scholarly journals The radish Ogura fertility restorer impedes translation elongation along its cognate CMS-causing mRNA

2021 ◽  
Author(s):  
Chuande Wang ◽  
Lina Lezhneva ◽  
Nadège Arnal ◽  
Martine Quadrado ◽  
Hakim Mireau
Keyword(s):  
Mrna Translation ◽  
Pollen Sterility ◽  
Mitochondrial Genes ◽  
Genetic Interactions ◽  
Gene Control ◽  
Specific Inhibition ◽  
Fertility Restorer ◽  
Translation Elongation ◽  
Restorer Of Fertility ◽  
Fertility Restorers

AbstractThe control of mRNA translation has been increasingly recognized as a key regulatory step for gene control but clear examples in eukaryotes are still scarce. Nucleo-cytoplasmic male sterilities (CMS) represent ideal genetic models to dissect genetic interactions between the mitochondria and the nucleus in plants. This trait is determined by specific mitochondrial genes and is associated with a pollen sterility phenotype that can be suppressed by nuclear genes known as restorer-of-fertility (Rf) genes. In the study, we focused on the Ogura CMS system in rapeseed and showed that the suppression to male sterility by the PPR-B fertility restorer (also called Rfo) occurs through a specific inhibition of the translation of the mitochondria-encoded CMS-causing mRNA orf138. We also demonstrate that PPR-B binds within the coding sequence of orf138 and acts as a ribosome blocker to specifically impede translation elongation along the orf138 mRNA. Rfo is the first recognized fertility restorer shown to act this way. These observations will certainly facilitate the development of synthetic fertility restorers for CMS systems in which efficient natural Rfs are lacking.

scholarly journals The radish Ogura fertility restorer impedes translation elongation along its cognate CMS-causing mRNA

2021 ◽  
Vol 118 (35) ◽  
pp. e2105274118
Author(s):  
Chuande Wang ◽  
Lina Lezhneva ◽  
Nadège Arnal ◽  
Martine Quadrado ◽  
Hakim Mireau
Keyword(s):  
Messenger Rna ◽  
Mrna Translation ◽  
Pollen Sterility ◽  
Genetic Interactions ◽  
Gene Control ◽  
Fertility Restorer ◽  
Translation Elongation ◽  
Translation Inhibition ◽  
Restorer Of Fertility ◽  
Fertility Restorers

The control of messenger RNA (mRNA) translation has been increasingly recognized as a key regulatory step for gene control, but clear examples in eukaryotes are still scarce. Nucleo-cytoplasmic male sterilities (CMS) represent ideal genetic models to dissect genetic interactions between the mitochondria and the nucleus in plants. This trait is determined by specific mitochondrial genes and is associated with a pollen sterility phenotype that can be suppressed by nuclear genes known as restorer-of-fertility (Rf). In this study, we focused on the Ogura CMS system in rapeseed and showed that reversion to male sterility by the PPR-B fertility restorer (also called Rfo) occurs through a specific translation inhibition of the mitochondria-encoded CMS-causing mRNA orf138. We also demonstrate that PPR-B binds within the coding sequence of orf138 and acts as a ribosome blocker to specifically impede translation elongation along the orf138 mRNA. Rfo is the first recognized fertility restorer shown to act this way. These observations will certainly facilitate the development of synthetic fertility restorers for CMS systems in which efficient natural Rfs are lacking.

Marker-assisted identification of potential fertility restorers for the development of three-line hybrids in rice (Oryza sativa L.)

