scholarly journals Regulation of Translation Initiation under Abiotic Stress Conditions in Plants: Is It a Conserved or Not so Conserved Process among Eukaryotes?

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Alfonso Muñoz ◽  
M. Mar Castellano
Keyword(s):  
Abiotic Stress ◽  
Translation Initiation ◽  
Translational Regulation ◽  
Gene Expression Regulation ◽  
Stress Conditions ◽  
Initiation Factors ◽  
Cellular Mrnas ◽  
Transcriptional Changes ◽  
Response To Stress ◽  
Control Translation

For years, the study of gene expression regulation of plants in response to stress conditions has been focused mainly on the analysis of transcriptional changes. However, the knowledge on translational regulation is very scarce in these organisms, despite in plants, as in the rest of the eukaryotes, translational regulation has been proven to play a pivotal role in the response to different stresses. Regulation of protein synthesis under abiotic stress was thought to be a conserved process, since, in general, both the translation factors and the translation process are basically similar in eukaryotes. However, this conservation is not so clear in plants as the knowledge of the mechanisms that control translation is very poor. Indeed, some of the basic regulators of translation initiation, well characterised in other systems, are still to be identified in plants. In this paper we will focus on both the regulation of different initiation factors and the mechanisms that cellular mRNAs use to bypass the translational repression established under abiotic stresses. For this purpose, we will review the knowledge from different eukaryotes but paying special attention to the information that has been recently published in plants.

scholarly journals Role of CDK1 in Translational Regulation in the M-Phase

2020 ◽  
Author(s):  
Jaroslav Kalous ◽  
Denisa Jansova ◽  
Andrej Susor
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Translational Regulation ◽  
Gene Expression Regulation ◽  
Translational Initiation ◽  
Initiation Factors ◽  
Cellular Events ◽  
M Phase ◽  
Mitosis And Meiosis

Cyclin dependent kinase 1 (CDK1) has been primarily identified as a key cell cycle regulator in both mitosis and meiosis. Recently, an extramitotic function of CDK1 emerged when evidence was found that CDK1 is involved in many cellular events that are essential for cell proliferation and survival. In this review we summarize the involvement of active CDK1 in the initiation and elongation steps of protein synthesis in eukaryotes. During its activation CDK1 influences the initiation of protein synthesis, promotes the activity of specific translational initiation factors and affects the functioning of a subset of elongation factors. Our review provides insights into gene expression regulation during the transcriptionally silent cell cycle/M-phase and describes quantitative and qualitative translational changes based on the extramitotic role of the cell cycle master regulator CDK1, to optimize temporal synthesis of proteins to sustain division-related processes: mitosis and cytokinesis.

scholarly journals Bacterial tRNA 2′-O-methylation is dynamically regulated under stress conditions and modulates innate immune response

2020 ◽  
Vol 48 (22) ◽  
pp. 12833-12844
Author(s):  
Adeline Galvanin ◽  
Lea-Marie Vogt ◽  
Antonia Grober ◽  
Isabel Freund ◽  
Lilia Ayadi ◽  
...  
Keyword(s):  
Gene Expression Regulation ◽  
Current Knowledge ◽  
Protein Translation ◽  
Stress Conditions ◽  
Transcriptional Level ◽  
Trna Modification ◽  
Rna Modifications ◽  
Swarming Motility ◽  
E Coli ◽  
Response To Stress

Abstract RNA modifications are a well-recognized way of gene expression regulation at the post-transcriptional level. Despite the importance of this level of regulation, current knowledge on modulation of tRNA modification status in response to stress conditions is far from being complete. While it is widely accepted that tRNA modifications are rather dynamic, such variations are mostly assessed in terms of total tRNA, with only a few instances where changes could be traced to single isoacceptor species. Using Escherichia coli as a model system, we explored stress-induced modulation of 2′-O-methylations in tRNAs by RiboMethSeq. This analysis and orthogonal analytical measurements by LC-MS show substantial, but not uniform, increase of the Gm18 level in selected tRNAs under mild bacteriostatic antibiotic stress, while other Nm modifications remain relatively constant. The absence of Gm18 modification in tRNAs leads to moderate alterations in E. coli mRNA transcriptome, but does not affect polysomal association of mRNAs. Interestingly, the subset of motility/chemiotaxis genes is significantly overexpressed in ΔTrmH mutant, this corroborates with increased swarming motility of the mutant strain. The stress-induced increase of tRNA Gm18 level, in turn, reduced immunostimulation properties of bacterial tRNAs, which is concordant with the previous observation that Gm18 is a suppressor of Toll-like receptor 7 (TLR7)-mediated interferon release. This documents an effect of stress induced modulation of tRNA modification that acts outside protein translation.

