1
|
Reingewertz TH, Ben-Maimon M, Zafrir Z, Tuller T, Horovitz A. Synonymous and non-synonymous codon substitutions can alleviate dependence on GroEL for folding. Protein Sci 2024; 33:e5087. [PMID: 39074255 DOI: 10.1002/pro.5087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 06/03/2024] [Accepted: 06/05/2024] [Indexed: 07/31/2024]
Abstract
The Escherichia coli GroEL/ES chaperonin system facilitates protein folding in an ATP-driven manner. There are <100 obligate clients of this system in E. coli although GroEL can interact and assist the folding of a multitude of proteins in vitro. It has remained unclear, however, which features distinguish obligate clients from all the other proteins in an E. coli cell. To address this question, we established a system for selecting mutations in mouse dihydrofolate reductase (mDHFR), a GroEL interactor, that diminish its dependence on GroEL for folding. Strikingly, both synonymous and non-synonymous codon substitutions were found to reduce mDHFR's dependence on GroEL. The non-synonymous substitutions increase the rate of spontaneous folding whereas computational analysis indicates that the synonymous substitutions appear to affect translation rates at specific sites.
Collapse
Affiliation(s)
- Tali Haviv Reingewertz
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Miki Ben-Maimon
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Zohar Zafrir
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, Tel Aviv University, Tel Aviv, Israel
- The Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel
| | - Amnon Horovitz
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| |
Collapse
|
2
|
Smith CB, Gao A, Bravo P, Alam A. Microbial Metabolite Trimethylamine N-Oxide Promotes Campylobacter jejuni Infection by Escalating Intestinal Inflammation, Epithelial Damage, and Barrier Disruption. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.10.588895. [PMID: 38645062 PMCID: PMC11030326 DOI: 10.1101/2024.04.10.588895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
The interactions between Campylobacter jejuni , a critical foodborne cause of gastroenteritis, and the intestinal microbiota during infection are not completely understood. The crosstalk between C. jejuni and its host is impacted by the gut microbiota through mechanisms of competitive exclusion, microbial metabolites, or immune response. To investigate the role of gut microbiota on C. jejuni pathogenesis, we examined campylobacteriosis in the IL10KO mouse model, which was characterized by an increase in the relative abundance of intestinal proteobacteria, E. coli , and inflammatory cytokines during C. jejuni infection. We also found a significantly increased abundance of microbial metabolite Trimethylamine N-Oxide (TMAO) in the colonic lumens of IL10KO mice. We further investigated the effects of TMAO on C. jejuni pathogenesis. We determined that C. jejuni senses TMAO as a chemoattractant and the administration of TMAO promotes C. jejuni invasion into Caco-2 monolayers. TMAO also increased the transmigration of C. jejuni across polarized monolayers of Caco-2 cells, decreased TEER, and increased C. jejuni -mediated intestinal barrier damage. Interestingly, TMAO treatment and presence during C. jejuni infection of Caco-2 cells synergistically caused an increased inflammatory cytokine expression, specifically IL-1β and IL-8. These results establish that C. jejuni utilizes microbial metabolite TMAO for increased virulence during infection.
