scholarly journals NMD: a multifaceted response to premature translational termination

2012 ◽  
Vol 13 (11) ◽  
pp. 700-712 ◽  
Author(s):  
Stephanie Kervestin ◽  
Allan Jacobson
Keyword(s):  
Translational Termination

scholarly journals Insights into Translational Termination from Crystal Structures of the 70S Ribosome Bound to Release Factor

2010 ◽  
Vol 98 (3) ◽  
pp. 260a
Author(s):  
Hong Jin ◽  
Albert Weixlbaumer ◽  
Cajetan Neubauer ◽  
Rebecca Voorhees ◽  
Sabine Petry ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Release Factor ◽  
70S Ribosome ◽  
Translational Termination

scholarly journals Titration and Conditional Knockdown of the prfB Gene in Escherichia coli: Effects on Growth and Overproduction of the Recombinant Mammalian Selenoprotein Thioredoxin Reductase

2006 ◽  
Vol 73 (2) ◽  
pp. 432-441 ◽  
Author(s):  
Olle Rengby ◽  
Elias S. J. Arnér
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Essential Gene ◽  
Thioredoxin Reductase ◽  
Lower Growth ◽  
E Coli ◽  
Native Promoter ◽  
Lower Growth Rate ◽  
The Cost ◽  
Translational Termination

ABSTRACT Release factor 2 (RF2), encoded by the prfB gene in Escherichia coli, catalyzes translational termination at UGA and UAA codons. Termination at UGA competes with selenocysteine (Sec) incorporation at Sec-dedicated UGA codons, and RF2 thereby counteracts expression of selenoproteins. prfB is an essential gene in E. coli and can therefore not be removed in order to increase yield of recombinant selenoproteins. We therefore constructed an E. coli strain with the endogenous chromosomal promoter of prfB replaced with the titratable PBAD promoter. Knockdown of prfB expression gave a bacteriostatic effect, while two- to sevenfold overexpression of RF2 resulted in a slightly lowered growth rate in late exponential phase. In a turbidostatic fermentor system the simultaneous impact of prfB knockdown on growth and recombinant selenoprotein expression was subsequently studied, using production of mammalian thioredoxin reductase as model system. This showed that lowering the levels of RF2 correlated directly with increasing Sec incorporation specificity, while also affecting total selenoprotein yield concomitant with a lower growth rate. This study thus demonstrates that expression of prfB can be titrated through targeted exchange of the native promoter with a PBAD-promoter and that knockdown of RF2 can result in almost full efficiency of Sec incorporation at the cost of lower total selenoprotein yield.

Translational termination efficiency in both bacteria and mammals is regulated by the base following the stop codon

1995 ◽  
Vol 73 (11-12) ◽  
pp. 1095-1103 ◽  
Author(s):  
Warren P. Tate ◽  
Elizabeth S. Poole ◽  
Julie A. Horsfield ◽  
Sally A. Mannering ◽  
Chris M. Brown ◽  
...  
Keyword(s):  
Stop Codon ◽  
Stop Signal ◽  
Physical Contact ◽  
Release Factor ◽  
Wide Range ◽  
Highly Expressed Genes ◽  
Peptidyltransferase Center ◽  
A Site ◽  
Translational Termination

