scholarly journals Functional mapping of the translation-dependent instability element of yeast MATalpha1 mRNA.

1996 ◽  
Vol 16 (7) ◽  
pp. 3833-3843 ◽  
Author(s):  
A N Hennigan ◽  
A Jacobson
Keyword(s):  
Stability Boundary ◽  
Mrna Translation ◽  
Rare Codon ◽  
Molecular Evidence ◽  
Wild Type ◽  
Coding Region ◽  
Sequence Element ◽  
Protein Coding ◽  
Cis Acting ◽  
Mrna Stabilization

The determinants of mRNA stability include specific cis-acting destabilizing sequences located within mRNA coding and noncoding regions. We have developed an approach for mapping coding-region instability sequences in unstable yeast mRNAs that exploits the link between mRNA translation and turnover and the dependence of nonsense-mediated mRNA decay on the activity of the UPF1 gene product. This approach, which involves the systematic insertion of in-frame translational termination codons into the coding sequence of a gene of interest in a upf1delta strain, differs significantly from conventional methods for mapping cis-acting elements in that it causes minimal perturbations to overall mRNA structure. Using the previously characterized MATalpha1 mRNA as a model, we have accurately localized its 65-nucleotide instability element (IE) within the protein coding region. Termination of translation 5' to this element stabilized the MATalpha1 mRNA two- to threefold relative to wild-type transcripts. Translation through the element was sufficient to restore an unstable decay phenotype, while internal termination resulted in different extents of mRNA stabilization dependent on the precise location of ribosome stalling. Detailed mutagenesis of the element's rare-codon/AU-rich sequence boundary revealed that the destabilizing activity of the MATalpha1 IE is observed when the terminal codon of the element's rare-codon interval is translated. This region of stability transition corresponds precisely to a MATalpha1 IE sequence previously shown to be complementary to 18S rRNA. Deletion of three nucleotides 3' to this sequence shifted the stability boundary one codon 5' to its wild-type location. Conversely, constructs containing an additional three nucleotides at this same location shifted the transition downstream by an equivalent sequence distance. Our results suggest a model in which the triggering of MATalpha1 mRNA destabilization results from establishment of an interaction between translating ribosomes and a downstream sequence element. Furthermore, our data provide direct molecular evidence for a relationship between mRNA turnover and mRNA translation.

scholarly journals The Infectivities of Turnip Yellow Mosaic Virus Genomes with Altered tRNA Mimicry Are Not Dependent on Compensating Mutations in the Viral Replication Protein

2000 ◽  
Vol 74 (18) ◽  
pp. 8368-8375 ◽  
Author(s):  
Sergei A. Filichkin ◽  
Kay L. Bransom ◽  
Joel B. Goodwin ◽  
Theo W. Dreher
Keyword(s):  
Mosaic Virus ◽  
Replication Protein ◽  
Yellow Mosaic Virus ◽  
Turnip Yellow Mosaic Virus ◽  
Wild Type ◽  
Coding Region ◽  
Protein Coding ◽  
Complete Sequencing ◽  
Strand Initiation ◽  
Virus Genomes

ABSTRACT Five highly infectious turnip yellow mosaic virus (TYMV) genomes with sequence changes in their 3′-terminal regions that result in altered aminoacylation and eEF1A binding have been studied. These genomes were derived from cloned parental RNAs of low infectivity by sequential passaging in plants. Three of these genomes that are incapable of aminoacylation have been reported previously (J. B. Goodwin, J. M. Skuzeski, and T. W. Dreher, Virology 230:113–124, 1997). We now demonstrate by subcloning the 3′ untranslated regions into wild-type TYMV RNA that the high infectivities and replication rates of these genomes compared to their progenitors are mostly due to a small number of mutations acquired in the 3′ tRNA-like structure during passaging. Mutations in other parts of the genome, including the replication protein coding region, are not required for high infectivity but probably do play a role in optimizing viral amplification and spread in plants. Two other TYMV RNA variants of suboptimal infectivities, one that accepts methionine instead of the usual valine and one that interacts less tightly with eEF1A, were sequentially passaged to produce highly infectious genomes. The improved infectivities of these RNAs were not associated with increased replication in protoplasts, and no mutations were acquired in their 3′ tRNA-like structures. Complete sequencing of one genome identified two mutations that result in amino acid changes in the movement protein gene, suggesting that improved infectivity may be a function of improved viral dissemination in plants. Our results show that the wild-type TYMV replication proteins are able to amplify genomes with 3′ termini of variable sequence and tRNA mimicry. These and previous results have led to a model in which the binding of eEF1A to the 3′ end to antagonize minus-strand initiation is a major role of the tRNA-like structure.

scholarly journals Molecular Evidence that the Extracellular Cutinase Pbc1 Is Required for Pathogenicity of Pyrenopeziza brassicae on Oilseed Rape