Collapse
|
3
|
Granillo-Luna ON, Hernandez-Aguirre LE, Peregrino-Uriarte AB, Duarte-Gutierrez J, Contreras-Vergara CA, Gollas-Galvan T, Yepiz-Plascencia G. The anaplerotic pyruvate carboxylase from white shrimp Litopenaeus vannamei: Gene structure, molecular characterization, protein modelling and expression during hypoxia. Comp Biochem Physiol A Mol Integr Physiol 2022; 269:111212. [PMID: 35417748 DOI: 10.1016/j.cbpa.2022.111212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 10/18/2022]
Abstract
Hypoxic zones are spreading worldwide in marine environments affecting many organisms. Shrimp and other marine crustaceans can withstand environmental hypoxia using several strategies, including the regulation of energy producing metabolic pathways. Pyruvate carboxylase (PC) catalyzes the first reaction of gluconeogenesis to produce oxaloacetate from pyruvate. In mammals, PC also participates in lipogenesis, insulin secretion and other processes, but this enzyme has been scarcely studied in marine invertebrates. In this work, we characterized the gene encoding PC in the white shrimp Litopenaeus vannamei, modelled the protein structure and evaluated its gene expression in hepatopancreas during hypoxia, as well as glucose and lactate concentrations. The PC gene codes for a mitochondrial protein and has 21 coding exons and 4 non-coding exons that generate three transcript variants with differences only in the 5'-UTR. Total PC expression is more abundant in hepatopancreas compared to gills or muscle, indicating tissue-specific expression. Under hypoxic conditions of 1.53 mg/L dissolved oxygen, PC expression is maintained in hepatopancreas, indicating its key role even in energy-limited conditions. Finally, both glucose and lactate concentrations were maintained under hypoxia for 24-48 h in hepatopancreas.
Collapse
Affiliation(s)
- Omar N Granillo-Luna
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A. C., Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col. La Victoria, Hermosillo, Sonora, C. P. 83304, Mexico
| | - Laura E Hernandez-Aguirre
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A. C., Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col. La Victoria, Hermosillo, Sonora, C. P. 83304, Mexico
| | - Alma B Peregrino-Uriarte
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A. C., Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col. La Victoria, Hermosillo, Sonora, C. P. 83304, Mexico
| | - Jorge Duarte-Gutierrez
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A. C., Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col. La Victoria, Hermosillo, Sonora, C. P. 83304, Mexico
| | - Carmen A Contreras-Vergara
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A. C., Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col. La Victoria, Hermosillo, Sonora, C. P. 83304, Mexico
| | - Teresa Gollas-Galvan
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A. C., Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col. La Victoria, Hermosillo, Sonora, C. P. 83304, Mexico
| | - Gloria Yepiz-Plascencia
- Centro de Investigación en Alimentación y Desarrollo (CIAD), A. C., Carretera Gustavo Enrique Astiazarán Rosas, no. 46, Col. La Victoria, Hermosillo, Sonora, C. P. 83304, Mexico.
| |
Collapse
|
4
|
Abstract
The development of safe and effective vaccines against viruses is central to disease control. With advancements in DNA synthesis technology, the production of synthetic viral genomes has fueled many research efforts that aim to generate attenuated viruses by introducing synonymous mutations. Elucidation of the mechanisms underlying virus attenuation through synonymous mutagenesis is revealing interesting new biology that can be exploited for vaccine development. Here, we review recent advancements in this field of synthetic virology and focus on the molecular mechanisms of attenuation by genetic recoding of viruses. We highlight the action of the zinc finger antiviral protein (ZAP) and RNase L, two proteins involved in the inhibition of viruses enriched for CpG and UpA dinucleotides, that are often the products of virus recoding algorithms. Additionally, we discuss current challenges in the field as well as studies that may illuminate how other host functions, such as translation, are potentially involved in the attenuation of recoded viruses.
Collapse
|
5
|
Exploring Potential Signals of Selection for Disordered Residues in Prokaryotic and Eukaryotic Proteins. GENOMICS PROTEOMICS & BIOINFORMATICS 2020; 18:549-564. [PMID: 33346088 PMCID: PMC8377245 DOI: 10.1016/j.gpb.2020.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 03/29/2020] [Accepted: 06/10/2020] [Indexed: 11/22/2022]
Abstract
Intrinsically disordered proteins (IDPs) are an important class of proteins in all domains of life for their functional importance. However, how nature has shaped the disorder potential of prokaryotic and eukaryotic proteins is still not clearly known. Randomly generated sequences are free of any selective constraints, thus these sequences are commonly used as null models. Considering different types of random protein models, here we seek to understand how the disorder potential of natural eukaryotic and prokaryotic proteins differs from random sequences. Comparing proteome-wide disorder content between real and random sequences of 12 model organisms, we noticed that eukaryotic proteins are enriched in disordered regions compared to random sequences, but in prokaryotes such regions are depleted. By analyzing the position-wise disorder profile, we show that there is a generally higher disorder near the N- and C-terminal regions of eukaryotic proteins as compared to the random models; however, either no or a weak such trend was found in prokaryotic proteins. Moreover, here we show that this preference is not caused by the amino acid or nucleotide composition at the respective sites. Instead, these regions were found to be endowed with a higher fraction of protein–protein binding sites, suggesting their functional importance. We discuss several possible explanations for this pattern, such as improving the efficiency of protein–protein interaction, ribosome movement during translation, and post-translational modification. However, further studies are needed to clearly understand the biophysical mechanisms causing the trend.
