAB binding exhibit a greater reduction in translational efficiency when AtPAB is depleted. Conclusions Our study provides a new mechanism that translational efficiency of a gene can be regulated through the G-content-dependent PAB binding, paving the way for a better understanding of poly(A) tail-associated regulation of gene expression.
    Keywords Poly(A) tails ; Poly(A)-binding proteins ; PAB binding efficiency ; Poly(A)-tail G-content ; mRNA stability ; Translational efficiency ; Biology (General) ; QH301-705.5 ; Genetics ; QH426-470
    Subject code 500
    Language English
    Publishing date 2019-09-01T00:00:00Z
    Publisher BMC
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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