2020 ◽  
Vol 57 (3) ◽  
pp. 181-189
Author(s):  
Asma Majid ◽  
GA Parray ◽  
NR Sofi ◽  
Gazala H Khan ◽  
Showkat A Waza ◽  
...  
Keyword(s):  
Oryza Sativa L ◽  
Chromosome 1 ◽  
Limiting Factor ◽  
Kashmir Valley ◽  
Fertility Restorer ◽  
Yield And Quality ◽  
Restorer Genes ◽  
Increase Productivity ◽  
Fertility Restorers ◽  
Selection Of

Rice being a staple food crop of Kashmir valley, the focus is on enhancement of yield in order to meet the needs of ever-growing population.Identification of new parental lines is crucial for developing ecology-specific hybrids with ideal agronomic performance. Exploitation of heterosis in the form of hybrid rice technology can be one of the approaches to increase productivity in this crop, especially exploiting diversity among japonica lines can serve as an excellent route.A number of CMS lines suitable formountainous areas of Kashmir have been developed, however, the availability of promising restorer lines remains to be the major limitation for utilization of these lines.Identification of potential restorers acts as the main limiting factor for hybrid development in the Kashmir valley. Marker based screening for Rf3 and Rf4 fertility restorer genes can be helpful in rapid selection of restorer lines while dealing with the large quantity of genetic materials. In the present study, 100 rice germplasm were screened with the help of SSR markers, RM3148 and RM6100linked to Rf3 and Rf4 genes on chromosome 1 and 10, respectively. In total, 19 lines revealed the presence of both Rf3 and Rf4 genes. These lines amplified fertility restorer specific alleles for both the genes and may serve as potential restorers for obtaining heterotic rice hybrids. Further the germplasm lines were also evaluated for yield and quality traits.The present results would help in selection of suitable restorers along with preferred grain shape/size.

scholarly journals A Complementary Mechanism of Bacterial mRNA Translation Inhibition by Tetracyclines

2021 ◽  
Vol 12 ◽  
Author(s):  
Victor Barrenechea ◽  
Maryhory Vargas-Reyes ◽  
Miguel Quiliano ◽  
Pohl Milón
Keyword(s):  
Protein Synthesis ◽  
Translation Initiation ◽  
Ribosomal Subunit ◽  
Mrna Translation ◽  
Resistance Mechanisms ◽  
Dissociation Rate ◽  
Initiation Factor ◽  
Translation Elongation ◽  
Initiation Phase ◽  
Complementary Mechanism

Tetracycline has positively impacted human health as well as the farming and animal industries. Its extensive usage and versatility led to the spread of resistance mechanisms followed by the development of new variants of the antibiotic. Tetracyclines inhibit bacterial growth by impeding the binding of elongator tRNAs to the ribosome. However, a small number of reports indicated that Tetracyclines could also inhibit translation initiation, yet the molecular mechanism remained unknown. Here, we use biochemical and computational methods to study how Oxytetracycline (Otc), Demeclocycline (Dem), and Tigecycline (Tig) affect the translation initiation phase of protein synthesis. Our results show that all three Tetracyclines induce Initiation Factor IF3 to adopt a compact conformation on the 30S ribosomal subunit, similar to that induced by Initiation Factor IF1. This compaction was faster for Tig than Dem or Otc. Furthermore, all three tested tetracyclines affected IF1-bound 30S complexes. The dissociation rate constant of IF1 in early 30S complexes was 14-fold slower for Tig than Dem or Otc. Late 30S initiation complexes (30S pre-IC or IC) exhibited greater IF1 stabilization by Tig than for Dem and Otc. Tig and Otc delayed 50S joining to 30S initiation complexes (30S ICs). Remarkably, the presence of Tig considerably slowed the progression to translation elongation and retained IF1 in the resulting 70S initiation complex (70S IC). Molecular modeling of Tetracyclines bound to the 30S pre-IC and 30S IC indicated that the antibiotics binding site topography fluctuates along the initiation pathway. Mainly, 30S complexes show potential contacts between Dem or Tig with IF1, providing a structural rationale for the enhanced affinity of the antibiotics in the presence of the factor. Altogether, our data indicate that Tetracyclines inhibit translation initiation by allosterically perturbing the IF3 layout on the 30S, retaining IF1 during 70S IC formation, and slowing the transition toward translation elongation. Thus, this study describes a new complementary mechanism by which Tetracyclines may inhibit bacterial protein synthesis.

scholarly journals Inferring efficiency of translation initiation and elongation from ribosome profiling

