scholarly journals Eukaryotic Acquisition of a Bacterial Operon

2018 ◽  
Author(s):  
Jacek Kominek ◽  
Drew T. Doering ◽  
Dana A. Opulente ◽  
Xing-Xing Shen ◽  
Xiaofan Zhou ◽  
...  
Keyword(s):  
Messenger Rnas ◽  
Structural Rearrangements ◽  
Bacterial Genomes ◽  
Genetic Changes ◽  
Eukaryotic Genes ◽  
Eukaryotic Gene Expression ◽  
Eukaryotic Gene ◽  
Polyadenylation Sites ◽  
Insect Gut ◽  
Polycistronic Transcripts

AbstractOperons are a hallmark of bacterial genomes, where they allow concerted expression of multiple functionally related genes as single polycistronic transcripts. They are rare in eukaryotes, where each gene usually drives expression of its own independent messenger RNAs. Here we report the horizontal operon transfer of a catecholate-class siderophore biosynthesis pathway from Enterobacteriaceae into a group of closely related yeast taxa. We further show that the co-linearly arranged secondary metabolism genes are actively expressed, exhibit mainly eukaryotic transcriptional features, and enable the sequestration and uptake of iron. After transfer to the eukaryotic host, several genetic changes occurred, including the acquisition of polyadenylation sites, structural rearrangements, integration of eukaryotic genes, and secondary loss in some lineages. We conclude that the operon genes were likely captured in the shared insect gut habitat, modified for eukaryotic gene expression, and maintained by selection to adapt to the highly-competitive, iron-limited environment.

scholarly journals SPATIAL ORGANIZATION OF TRANSCRIBED EUKARYOTIC GENES

2020 ◽  
Author(s):  
Susanne Leidescher ◽  
Johannes Nübler ◽  
Yana Feodorova ◽  
Erica Hildebrand ◽  
Simon Ullrich ◽  
...  
Keyword(s):  
Gene Expression ◽  
Spatial Organization ◽  
Regulation Of Gene Expression ◽  
Spatial Arrangement ◽  
Eukaryotic Genes ◽  
Eukaryotic Gene Expression ◽  
Eukaryotic Gene ◽  
Intrinsic Stiffness ◽  
Established Role

SUMMARYDespite the well established role of nuclear organization in the regulation of gene expression, little is known about the reverse: how transcription shapes the spatial organization of the genome. In particular, given the relatively small sizes of genes and the limited resolution of light microscopy, the structure and spatial arrangement of a single transcribed gene are still poorly understood. Here, we make use of several long highly expressed mammalian genes and demonstrate that they form Transcription Loops (TLs) with polymerases moving along the loops and carrying nascent RNAs that undergo co-transcriptional splicing. TLs dynamically modify their harboring loci and extend into the nuclear interior suggesting an intrinsic stiffness. Both experimental evidence and polymer modeling support the hypothesis that TL stiffness is caused by the dense decoration of transcribed genes with multiple voluminous nascent RNPs. We propose that TL formation is a universal principle of eukaryotic gene expression.

Nucleoprotein: DNA hybridization as a preparative method to isolate specific eukaryotic genes as chromatin

1984 ◽  
Vol 42 ◽  
pp. 170-171
Author(s):  
J.L. Workman ◽  
J.P. Langmore
Keyword(s):  
Dna Sequence ◽  
Ribosomal Rna ◽  
Dna Hybridization ◽  
Protein Composition ◽  
Preparative Method ◽  
First Case ◽  
Eukaryotic Genes ◽  
Eukaryotic Gene Expression ◽  
Eukaryotic Gene ◽  
Rna Genes

Determining the structure and protein composition of chromatin in different states of genetic activity is critical for understanding eukaryotic gene expression. Very little is known about the dependence of chromatin structure upon the sequence or transcriptional activity of the DNA, except in the 2 cases in which particular genes can be isolated from the remainder of the chromatin. In the first case, active ribosomal RNA genes have been shown by EM to contain structurally altered nucleosomes. EM has also shown that SV40 minichromosomes possess a DNA sequence that is devoid of nucleosomes. Clearly, EM is capable of resolving sequence and activity specific features of chromatin, but is limited by the number of genes that have been purified.We have adapted methods of nucleic acid enzymology and hybridization in order to isolate specific genes as intact chromatin. Our methods are DNA sequence specific and thus are generally applicable to isolating a chosen gene at different points in development, differentiation and growth.