Collapse
|
6
|
Weiner I, Feldman Y, Shahar N, Yacoby I, Tuller T. CSO – A sequence optimization software for engineering chloroplast expression in Chlamydomonas reinhardtii. ALGAL RES 2020. [DOI: 10.1016/j.algal.2019.101788] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
7
|
Kiening M, Ochsenreiter R, Hellinger HJ, Rattei T, Hofacker I, Frishman D. Conserved Secondary Structures in Viral mRNAs. Viruses 2019; 11:E401. [PMID: 31035717 PMCID: PMC6563262 DOI: 10.3390/v11050401] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 04/23/2019] [Accepted: 04/26/2019] [Indexed: 12/29/2022] Open
Abstract
RNA secondary structure in untranslated and protein coding regions has been shown to play an important role in regulatory processes and the viral replication cycle. While structures in non-coding regions have been investigated extensively, a thorough overview of the structural repertoire of protein coding mRNAs, especially for viruses, is lacking. Secondary structure prediction of large molecules, such as long mRNAs remains a challenging task, as the contingent of structures a sequence can theoretically fold into grows exponentially with sequence length. We applied a structure prediction pipeline to Viral Orthologous Groups that first identifies the local boundaries of potentially structured regions and subsequently predicts their functional importance. Using this procedure, the orthologous groups were split into structurally homogenous subgroups, which we call subVOGs. This is the first compilation of potentially functional conserved RNA structures in viral coding regions, covering the complete RefSeq viral database. We were able to recover structural elements from previous studies and discovered a variety of novel structured regions. The subVOGs are available through our web resource RNASIV (RNA structure in viruses; http://rnasiv.bio.wzw.tum.de).
Collapse
Affiliation(s)
- Michael Kiening
- Department of Bioinformatics, Wissenschaftszentrum Weihenstephan, Technische Universität München, Maximus-von-Imhof-Forum 3, D-85354 Freising, Germany.
| | - Roman Ochsenreiter
- University of Vienna, Faculty of Computer Science, Research Group Bioinformatics and Computational Biology, Währingerstr. 29, 1090 Vienna, Austria.
| | - Hans-Jörg Hellinger
- Division of Computational Systems Biology, Department of Microbiology and Ecosystem Science, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
| | - Thomas Rattei
- Division of Computational Systems Biology, Department of Microbiology and Ecosystem Science, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
| | - Ivo Hofacker
- University of Vienna, Faculty of Computer Science, Research Group Bioinformatics and Computational Biology, Währingerstr. 29, 1090 Vienna, Austria.
- University of Vienna, Faculty of Chemistry, Department of Theoretical Chemistry, Währingerstrasse 17, 1090 Vienna, Austria.
| | - Dmitrij Frishman
- Department of Bioinformatics, Wissenschaftszentrum Weihenstephan, Technische Universität München, Maximus-von-Imhof-Forum 3, D-85354 Freising, Germany.