2020 ◽  
Vol 48 (17) ◽  
pp. 9478-9490
Author(s):  
Juraj Szavits-Nossan ◽  
Luca Ciandrini
Keyword(s):  
Protein Synthesis ◽  
Mathematical Modelling ◽  
Translation Initiation ◽  
Mrna Translation ◽  
Elongation Rate ◽  
Ribosome Profiling ◽  
Translation Elongation ◽  
Recent Advances ◽  
Two Stages

Abstract One of the main goals of ribosome profiling is to quantify the rate of protein synthesis at the level of translation. Here, we develop a method for inferring translation elongation kinetics from ribosome profiling data using recent advances in mathematical modelling of mRNA translation. Our method distinguishes between the elongation rate intrinsic to the ribosome’s stepping cycle and the actual elongation rate that takes into account ribosome interference. This distinction allows us to quantify the extent of ribosomal collisions along the transcript and identify individual codons where ribosomal collisions are likely. When examining ribosome profiling in yeast, we observe that translation initiation and elongation are close to their optima and traffic is minimized at the beginning of the transcript to favour ribosome recruitment. However, we find many individual sites of congestion along the mRNAs where the probability of ribosome interference can reach $50\%$. Our work provides new measures of translation initiation and elongation efficiencies, emphasizing the importance of rating these two stages of translation separately.

scholarly journals Genetic evidence that different functional domains of the PET54 gene product facilitate expression of the mitochondrial genes COX1 and COX3 in Saccharomyces cerevisiae.

1991 ◽  
Vol 11 (5) ◽  
pp. 2399-2405 ◽  
Author(s):  
M L Valencik ◽  
J E McEwen
Keyword(s):  
Gene Expression ◽  
Gene Product ◽  
Rna Splicing ◽  
Rna Secondary Structure ◽  
Mitochondrial Gene ◽  
Mrna Translation ◽  
Mitochondrial Genes ◽  
Mitochondrial Gene Expression ◽  
Single Mechanism ◽  
Insertion Mutations

Expression of the yeast mitochondrial genes COX1 and COX3, which encode subunits I and III of cytochrome oxidase, respectively, is controlled by a common nuclear-encoded trans-acting factor. This protein, encoded by the PET54 gene, controls expression of COX1 at the level of RNA splicing and COX3 at the level of mRNA translation. While the steps of COX1 and COX3 gene expression affected by the PET54 gene product are different, it is possible that the PET54 protein is monofunctional and affects expression of each gene by a single mechanism, such as modulation of RNA secondary structure. The goal of this study was to address whether the PET54 protein is monofunctional or multifunctional with respect to its role in COX1 and COX3 gene expression. Ten insertion mutations, which each resulted in the in-frame addition of four amino acids within the PET54 polypeptide, were generated, and the resulting mutants were characterized for respiration phenotype and mitochondrial gene expression. Five of the ten mutants were respiration deficient. Two of these five mutants were defective in expression of COX3 but not in expression of COX1, while two other mutants had the opposite phenotype (primarily defective in expression of COX1). The fifth mutant was equally defective in expression of both genes. These results demonstrate that the two functions of PET54 are genetically separable and support the idea that the PET54 protein is multifunctional.

scholarly journals Protein synthesis rates and ribosome occupancies reveal determinants of translation elongation rates

2018 ◽  
Author(s):  
Andrea Riba ◽  
Noemi Di Nanni ◽  
Nitish Mittal ◽  
Erik Arhné ◽  
Alexander Schmidt ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Amino Acid Composition ◽  
Acid Composition ◽  
Translation Initiation ◽  
Mrna Translation ◽  
Elongation Rate ◽  
Translation Elongation ◽  
Lower Protein ◽  
Protein Output