Role of small nuclear RNAs in eukaryotic gene expression

2013 ◽  
Vol 54 ◽  
pp. 79-90 ◽  
Author(s):  
Saba Valadkhan ◽  
Lalith S. Gunawardane
Keyword(s):  
Gene Expression ◽  
Protein Interactions ◽  
Rna Stability ◽  
Splice Sites ◽  
Branch Site ◽  
Small Nuclear Rnas ◽  
Eukaryotic Gene Expression ◽  
Eukaryotic Gene ◽  
Rna Biogenesis

Eukaryotic cells contain small, highly abundant, nuclear-localized non-coding RNAs [snRNAs (small nuclear RNAs)] which play important roles in splicing of introns from primary genomic transcripts. Through a combination of RNA–RNA and RNA–protein interactions, two of the snRNPs, U1 and U2, recognize the splice sites and the branch site of introns. A complex remodelling of RNA–RNA and protein-based interactions follows, resulting in the assembly of catalytically competent spliceosomes, in which the snRNAs and their bound proteins play central roles. This process involves formation of extensive base-pairing interactions between U2 and U6, U6 and the 5′ splice site, and U5 and the exonic sequences immediately adjacent to the 5′ and 3′ splice sites. Thus RNA–RNA interactions involving U2, U5 and U6 help position the reacting groups of the first and second steps of splicing. In addition, U6 is also thought to participate in formation of the spliceosomal active site. Furthermore, emerging evidence suggests additional roles for snRNAs in regulation of various aspects of RNA biogenesis, from transcription to polyadenylation and RNA stability. These snRNP-mediated regulatory roles probably serve to ensure the co-ordination of the different processes involved in biogenesis of RNAs and point to the central importance of snRNAs in eukaryotic gene expression.

scholarly journals Nascent RNA sequencing identifies a widespread sigma70-dependent pausing regulated by Gre factors in bacteria

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhe Sun ◽  
Alexander V. Yakhnin ◽  
Peter C. FitzGerald ◽  
Carl E. Mclntosh ◽  
Mikhail Kashlev
Keyword(s):  
Environmental Cues ◽  
Start Site ◽  
Transcription Start ◽  
Genome Wide Analysis ◽  
Genome Wide ◽  
Eukaryotic Gene Expression ◽  
Eukaryotic Gene ◽  
Vitro Analysis ◽  
In Vitro Analysis

AbstractPromoter-proximal pausing regulates eukaryotic gene expression and serves as checkpoints to assemble elongation/splicing machinery. Little is known how broadly this type of pausing regulates transcription in bacteria. We apply nascent elongating transcript sequencing combined with RNase I footprinting for genome-wide analysis of σ70-dependent transcription pauses in Escherichia coli. Retention of σ70 induces strong backtracked pauses at a 10−20-bp distance from many promoters. The pauses in the 10−15-bp register of the promoter are dictated by the canonical −10 element, 6−7 nt spacer and “YR+1Y” motif centered at the transcription start site. The promoters for the pauses in the 16−20-bp register contain an additional −10-like sequence recognized by σ70. Our in vitro analysis reveals that DNA scrunching is involved in these pauses relieved by Gre cleavage factors. The genes coding for transcription factors are enriched in these pauses, suggesting that σ70 and Gre proteins regulate transcription in response to changing environmental cues.

scholarly journals An antisense noncoding RNA enhances translation via localised structural rearrangements of its cognate mRNA

2021 ◽  
Author(s):  
Rodrigo S Reis ◽  
Jules Deforges ◽  
Romy R Schmidt ◽  
Jos H M Schippers ◽  
Yves Poirier
Keyword(s):  
Antisense Rna ◽  
Noncoding Rna ◽  
Regulatory Region ◽  
Structural Rearrangement ◽  
Start Codon ◽  
Structural Rearrangements ◽  
Eukaryotic Genes ◽  
Inhibitory Region ◽  
Rna Interaction