- St Petersburg State Polytechnic University, St Petersburg 195251, Russia.
| |
Collapse
|
8
|
Phylogenomic analysis unravels evolution of yellow fever virus within hosts. PLoS Negl Trop Dis 2018; 12:e0006738. [PMID: 30188905 PMCID: PMC6143276 DOI: 10.1371/journal.pntd.0006738] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 09/18/2018] [Accepted: 08/07/2018] [Indexed: 11/30/2022] Open
Abstract
The yellow fever virus (YFV) recently reemerged in the large outbreaks in Africa and Brazil, and the first imported patients into Asia have recalled the concerns of YFV evolution. Here we show phylogenomics of YFV with serial clinical samples of the 2016 YFV infections. Phylogenetics exhibited that the 2016 strains were close to Angola 1971 strains and only three amino acid changes presented new to other lineages. Deep sequencing of viral genomes discovered 101 intrahost single nucleotide variations (iSNVs) and 234 single nucleotide polymorphisms (SNPs). Analysis of iSNV distribution and mutated allele frequency revealed that the coding regions were under purifying selection. Comparison of the evolutionary rates estimated by iSNV and SNP showed that the intrahost rate was ~2.25 times higher than the epidemic rate, and both rates were higher than the long-term YFV substitution rate, as expected. In addition, the result also hinted that short viremia duration of YFV might further hinder the evolution of YFV. The first importation of infections into China in 2016 and the following outbreaks in Africa and Brazil of yellow fever virus (YFV) have raised again the concerns of the potential viral spread into new territories. In this study, we aimed to know the evolution dynamics of YFV by using intrahost phylogenomics and to assess the risk of virus epidemics. Through deep sequencing of consecutive samples from 12 patients, we identified hundreds of genomic variations (iSNVs and SNPs), and noticed the nearly linear accumulation of variations within individuals. The estimated evolutionary rate within host is much higher than the epidemic evolutionary rate. In comparison with Dengue virus (DENV) and Zika virus (ZIKV), which share similar host vectors (Aedes spp.), life cycles, mutation rates and replication strategies to YFV, the lower epidemic evolutionary rate of YFV might have been hindered by the shorter viremia duration, which decreased the accumulated variations to get into the transmission cycle.
Collapse
|
9
|
Abstract
Live viral vaccines rely on attenuated viruses that can successfully infect their host but have reduced fitness or virulence. Such attenuated viruses were originally developed through trial and error, typically by adaptation of the wild-type virus to novel conditions. That method was haphazard, with no way of controlling the degree of attenuation or the number of attenuating mutations or preventing evolutionary reversion. Synthetic biology now enables rational design and engineering of viral attenuation, but rational design must be informed by biological principles to achieve stable, quantitative attenuation. This work shows that in a model system for viral attenuation, bacteriophage T7, attenuation can be obtained from rational design principles, and multiple different attenuation approaches can be combined for enhanced overall effect. Attenuated viruses have numerous applications, in particular in the context of live viral vaccines. However, purposefully designing attenuated viruses remains challenging, in particular if the attenuation is meant to be resistant to rapid evolutionary recovery. Here we develop and analyze a new attenuation method, promoter ablation, using an established viral model, bacteriophage T7. Ablation of promoters of the two most highly expressed T7 proteins (scaffold and capsid) led to major reductions in transcript abundance of the affected genes, with the effect of the double knockout approximately additive of the effects of single knockouts. Fitness reduction was moderate and also approximately additive; fitness recovery on extended adaptation was partial and did not restore the promoters. The fitness effect of promoter knockouts combined with a previously tested codon deoptimization of the capsid gene was less than additive, as anticipated from their competing mechanisms of action. In one design, the engineering created an unintended consequence that led to further attenuation, the effect of which was studied and understood in hindsight. Overall, the mechanisms and effects of genome engineering on attenuation behaved in a predictable manner. Therefore, this work suggests that the rational design of viral attenuation methods is becoming feasible. IMPORTANCE Live viral vaccines rely on attenuated viruses that can successfully infect their host but have reduced fitness or virulence. Such attenuated viruses were originally developed through trial and error, typically by adaptation of the wild-type virus to novel conditions. That method was haphazard, with no way of controlling the degree of attenuation or the number of attenuating mutations or preventing evolutionary reversion. Synthetic biology now enables rational design and engineering of viral attenuation, but rational design must be informed by biological principles to achieve stable, quantitative attenuation. This work shows that in a model system for viral attenuation, bacteriophage T7, attenuation can be obtained from rational design principles, and multiple different attenuation approaches can be combined for enhanced overall effect.