The translational stop signal and polypeptide release factor (RF) complexed with Escherichia coli ribosomes have been shown to be in close physical contact by site-directed photochemical cross-linking experiments. The RF has a protease-sensitive site in a highly conserved exposed loop that is proposed to interact with the peptidyltransferase center of the ribosome. Loss of peptidyl–tRNA hydrolysis activity and enhanced codon–ribosome binding by the cleaved RF is consistent with a model whereby the RF spans the decoding and peptidyltransferase centers of the ribosome with domains of the RF linked by conformational coupling. The cross-link between the stop signal and RF at the ribosomal decoding site is influenced by the base following the termination codon. This base determines the efficiency with which the stop signal is decoded by the RF in both mammalian and bacterial systems in vivo. The wide range of efficiencies correlates with the frequency with which the signals occur at natural termination sites, with rarely used weak signals often found at recoding sites and strong signals found in highly expressed genes. Stop signals are found at some recoding sites in viruses where −1 frame-shifting occurs, but the generally accepted mechanism of simultaneous slippage from the A and P sites does not explain their presence here. The HIV-1 gag-pol −1 frame shifting site has been used to show that stop signals significantly influence frame-shifting efficiency on prokaryotic ribosomes by a RF-mediated mechanism. These data can be explained by an E/P site simultaneous slippage mechanism whereby the stop codon actually enters the ribosomal A site and can influence the event.Key words: translational stop signal, decoding, release factor, frame-shifting.

scholarly journals MISTERMINATE Mechanistically Links Mitochondrial Dysfunction with Proteostasis Failure

2019 ◽  
Author(s):  
Zhihao Wu ◽  
Ishaq Tantray ◽  
Junghyun Lim ◽  
Songjie Chen ◽  
Yu Li ◽  
...  
Keyword(s):  
Amino Acids ◽  
Mitochondrial Dysfunction ◽  
Complex I ◽  
Mammalian Cells ◽  
Protein C ◽  
Stop Codon ◽  
Translation Termination ◽  
Disease Model ◽  
C Terminus ◽  
Translational Termination

SUMMARYMitochondrial dysfunction and proteostasis failure frequently coexist as hallmarks of neurodegenerative disease. How these pathologies are related is not well understood. Here we describe a phenomenon termed MISTERMINATE (mitochondrial stress-induced translational termination impairment and protein carboxyl terminal extension), which mechanistically links mitochondrial dysfunction with proteostasis failure. We show that mitochondrial dysfunction impairs translational termination of nuclear-encoded mitochondrial mRNAs including complex-I 30kD subunit (C-I30) mRNA, occurring on mitochondrial surface in Drosophila and mammalian cells. Ribosomes stalled at the normal stop codon continue to add to the C-terminus of C-I30 certain amino acids non-coded by mRNA template. C-terminally-extended C-I30 is toxic when assembled into C-I and forms aggregates in the cytosol. Enhancing co-translational quality control prevents C-I30 C-terminal extension and rescues mitochondrial and neuromuscular degeneration in a Parkinson’s disease model. These findings emphasize the importance of efficient translation termination and reveal unexpected link between mitochondrial health and proteome homeostasis mediated by MISTERMINATE.

scholarly journals Unusual ciliate-specific codons in Tetrahymena mRNAs are translated correctly in a rabbit reticulocyte lysate supplemented with a subcellular fraction from Tetrahymena

1987 ◽  
Vol 244 (2) ◽  
pp. 331-335 ◽  
Author(s):  
P H Andreasen ◽  
H Dreisig ◽  
K Kristiansen
Keyword(s):  
Codon Usage ◽  
Genetic Code ◽  
Subcellular Fraction ◽  
Tetrahymena Thermophila ◽  
Rabbit Reticulocyte Lysate ◽  
Reading Frame ◽  
Universal Genetic Code ◽  
Reticulocyte Lysate ◽  
Translational Termination

The codon usage of Tetrahymena thermophila and other ciliates deviates from the ‘universal genetic code’ in that UAA and probably UAG are not translational termination signals but code for glutamine. Therefore, translation in vitro of mRNA from Tetrahymena in a reticulocyte lysate is prematurely terminated if a UAA or UAG triplet is present in the reading frame of the mRNA. We show that the addition of a subcellular fraction from Tetrahymena thermophila enables a rabbit reticulocyte lysate to translate Tetrahymena mRNAs into full-sized proteins. The activity of the subcellular fraction is shown to depend on the combined function of a protein component(s) and a tRNA(s). The subcellular fraction is easily prepared and its usefulness for the identification of isolated mRNAs from Tetrahymena by their translation products in vitro is demonstrated.

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