Abstract A large portion of eukaryotic genes are associated with noncoding, natural antisense transcripts (NATs). Despite sharing extensive sequence complementarity with their sense mRNAs, mRNA-NAT pairs elusively often evade dsRNA-cleavage and siRNA-triggered silencing. More surprisingly, some NATs enhance translation of their sense mRNAs by yet unknown mechanism(s). Here we show that translation enhancement of the rice (Oryza sativa) PHOSPHATE1.2 (PHO1.2) mRNA is enabled by specific structural rearrangements guided by its noncoding antisense RNA (cis-NATpho1.2). Their interaction in vitro revealed no evidence of widespread intermolecular dsRNA formation, but rather specific local changes in nucleotide base-pairing, leading to higher flexibility of PHO1.2 mRNA at a key high GC regulatory region inhibiting translation, approximately 350 nucleotides downstream of the start codon. Sense-antisense RNA interaction increased formation of the 80S complex in PHO1.2, possibly by inducing structural rearrangement within this inhibitory region, thus making this mRNA more accessible to 60S. This work presents a framework for nucleotide-resolution studies of functional mRNA-antisense pairs. One-sentence summary: Interaction between PHO1.2 mRNA and its cis-natural antisense transcript enhances translation via a mechanism involving a local conformational shift and disruption of a key inhibitory region.

Implications of DNA replication for eukaryotic gene expression

1991 ◽  
Vol 99 (2) ◽  
pp. 201-206 ◽  
Author(s):  
A.P. Wolffe
Keyword(s):  
Gene Expression ◽  
Dna Replication ◽  
Replication Fork ◽  
Recent Progress ◽  
Gene Activity ◽  
Nucleosome Assembly ◽  
Developmental Processes ◽  
Eukaryotic Gene Expression ◽  
Eukaryotic Gene

DNA replication has a key role in many developmental processes. Recent progress in understanding events at the replication fork suggests mechanisms for both establishing and maintaining programs of eukaryotic gene activity. In this review, I discuss the consequences of replication fork passage for preexisting chromatin structures and describe how the mechanism of nucleosome assembly at the replication fork may facilitate the formation of either transcriptionally active or repressed chromatin.

Reduction in gene expression noise by targeted increase in accessibility at gene loci

2021 ◽  
Vol 118 (42) ◽  
pp. e2018640118
Author(s):  
LaTasha C. R. Fraser ◽  
Ryan J. Dikdan ◽  
Supravat Dey ◽  
Abhyudai Singh ◽  
Sanjay Tyagi
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Single Molecule ◽  
Single Cells ◽  
Global Changes ◽  
Messenger Rnas ◽  
Histone Acetyl Transferase ◽  
Gene Expression Noise ◽  
Expression Noise ◽  
Eukaryotic Genes

Many eukaryotic genes are expressed in randomly initiated bursts that are punctuated by periods of quiescence. Here, we show that the intermittent access of the promoters to transcription factors through relatively impervious chromatin contributes to this “noisy” transcription. We tethered a nuclease-deficient Cas9 fused to a histone acetyl transferase at the promoters of two endogenous genes in HeLa cells. An assay for transposase-accessible chromatin using sequencing showed that the activity of the histone acetyl transferase altered the chromatin architecture locally without introducing global changes in the nucleus and rendered the targeted promoters constitutively accessible. We measured the gene expression variability from the gene loci by performing single-molecule fluorescence in situ hybridization against mature messenger RNAs (mRNAs) and by imaging nascent mRNA molecules present at active gene loci in single cells. Because of the increased accessibility of the promoter to transcription factors, the transcription from two genes became less noisy, even when the average levels of expression did not change. In addition to providing evidence for chromatin accessibility as a determinant of the noise in gene expression, our study offers a mechanism for controlling gene expression noise which is otherwise unavoidable.

Integrated databases and computer systems for studying eukaryotic gene expression

1999 ◽  
Vol 15 (7) ◽  
pp. 669-686 ◽  
Author(s):  
N. A. Kolchanov ◽  
M. P. Ponomarenko ◽  
A. S. Frolov ◽  
E. A. Ananko ◽  
F. A. Kolpakov ◽  
...  
Keyword(s):  
Gene Expression ◽  
Computer Systems ◽  
Eukaryotic Gene Expression ◽  
Eukaryotic Gene
Sign in / Sign up

Export Citation Format

Share Document