Collapse
|
10
|
Abstract
Background Synthetic virology is an important multidisciplinary scientific field, with emerging applications in biotechnology and medicine, aiming at developing methods to generate and engineer synthetic viruses. In particular, many of the RNA viruses, including among others the Dengue and Zika, are widespread pathogens of significant importance to human health. The ability to design and synthesize such viruses may contribute to exploring novel approaches for developing vaccines and virus based therapies. Results Here we develop a full multidisciplinary pipeline for generation and analysis of synthetic RNA viruses and specifically apply it to Dengue virus serotype 2 (DENV-2). The major steps of the pipeline include comparative genomics of endogenous and synthetic viral strains. Specifically, we show that although the synthetic DENV-2 viruses were found to have lower nucleotide variability, their phenotype, as reflected in the study of the AG129 mouse model morbidity, RNA levels, and neutralization antibodies, is similar or even more pathogenic in comparison to the wildtype master strain. Additionally, the highly variable positions, identified in the analyzed DENV-2 population, were found to overlap with less conserved homologous positions in Zika virus and other Dengue serotypes. These results may suggest that synthetic DENV-2 could enhance virulence if the correct sequence is selected. Conclusions The approach reported in this study can be used to generate and analyze synthetic RNA viruses both on genotypic and on phenotypic level. It could be applied for understanding the functionality and the fitness effects of any set of mutations in viral RNA and for editing RNA viruses for various target applications. Electronic supplementary material The online version of this article (10.1186/s12859-018-2132-3) contains supplementary material, which is available to authorized users.
Collapse
|
11
|
Abstract
The two major steps of gene expression are transcription and translation. While hundreds of studies regarding the effect of sequence features on the translation elongation process have been published, very few connect sequence features to the transcription elongation rate. We suggest, for the first time, that short transcript sub-sequences have a typical effect on RNA polymerase (RNAP) speed: we show that nucleotide 5-mers tend to have typical RNAP speed (or transcription rate), which is consistent along different parts of genes and among different groups of genes with high correlation. We also demonstrate that relative RNAP speed correlates with mRNA levels of endogenous and heterologous genes. Furthermore, we show that the estimated transcription and translation elongation rates correlate in endogenous genes. Finally, we demonstrate that our results are consistent for different high resolution experimental measurements of RNAP densities. These results suggest for the first time that transcription elongation is partly encoded in the transcript, affected by the codon-usage, and optimized by evolution with a significant effect on gene expression and organismal fitness.
Collapse
Affiliation(s)
- Eyal Cohen
- a Balavatnick School of Computer Science , Tel Aviv University , Tel Aviv , Israel
| | - Zohar Zafrir
- b Department of Biomedical Engineering , Tel Aviv University , Tel Aviv , Israel
| | - Tamir Tuller
- b Department of Biomedical Engineering , Tel Aviv University , Tel Aviv , Israel.,c Sagol School of Neuroscience , Tel Aviv University , Tel Aviv , Israel
| |
Collapse
|
12
|
Goz E, Mioduser O, Diament A, Tuller T. Evidence of translation efficiency adaptation of the coding regions of the bacteriophage lambda. DNA Res 2017; 24:333-342. [PMID: 28338832 PMCID: PMC5737525 DOI: 10.1093/dnares/dsx005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 02/01/2017] [Indexed: 11/15/2022] Open
Abstract
Deciphering the way gene expression regulatory aspects are encoded in viral genomes is a challenging mission with ramifications related to all biomedical disciplines. Here, we aimed to understand how the evolution shapes the bacteriophage lambda genes by performing a high resolution analysis of ribosomal profiling data and gene expression related synonymous/silent information encoded in bacteriophage coding regions. We demonstrated evidence of selection for distinct compositions of synonymous codons in early and late viral genes related to the adaptation of translation efficiency to different bacteriophage developmental stages. Specifically, we showed that evolution of viral coding regions is driven, among others, by selection for codons with higher decoding rates; during the initial/progressive stages of infection the decoding rates in early/late genes were found to be superior to those in late/early genes, respectively. Moreover, we argued that selection for translation efficiency could be partially explained by adaptation to Escherichia coli tRNA pool and the fact that it can change during the bacteriophage life cycle. An analysis of additional aspects related to the expression of viral genes, such as mRNA folding and more complex/longer regulatory signals in the coding regions, is also reported. The reported conclusions are likely to be relevant also to additional viruses.