scholarly journals Translation Initiation Factors eIF3 and HCR1 Control Translation Termination and Stop Codon Read-Through in Yeast Cells

PLoS Genetics ◽  
2013 ◽  
Vol 9 (11) ◽  
pp. e1003962 ◽  
Author(s):  
Petra Beznosková ◽  
Lucie Cuchalová ◽  
Susan Wagner ◽  
Christopher J. Shoemaker ◽  
Stanislava Gunišová ◽  
...  
Keyword(s):  
Translation Initiation ◽  
Stop Codon ◽  
Translation Termination ◽  
Yeast Cells ◽  
Initiation Factors ◽  
Translation Initiation Factors ◽  
Control Translation

scholarly journals Assembly of 48S Translation Initiation Complexesfrom Purified Components with mRNAs That Have Some Base Pairingwithin Their 5′ UntranslatedRegions

2003 ◽  
Vol 23 (24) ◽  
pp. 8925-8933 ◽  
Author(s):  
Sergei E. Dmitriev ◽  
Ilya M. Terenin ◽  
Yan E. Dunaevsky ◽  
William C. Merrick ◽  
Ivan N. Shatsky
Keyword(s):  
Translation Initiation ◽  
Mammalian Cells ◽  
Ribosomal Subunit ◽  
Initiation Factor ◽  
Beta Globin ◽  
Globin Mrna ◽  
Initiation Factors ◽  
40S Ribosomal Subunit ◽  
Cellular Mrnas ◽  
Actin Mrna

ABSTRACT The reconstitution of translation initiation complexes from purified components is a reliable approach to determine the complete set of essential canonical initiation factors and auxiliary proteins required for the 40S ribosomal subunit to locate the initiation codon on individual mRNAs. Until now, it has been successful mostly for formation of 48S translation initiation complexes with viral IRES elements. Among cap-dependent mRNAs, only globin mRNAs and transcripts with artificial 5′ leaders were amenable to this assembly. Here, with modified conditions for the reconstitution, 48S complexes have been successfully assembled with the 5′ UTR of beta-actin mRNA (84 nucleotides) and the tripartite leader of adenovirus RNAs (232 nucleotides), though the latter has been able to use only the scanning rather then the shunting model of translation initiation with canonical initiation factors. We show that initiation factor 4B is essential for mRNAs that have even a rather moderate base pairing within their 5′ UTRs (with the cumulative stability of the secondary structure within the entire 5′ UTR < −13 kcal/mol) and not essential for beta-globin mRNA. A recombinant eIF4B poorly substitutes for the native factor. The 5′ UTRs with base-paired G residues reveal a very sharp dependence on the eIF4B concentration to form the 48S complex. The data suggest that even small variations in concentration or activity of eIF4B in mammalian cells may differentially affect the translation of different classes of cap-dependent cellular mRNAs.

scholarly journals Hijacking the translation apparatus by RNA viruses

2002 ◽  
Vol 158 (3) ◽  
pp. 395-399 ◽  
Author(s):  
Martin Bushell ◽  
Peter Sarnow
Keyword(s):  
Host Cell ◽  
Translation Initiation ◽  
Rna Viruses ◽  
Viral Mrnas ◽  
Viral Genomes ◽  
Initiation Factors ◽  
Translation Initiation Factors ◽  
Translation Apparatus ◽  
Cellular Mrnas ◽  
Successful Amplification

As invading viruses do not harbor functional ribosomes in their virions, successful amplification of the viral genomes requires that viral mRNAs compete with cellular mRNAs for the host cell translation apparatus. Several RNA viruses have evolved remarkable strategies to recruit the host translation initiation factors required for the first steps in translation initiation by host cell mRNAs. This review describes the ways that three families of RNA viruses effectively usurp limiting translation initiation factors from the host.