AbstractAlthough protein synthesis dynamics has been studied both with theoretical models and by profiling ribosome footprints, the determinants of ribosome flux along open reading frames (ORFs) are not fully understood. Combining measurements of protein synthesis rate with ribosome footprinting data, we here inferred translation initiation and elongation rates for over a thousand ORFs in exponentially-growing wildtype yeast cells. We found that the amino acid composition of synthesized proteins is as important a determinant of translation elongation rate as parameters related to codon and tRNA adaptation. We did not find evidence of ribosome collisions curbing the protein output of yeast transcripts, either in high translation conditions associated with exponential growth, or in strains in which deletion of individual ribosomal protein genes leads to globally increased or decreased translation. Slow translation elongation is characteristic of RP-encoding transcripts, which have markedly lower protein output than other transcripts with equally high ribosome densities.Significance StatementAlthough sequencing of ribosome footprints has uncovered new aspects of mRNA translation, the determinants of ribosome flux remain incompletely understood. Combining ribosome footprint data with measurements of protein synthesis rates, we here inferred translation initiation and elongation rates for over a thousand ORFs in yeast strains with varying translation capacity. We found that the translation elongation rate varies up to ~20-fold among yeast transcripts, and is significantly correlated with the rate of translation initiation. Furthermore, the amino acid composition of synthesized proteins impacts the rate of translation elongation to the same extent as measures of codon and tRNA adaptation. Transcripts encoding ribosomal proteins are translated especially slow, having markedly lower protein output than other transcripts with equally high ribosome densities.

scholarly journals Wobble tRNA modification and hydrophilic amino acid patterns dictate protein fate

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesca Rapino ◽  
Zhaoli Zhou ◽  
Ana Maria Roncero Sanchez ◽  
Marc Joiret ◽  
Christian Seca ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Expression ◽  
Protein Aggregation ◽  
Critical Role ◽  
Mrna Translation ◽  
Trna Modification ◽  
Translation Elongation ◽  
Hydrophilic Amino Acid ◽  
Protein Output

AbstractRegulation of mRNA translation elongation impacts nascent protein synthesis and integrity and plays a critical role in disease establishment. Here, we investigate features linking regulation of codon-dependent translation elongation to protein expression and homeostasis. Using knockdown models of enzymes that catalyze the mcm5s2 wobble uridine tRNA modification (U34-enzymes), we show that gene codon content is necessary but not sufficient to predict protein fate. While translation defects upon perturbation of U34-enzymes are strictly dependent on codon content, the consequences on protein output are determined by other features. Specific hydrophilic motifs cause protein aggregation and degradation upon codon-dependent translation elongation defects. Accordingly, the combination of codon content and the presence of hydrophilic motifs define the proteome whose maintenance relies on U34-tRNA modification. Together, these results uncover the mechanism linking wobble tRNA modification to mRNA translation and aggregation to maintain proteome homeostasis.

scholarly journals iRQC, a surveillance pathway for 40S ribosomal quality control during mRNA translation initiation

2021 ◽  
Author(s):  
Danielle Marie Garshott ◽  
Heeseon An ◽  
Elayanambi Sundaramoorthy ◽  
Marilyn Leonard ◽  
Alison Vicary ◽  
...  
Keyword(s):  
Quality Control ◽  
Stress Response ◽  
Ribosomal Protein ◽  
Protein Degradation ◽  
Ubiquitin Ligase ◽  
Translation Initiation ◽  
Mrna Translation ◽  
Start Codon ◽  
Independent Manner ◽  
Translation Elongation

Since multiple ribosomes can engage a single mRNA, nonuniform ribosome progression can result in collisions. Ribosome collisions during translation elongation elicit a multifaceted ribosome-associated quality control (RQC) response. Despite advanced mechanistic understanding of translation initiation, a parallel RQC pathway that acts on collided preinitiation complexes has not been described. Here, we show that blocking progression of scanning or elongating ribosomes past the start codon triggers uS3 and uS5 ribosomal ubiquitylation. We demonstrate that conditions that activate the integrated stress response can also induce preinitiation complex collisions. The ubiquitin ligase, RNF10, and the deubiquitylating enzyme, USP10, are the key regulators of uS3 and uS5 ubiquitylation. Prolonged uS3 and uS5 ubiquitylation results in 40S, but not 60S, ribosomal protein degradation in an autophagy-independent manner. This study identifies a distinct arm in the RQC pathway, initiation RQC (iRQC), that acts on pervasive ribosome collisions during translation initiation to modulate translation activity and capacity.

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