Collapse
Affiliation(s)
- Eli Goz
- Department of Biomedical Engineering, Tel-Aviv University, Ramat Aviv 69978, Israel.,SynVaccine Ltd Ramat Hachayal, Tel Aviv 6971039, Israel
| | - Oriah Mioduser
- Department of Biomedical Engineering, Tel-Aviv University, Ramat Aviv 69978, Israel
| | - Alon Diament
- Department of Biomedical Engineering, Tel-Aviv University, Ramat Aviv 69978, Israel
| | - Tamir Tuller
- Department of Biomedical Engineering, Tel-Aviv University, Ramat Aviv 69978, Israel.,SynVaccine Ltd Ramat Hachayal, Tel Aviv 6971039, Israel.,Sagol School of Neuroscience, Tel-Aviv University, Ramat Aviv 69978, Israel
| |
Collapse
|
13
|
Qi F, Frishman D. Melting temperature highlights functionally important RNA structure and sequence elements in yeast mRNA coding regions. Nucleic Acids Res 2017; 45:6109-6118. [PMID: 28335026 PMCID: PMC5449622 DOI: 10.1093/nar/gkx161] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 02/24/2017] [Indexed: 11/13/2022] Open
Abstract
Secondary structure elements in the coding regions of mRNAs play an important role in gene expression and regulation, but distinguishing functional from non-functional structures remains challenging. Here we investigate the dependence of sequence–structure relationships in the coding regions on temperature based on the recent PARTE data by Wan et al. Our main finding is that the regions with high and low thermostability (high Tm and low Tm regions) are under evolutionary pressure to preserve RNA secondary structure and primary sequence, respectively. Sequences of low Tm regions display a higher degree of evolutionary conservation compared to high Tm regions. Low Tm regions are under strong synonymous constraint, while high Tm regions are not. These findings imply that high Tm regions contain thermo-stable functionally important RNA structures, which impose relaxed evolutionary constraint on sequence as long as the base-pairing patterns remain intact. By contrast, low thermostability regions contain single-stranded functionally important conserved RNA sequence elements accessible for binding by other molecules. We also find that theoretically predicted structures of paralogous mRNA pairs become more similar with growing temperature, while experimentally measured structures tend to diverge, which implies that the melting pathways of RNA structures cannot be fully captured by current computational approaches.
Collapse
Affiliation(s)
- Fei Qi
- Department of Bioinformatics, Technische Universität München, Wissenschaftzentrum Weihenstephan, Maximus-von-Imhof-Forum 3, D-85354 Freising, Germany
| | - Dmitrij Frishman
- Department of Bioinformatics, Technische Universität München, Wissenschaftzentrum Weihenstephan, Maximus-von-Imhof-Forum 3, D-85354 Freising, Germany.,St Petersburg State Polytechnic University, St Petersburg 195251, Russia
| |
Collapse
|
14
|
Abstract
This paper reports on the various nuances of the origins of life on Earth and highlights the latest findings in that arena as reported at the Network of Researchers on Horizontal Gene Transfer and the Last Universal Common Ancestor (NoR HGT and LUCA) which was held from the 3–4th November 2016 at the Open University, UK. Although the answers to the question of the origin of life on Earth will not be fathomable anytime soon, a wide variety of subject matter was able to be covered, ranging from examining what constitutes a LUCA, looking at viral connections and “from RNA to DNA”, i.e., could DNA have been formed simultaneously with RNA, rather than RNA first and then describing the emergence of DNA from RNA. Also discussed are proteins and the origins of genomes as well as various ideas that purport to explain the origin of life here on Earth and potentially further afield elsewhere on other planets.