2003 ◽  
Vol 16 (6) ◽  
pp. 545-552 ◽  
Author(s):  
Donghui Li ◽  
Alison M. Ashby ◽  
Keith Johnstone
Keyword(s):  
Oilseed Rape ◽  
Single Copy ◽  
Leaf Spot Disease ◽  
Molecular Evidence ◽  
Wild Type ◽  
In Planta ◽  
Coding Region ◽  
Causal Organism ◽  
Type Gene ◽  
Culture Supernatants

Recent evidence has suggested that cutinase is required for cuticular penetration and, therefore, is essential for pathogenicity of Pyrenopeziza brassicae, the causal organism of light leaf spot disease of oilseed rape and other brassicas. In order to acquire molecular evidence for the role of cutinase in pathogenesis, the single-copy P. brassicae cutinase gene Pbc1 was disrupted by a transformation-mediated approach. Southern hybridization analysis revealed that in one mutant, NH10-1224, the disruption was due to a tandem insertion of two copies of the disruption vector into the 5′ coding region of Pbc1. In contrast to the wild type, no expression of Pbc1 was detected during in planta growth or in cutin-induced mycelium of NH10-1224 and no cutinase activity was detected in culture supernatants from NH10-1224 using pnitrophenyl butyrate as substrate. Scanning electron microscopy of Brassica napus cotyledons infected with wild-type P. brassicae confirmed that entry into the host is by direct penetration of the cuticle. In contrast, the cutinase-deficient mutant NH10-1224 failed to penetrate the cuticular layer and was unable to develop disease symptoms. This evidence is consistent with the hypothesis that Pbc1 is required for P. brassicae to penetrate the plant cuticle. Demonstration that complementation of NH10-1224 with the Pbc1 wild-type gene restores both cutinase activity and pathogenicity will be required to definitively establish that cutinase is required for successful pathogenesis of brassicas by P. brassicae.

Transcription control region within the protein-coding portion of adenovirus E1A genes

1984 ◽  
Vol 4 (7) ◽  
pp. 1293-1305
Author(s):  
T F Osborne ◽  
D N Arvidson ◽  
E S Tyau ◽  
M Dunsworth-Browne ◽  
A J Berk
Keyword(s):  
Control Region ◽  
Adenovirus Type ◽  
Coding Region ◽  
Transcription Control ◽  
Protein Coding ◽  
Single Base ◽  
Cis Acting ◽  
Single Base Deletion ◽  
Adenovirus Type 5 ◽  
E1a Protein

A single-base deletion within the protein-coding region of the adenovirus type 5 early region 1A (E1A) genes, 399 bases downstream from the transcription start site, depresses transcription to 2% of the wild-type rate. Complementation studies demonstrated that this was due to two effects of the mutation: first, inactivation of an E1A protein, causing a reduction by a factor of 5; second, a defect which acts in cis to depress E1A mRNA and nuclear RNA concentrations by a factor of 10. A larger deletion within the protein-coding region of E1A which overlaps the single-base deletion produces the same phenotype. In contrast, a linker insertion which results in a similar truncated E1A protein does not produce the cis-acting defect in E1A transcription. These results demonstrate that a critical cis-acting transcription control region occurs within the protein coding sequence in adenovirus type 5 E1A. The single-base deletion occurs in a sequence which shows extensive homology with a sequence from the enhancer regions of simian virus 40 and polyomavirus. This region is not required for E1A transcription during the late phase of infection.

scholarly journals Transcription control region within the protein-coding portion of adenovirus E1A genes.

1984 ◽  
Vol 4 (7) ◽  
pp. 1293-1305 ◽  
Author(s):  
T F Osborne ◽  
D N Arvidson ◽  
E S Tyau ◽  
M Dunsworth-Browne ◽  
A J Berk
Keyword(s):  
Control Region ◽  
Adenovirus Type ◽  
Coding Region ◽  
Transcription Control ◽  
Protein Coding ◽  
Single Base ◽  
Cis Acting ◽  
Single Base Deletion ◽  
Adenovirus Type 5 ◽  
E1a Protein

A single-base deletion within the protein-coding region of the adenovirus type 5 early region 1A (E1A) genes, 399 bases downstream from the transcription start site, depresses transcription to 2% of the wild-type rate. Complementation studies demonstrated that this was due to two effects of the mutation: first, inactivation of an E1A protein, causing a reduction by a factor of 5; second, a defect which acts in cis to depress E1A mRNA and nuclear RNA concentrations by a factor of 10. A larger deletion within the protein-coding region of E1A which overlaps the single-base deletion produces the same phenotype. In contrast, a linker insertion which results in a similar truncated E1A protein does not produce the cis-acting defect in E1A transcription. These results demonstrate that a critical cis-acting transcription control region occurs within the protein coding sequence in adenovirus type 5 E1A. The single-base deletion occurs in a sequence which shows extensive homology with a sequence from the enhancer regions of simian virus 40 and polyomavirus. This region is not required for E1A transcription during the late phase of infection.