Takeover of host ribosomes by divergent IRES elements

2005 ◽  
Vol 33 (6) ◽  
pp. 1479-1482 ◽  
Author(s):  
P. Sarnow ◽  
R.C. Cevallos ◽  
E. Jan
Keyword(s):  
Translation Initiation ◽  
Viral Gene ◽  
Viral Mrnas ◽  
Internal Ribosome Entry ◽  
Eukaryotic Translation ◽  
Viral Genomes ◽  
Initiation Factors ◽  
Translation Initiation Factors ◽  
Cellular Mrnas ◽  
Eukaryotic Translation Initiation Factors

The ribosome is the macromolecular machinery in the host cell for which all viruses have to compete. Early in infection, the viral mRNAs have to compete with the host for both the ribosomes and for the limited pool of eukaryotic initiation factors that are needed to facilitate the recruitment of ribosomes to both viral and cellular mRNAs. To circumvent this competition, certain viruses have evolved to recruit ribosomes to IRESs (internal ribosome entry sites), highly specialized RNA elements that are located at the 5′-end of the viral genomes. Here, we discuss how divergent IRES elements can recruit ribosomes and start protein synthesis with only a minimal set of eukaryotic translation initiation factors, and how this mode of translation initiation aids viral gene amplification during early onset of innate immune responses.

scholarly journals Eukaryotic aspects of translation initiation brought into focus

2017 ◽  
Vol 372 (1716) ◽  
pp. 20160186 ◽  
Author(s):  
Christopher H. S. Aylett ◽  
Nenad Ban
Keyword(s):  
Translation Initiation ◽  
Structural Information ◽  
Start Codon ◽  
Translation Regulation ◽  
Initiation Factors ◽  
Codon Recognition ◽  
Initiation Of Translation ◽  
Control Translation ◽  
Additional Level ◽  
Subunit Joining

In all organisms, mRNA-directed protein synthesis is catalysed by ribosomes. Although the basic aspects of translation are preserved in all kingdoms of life, important differences are found in the process of translation initiation, which is rate-limiting and the most important step for translation regulation. While great strides had been taken towards a complete structural understanding of the initiation of translation in eubacteria, our understanding of the eukaryotic process, which includes numerous eukaryotic-specific initiation factors, was until recently limited owing to a lack of structural information. In this review, we discuss recent results in the field that provide an increasingly complete molecular description of the eukaryotic initiation process. The structural snapshots obtained using a range of methods now provide insights into the architecture of the initiation complex, start-codon recognition by the initiator tRNA and the process of subunit joining. Future advances will require both higher-resolution insights into previously characterized complexes and mapping of initiation factors that control translation on an additional level by interacting only peripherally or transiently with ribosomal subunits. This article is part of the themed issue ‘Perspectives on the ribosome’.

scholarly journals Transposable elements contribute to activation of maize genes in response to abiotic stress

2014 ◽  
Author(s):  
Irina Makarevitch ◽  
Amanda J Waters ◽  
Patrick T West ◽  
Michelle C Stitzer ◽  
Jeffrey Ross-Ibarra ◽  
...  
Keyword(s):  
Gene Expression ◽  
Abiotic Stress ◽  
Transposable Elements ◽  
Environmental Changes ◽  
Stress Conditions ◽  
Gene Expression Response ◽  
Regulatory Variation ◽  
Ideal System ◽  
Response To Stress ◽  
Regulated Gene Expression