Collapse
Affiliation(s)
- Sohan Jheeta
- Network of Researchers on Horizontal Gene Transfer and the Last Universal Common Ancestor (NoR HGT & LUCA), Leeds LS7 3RB, UK.
| |
Collapse
|
15
|
Zarai Y, Margaliot M, Tuller T. Optimal Down Regulation of mRNA Translation. Sci Rep 2017; 7:41243. [PMID: 28120903 PMCID: PMC5264618 DOI: 10.1038/srep41243] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 12/19/2016] [Indexed: 01/02/2023] Open
Abstract
Down regulation of mRNA translation is an important problem in various bio-medical domains ranging from developing effective medicines for tumors and for viral diseases to developing attenuated virus strains that can be used for vaccination. Here, we study the problem of down regulation of mRNA translation using a mathematical model called the ribosome flow model (RFM). In the RFM, the mRNA molecule is modeled as a chain of n sites. The flow of ribosomes between consecutive sites is regulated by n + 1 transition rates. Given a set of feasible transition rates, that models the outcome of all possible mutations, we consider the problem of maximally down regulating protein production by altering the rates within this set of feasible rates. Under certain conditions on the feasible set, we show that an optimal solution can be determined efficiently. We also rigorously analyze two special cases of the down regulation optimization problem. Our results suggest that one must focus on the position along the mRNA molecule where the transition rate has the strongest effect on the protein production rate. However, this rate is not necessarily the slowest transition rate along the mRNA molecule. We discuss some of the biological implications of these results.
Collapse
Affiliation(s)
- Yoram Zarai
- School of Electrical Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Michael Margaliot
- School of Electrical Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel.,Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Tamir Tuller
- Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv 69978, Israel.,Dept. of Biomedical Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
| |
Collapse
|
16
|
Goz E, Tuller T. Evidence of a Direct Evolutionary Selection for Strong Folding and Mutational Robustness Within HIV Coding Regions. J Comput Biol 2016; 23:641-50. [PMID: 27347769 DOI: 10.1089/cmb.2016.0052] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A large number of studies demonstrated the importance of different HIV RNA structural elements at all stages of the viral life cycle. Nevertheless, the significance of many of these structures is unknown, and plausibly new regions containing RNA structure-mediated regulatory signals remain to be identified. An important characteristic of genomic regions carrying functionally significant secondary structures is their mutational robustness, that is, the extent to which a sequence remains constant in spite of despite mutations in terms of its underlying secondary structure. Structural robustness to mutations is expected to be important in the case of functional RNA structures in viruses with high mutation rate; it may prevent fitness loss due to disruption of possibly functional conformations, pointing to the specific significance of the corresponding genomic region. In the current work, we perform a genome-wide computational analysis to detect signals of a direct evolutionary selection for strong folding and RNA structure-based mutational robustness within HIV coding sequences. We provide evidence that specific regions of HIV structural genes undergo an evolutionary selection for strong folding; in addition, we demonstrate that HIV Rev responsive element seems to undergo a direct evolutionary selection for increased secondary structure robustness to point mutations. We believe that our analysis may enable a better understanding of viral evolutionary dynamics at the RNA structural level and may benefit to practical efforts of engineering antiviral vaccines and novel therapeutic approaches.
Collapse
Affiliation(s)
- Eli Goz
- 1 Department of Biomedical Engineering, Tel-Aviv University , Ramat Aviv, Israel .,2 SynVaccine Ltd . Ramat Hachayal, Tel Aviv, Israel
| | - Tamir Tuller
- 1 Department of Biomedical Engineering, Tel-Aviv University , Ramat Aviv, Israel .,2 SynVaccine Ltd . Ramat Hachayal, Tel Aviv, Israel .,3 Sagol School of Neuroscience, Tel-Aviv University , Ramat Aviv, Israel
| |
Collapse
|