scholarly journals Extensive splicing across the Saccharomyces cerevisiae genome

2019 ◽  
Author(s):  
Stephen M. Douglass ◽  
Calvin S. Leung ◽  
Tracy L. Johnson

AbstractPre-mRNA splicing is vital for the proper function and regulation of eukaryotic gene expression. Saccharomyces cerevisiae has been used as a model organism for studies of RNA splicing because of the striking conservation of the spliceosome components and its catalytic activity. Nonetheless, there are relatively few annotated alternative splice forms, particularly when compared to higher eukaryotes. Here, we describe a method to combine large scale RNA sequencing data to accurately discover novel splice isoforms in Saccharomyces cerevisiae. Using our method, we find extensive evidence for novel splicing of annotated intron-containing genes as well as genes without previously annotated introns and splicing of transcripts that are antisense to annotated genes. By incorporating several mutant strains at varied temperatures, we find conditions which lead to differences in alternative splice form usage. Despite this, every class and category of alternative splicing we find in our datasets is found, often at lower frequency, in wildtype cells under normal growth conditions. Together, these findings show that there is widespread splicing in Saccharomyces cerevisiae, thus expanding our view of the regulatory potential of RNA splicing in yeast.Author SummaryPre-mRNA splicing is a fundamental step in eukaryotic gene expression. Saccharomyces cerevisiae, also known as brewer’s yeast, is a model organism for the study of pre-mRNA splicing in eukaryotes. Through the process of pre-mRNA splicing, a single gene is capable of encoding multiple mature mRNA products, but it is often difficult to identify the splice events that lead to these mRNA products. Here, we describe a method to accurately discover novel splice events in Saccharomyces cerevisiae and find evidence for extensive splicing in Saccharomyces. By utilizing a variety of strains and growth conditions, we are able to characterize many splice forms and correlate cellular conditions with prevalence of novel splice events.

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Martin Převorovský ◽  
Martina Hálová ◽  
Kateřina Abrhámová ◽  
Jiří Libus ◽  
Petr Folk

Pre-mRNA splicing represents an important regulatory layer of eukaryotic gene expression. In the simple budding yeast Saccharomyces cerevisiae, about one-third of all mRNA molecules undergo splicing, and splicing efficiency is tightly regulated, for example, during meiotic differentiation. S. cerevisiae features a streamlined, evolutionarily highly conserved splicing machinery and serves as a favourite model for studies of various aspects of splicing. RNA-seq represents a robust, versatile, and affordable technique for transcriptome interrogation, which can also be used to study splicing efficiency. However, convenient bioinformatics tools for the analysis of splicing efficiency from yeast RNA-seq data are lacking. We present a complete workflow for the calculation of genome-wide splicing efficiency in S. cerevisiae using strand-specific RNA-seq data. Our pipeline takes sequencing reads in the FASTQ format and provides splicing efficiency values for the 5′ and 3′ splice junctions of each intron. The pipeline is based on up-to-date open-source software tools and requires very limited input from the user. We provide all relevant scripts in a ready-to-use form. We demonstrate the functionality of the workflow using RNA-seq datasets from three spliceosome mutants. The workflow should prove useful for studies of yeast splicing mutants or of regulated splicing, for example, under specific growth conditions.


2019 ◽  
Vol 20 (13) ◽  
pp. 3278 ◽  
Author(s):  
Koh Nakayama ◽  
Naoyuki Kataoka

Eukaryotes are often subjected to different kinds of stress. In order to adjust to such circumstances, eukaryotes activate stress–response pathways and regulate gene expression. Eukaryotic gene expression consists of many different steps, including transcription, RNA processing, RNA transport, and translation. In this review article, we focus on both transcriptional and post-transcriptional regulations of gene expression under hypoxic conditions. In the first part of the review, transcriptional regulations mediated by various transcription factors including Hypoxia-Inducible Factors (HIFs) are described. In the second part, we present RNA splicing regulations under hypoxic conditions, which are mediated by splicing factors and their kinases. This work summarizes and discusses the emerging studies of those two gene expression machineries under hypoxic conditions.


2013 ◽  
Vol 54 ◽  
pp. 79-90 ◽  
Author(s):  
Saba Valadkhan ◽  
Lalith S. Gunawardane

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.


1991 ◽  
Vol 99 (2) ◽  
pp. 201-206 ◽  
Author(s):  
A.P. Wolffe

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.


1999 ◽  
Vol 15 (7) ◽  
pp. 669-686 ◽  
Author(s):  
N. A. Kolchanov ◽  
M. P. Ponomarenko ◽  
A. S. Frolov ◽  
E. A. Ananko ◽  
F. A. Kolpakov ◽  
...  

2006 ◽  
Vol 26 (8) ◽  
pp. 3149-3163 ◽  
Author(s):  
Christophe Leroy ◽  
Laëtitia Cormier ◽  
Laurent Kuras

ABSTRACT Mediator is a key RNA polymerase II (Pol II) cofactor in the regulation of eukaryotic gene expression. It is believed to function as a coactivator linking gene-specific activators to the basal Pol II initiation machinery. In support of this model, we provide evidence that Mediator serves in vivo as a coactivator for the yeast activator Met4, which controls the gene network responsible for the biosynthesis of sulfur-containing amino acids and S-adenosylmethionine. In addition, we show that SAGA (Spt-Ada-Gcn5-acetyltransferase) is also recruited to Met4 target promoters, where it participates in the recruitment of Pol II by a mechanism involving histone acetylation. Interestingly, we find that SAGA is not required for Mediator recruitment by Met4 and vice versa. Our results provide a novel example of functional interplay between Mediator and coactivators involved in histone modification.


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