Transposable elements (TEs) account for a large portion of the genome in many eukaryotic species. Despite their reputation as "junk" DNA or genomic parasites deleterious for the host, TEs have complex interactions with host genes and the potential to contribute to regulatory variation in gene expression. It has been hypothesized that TEs and genes they insert near may be transcriptionally activated in response to stress conditions. The maize genome, with many different types of TEs interspersed with genes, provides an ideal system to study the genome-wide influence of TEs on gene regulation. To analyze the magnitude of the TE effect on gene expression response to environmental changes, we profiled gene and TE transcript levels in maize seedlings exposed to a number of abiotic stresses. Many genes exhibit up- or down-regulation in response to these stress conditions. The analysis of TE families inserted within upstream regions of up-regulated genes revealed that between four and nine different TE families are associated with up-regulated gene expression in each of these stress conditions, affecting up to 20% of the genes up-regulated in response to abiotic stress and as many as 33% of genes that are only expressed in response to stress. Expression of many of these same TE families also responds to the same stress conditions. The analysis of the stress- induced transcripts and proximity of the transposon to the gene suggests that these TEs may provide local enhancer activities that stimulate stress-responsive gene expression. Our data on allelic variation for insertions of several of these TEs show strong correlation between the presence of TE insertions and stress-responsive up-regulation of gene expression. Our findings suggest that TEs provide an important source of allelic regulatory variation in gene response to abiotic stress in maize.

scholarly journals Established and Emerging Regulatory Roles of Eukaryotic Translation Initiation Factor 5B (eIF5B)

2021 ◽  
Vol 12 ◽  
Author(s):  
Prakash Amruth Raj Chukka ◽  
Stacey D. Wetmore ◽  
Nehal Thakor
Keyword(s):  
Translation Initiation ◽  
Translational Control ◽  
Translational Regulation ◽  
Eukaryotic Cell ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Eukaryotic Translation ◽  
Cellular Mrnas ◽  
Eukaryotic Translation Initiation ◽  
Initiation Stage

Translational control (TC) is one the crucial steps that dictate gene expression and alter the outcome of physiological process like programmed cell death, metabolism, and proliferation in a eukaryotic cell. TC occurs mainly at the translation initiation stage. The initiation factor eIF5B tightly regulates global translation initiation and facilitates the expression of a subset of proteins involved in proliferation, inhibition of apoptosis, and immunosuppression under stress conditions. eIF5B enhances the expression of these survival proteins to allow cancer cells to metastasize and resist chemotherapy. Using eIF5B as a biomarker or drug target could help with diagnosis and improved prognosis, respectively. To achieve these goals, it is crucial to understand the role of eIF5B in translational regulation. This review recapitulates eIF5B’s regulatory roles in the translation initiation of viral mRNA as well as the cellular mRNAs in cancer and stressed eukaryotic cells.

scholarly journals Translational Control of Canonical and Non-Canonical Translation Initiation Factors at the Sea Urchin Egg to Embryo Transition

2019 ◽  
Vol 20 (3) ◽  
pp. 626
Author(s):  
Héloïse Chassé ◽  
Sandrine Boulben ◽  
Patrick Cormier ◽  
Julia Morales
Keyword(s):  
Early Development ◽  
Sea Urchin ◽  
Translation Initiation ◽  
Translational Control ◽  
Translational Regulation ◽  
Sea Urchins ◽  
Embryonic Cell ◽  
Scaffolding Protein ◽  
Initiation Factors ◽  
The Impact

Sea urchin early development is a powerful model to study translational regulation under physiological conditions. Fertilization triggers an activation of the translation machinery responsible for the increase of protein synthesis necessary for the completion of the first embryonic cell cycles. The cap-binding protein eIF4E, the helicase eIF4A and the large scaffolding protein eIF4G are assembled upon fertilization to form an initiation complex on mRNAs involved in cap-dependent translation initiation. The presence of these proteins in unfertilized and fertilized eggs has already been demonstrated, however data concerning the translational status of translation factors are still scarce. Using polysome fractionation, we analyzed the impact of fertilization on the recruitment of mRNAs encoding initiation factors. Strikingly, whereas the mRNAs coding eIF4E, eIF4A, and eIF4G were not recruited into polysomes at 1 h post-fertilization, mRNAs for eIF4B and for non-canonical initiation factors such as DAP5, eIF4E2, eIF4E3, or hnRNP Q, are recruited and are differentially sensitive to the activation state of the mechanistic target of rapamycin (mTOR) pathway. We discuss our results suggesting alternative translation initiation in the context of the early development of sea urchins.

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