scholarly journals Genetic recombination in wild-type poliovirus

2002 ◽  
Vol 83 (12) ◽  
pp. 3103-3110 ◽  
Author(s):  
George Dahourou ◽  
Sophie Guillot ◽  
Olivier Le Gall ◽  
Radu Crainic
Keyword(s):  
Capsid Protein ◽  
Genetic Recombination ◽  
Paralytic Poliomyelitis ◽  
Wild Type ◽  
Coding Region ◽  
Phylogenic Tree ◽  
Protein Coding ◽  
Parallel Application ◽  
Specific Nucleotide Sequence ◽  
Capsid Protein Vp1

Poliovirus isolates were screened for recombinants by combined analysis of two distant polymorphic segments of the poliovirus genome (one in the capsid and the other in the polymerase-coding region). Using a restriction fragment length polymorphism (RFLP) assay, a high number of recombinant genomes was found among vaccine-derived strains excreted by poliovirus vaccine vaccinees or vaccine-associated paralytic poliomyelitis cases. Some of these subjects carried a wild-type poliovirus (non-vaccine-specific) nucleotide sequence in the 3′ part of the genome. Using a similar approach, a collection of wild-type poliovirus strains isolated in South India between 1985 and 1993 was screened for recombinants. Genotypes were defined by the parallel application of RFLP assays and genomic sequencing of the capsid protein VP1 and the 3D polymerase polypeptide. Analyses revealed several instances where the position of an isolate on the phylogenic tree for the capsid protein-coding segment did not agree with its position on the tree for the polymerase-coding region. In this way, several wild-type/wild-type and wild-type/vaccine recombinants could be identified, indicating that recombination is encountered commonly in the natural evolution of poliovirus strains.

Selection on Rapidly Evolving Proteins in the Arabidopsis Genome

Genetics ◽  
2003 ◽  
Vol 163 (2) ◽  
pp. 723-733 ◽  
Author(s):  
Marianne Barrier ◽  
Carlos D Bustamante ◽  
Jiaye Yu ◽  
Michael D Purugganan
Keyword(s):  
Expressed Sequence Tag ◽  
Amino Acid Replacement ◽  
Adaptive Divergence ◽  
Coding Region ◽  
Protein Coding ◽  
Hierarchical Bayesian Analysis ◽  
Brassicaceae Species ◽  
Replacement Site ◽  
Orthologous Loci ◽  
Selection Intensities

Abstract Genes that have undergone positive or diversifying selection are likely to be associated with adaptive divergence between species. One indicator of adaptive selection at the molecular level is an excess of amino acid replacement fixed differences per replacement site relative to the number of synonymous fixed differences per synonymous site (ω = Ka/Ks). We used an evolutionary expressed sequence tag (EST) approach to estimate the distribution of ω among 304 orthologous loci between Arabidopsis thaliana and A. lyrata to identify genes potentially involved in the adaptive divergence between these two Brassicaceae species. We find that 14 of 304 genes (∼5%) have an estimated ω > 1 and are candidates for genes with increased selection intensities. Molecular population genetic analyses of 6 of these rapidly evolving protein loci indicate that, despite their high levels of between-species nonsynonymous divergence, these genes do not have elevated levels of intraspecific replacement polymorphisms compared to previously studied genes. A hierarchical Bayesian analysis of protein-coding region evolution within and between species also indicates that the selection intensities of these genes are elevated compared to previously studied A. thaliana nuclear loci.

scholarly journals Ionizing Radiation and Translation Control: A Link to Radiation Hormesis?

2020 ◽  
Vol 21 (18) ◽  
pp. 6650
Author(s):  
Usha Kabilan ◽  
Tyson E. Graber ◽  
Tommy Alain ◽  
Dmitry Klokov
Keyword(s):  
Protein Synthesis ◽  
Ionizing Radiation ◽  
Molecular Mechanisms ◽  
Low Dose ◽  
Mrna Translation ◽  
Cellular Responses ◽  
Translation Control ◽  
Cis Acting ◽  
Radiation Hormesis ◽  
Downstream Signaling

Protein synthesis, or mRNA translation, is one of the most energy-consuming functions in cells. Translation of mRNA into proteins is thus highly regulated by and integrated with upstream and downstream signaling pathways, dependent on various transacting proteins and cis-acting elements within the substrate mRNAs. Under conditions of stress, such as exposure to ionizing radiation, regulatory mechanisms reprogram protein synthesis to translate mRNAs encoding proteins that ensure proper cellular responses. Interestingly, beneficial responses to low-dose radiation exposure, known as radiation hormesis, have been described in several models, but the molecular mechanisms behind this phenomenon are largely unknown. In this review, we explore how differences in cellular responses to high- vs. low-dose ionizing radiation are realized through the modulation of molecular pathways with a particular emphasis on the regulation of mRNA translation control.

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