Principles of stop-codon reading on the ribosome

Nature ◽  
2010 ◽  
Vol 465 (7300) ◽  
pp. 947-950 ◽  
Author(s):  
Johan Sund ◽  
Martin Andér ◽  
Johan Åqvist
Keyword(s):  
Stop Codon ◽  
Codon Reading

scholarly journals N 6-Methyladenosines in mRNAs reduce the accuracy of codon reading by transfer RNAs and peptide release factors

2021 ◽  
Vol 49 (5) ◽  
pp. 2684-2699
Author(s):  
Ka-Weng Ieong ◽  
Gabriele Indrisiunaite ◽  
Arjun Prabhakar ◽  
Joseph D Puglisi ◽  
Måns Ehrenberg
Keyword(s):  
Single Molecule ◽  
Stop Codon ◽  
Product Formation ◽  
Release Factors ◽  
Substrate Complex ◽  
Peptidyl Transfer ◽  
Enzyme Substrate ◽  
Peptide Release ◽  
Accuracy Ratio ◽  
Codon Reading

Abstract We used quench flow to study how N6-methylated adenosines (m6A) affect the accuracy ratio between kcat/Km (i.e. association rate constant (ka) times probability (Pp) of product formation after enzyme-substrate complex formation) for cognate and near-cognate substrate for mRNA reading by tRNAs and peptide release factors 1 and 2 (RFs) during translation with purified Escherichia coli components. We estimated kcat/Km for Glu-tRNAGlu, EF-Tu and GTP forming ternary complex (T3) reading cognate (GAA and Gm6AA) or near-cognate (GAU and Gm6AU) codons. ka decreased 10-fold by m6A introduction in cognate and near-cognate cases alike, while Pp for peptidyl transfer remained unaltered in cognate but increased 10-fold in near-cognate case leading to 10-fold amino acid substitution error increase. We estimated kcat/Km for ester bond hydrolysis of P-site bound peptidyl-tRNA by RF2 reading cognate (UAA and Um6AA) and near-cognate (UAG and Um6AG) stop codons to decrease 6-fold or 3-fold by m6A introduction, respectively. This 6-fold effect on UAA reading was also observed in a single-molecule termination assay. Thus, m6A reduces both sense and stop codon reading accuracy by decreasing cognate significantly more than near-cognate kcat/Km, in contrast to most error inducing agents and mutations, which increase near-cognate at unaltered cognate kcat/Km.

scholarly journals Mammalian ALKBH8 Possesses tRNA Methyltransferase Activity Required for the Biogenesis of Multiple Wobble Uridine Modifications Implicated in Translational Decoding

2010 ◽  
Vol 30 (7) ◽  
pp. 1814-1827 ◽  
Author(s):  
Lene Songe-Møller ◽  
Erwin van den Born ◽  
Vibeke Leihne ◽  
Cathrine B. Vågbø ◽  
Terese Kristoffersen ◽  
...  
Keyword(s):  
Stop Codon ◽  
Complete Loss ◽  
Accessory Protein ◽  
Methyltransferase Activity ◽  
Wobble Position ◽  
Trna Methyltransferase ◽  
Codon Reading

ABSTRACT Uridines in the wobble position of tRNA are almost invariably modified. Modifications can increase the efficiency of codon reading, but they also prevent mistranslation by limiting wobbling. In mammals, several tRNAs have 5-methoxycarbonylmethyluridine (mcm5U) or derivatives thereof in the wobble position. Through analysis of tRNA from Alkbh8 −/− mice, we show here that ALKBH8 is a tRNA methyltransferase required for the final step in the biogenesis of mcm5U. We also demonstrate that the interaction of ALKBH8 with a small accessory protein, TRM112, is required to form a functional tRNA methyltransferase. Furthermore, prior ALKBH8-mediated methylation is a prerequisite for the thiolation and 2′-O-ribose methylation that form 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U) and 5-methoxycarbonylmethyl-2′-O-methyluridine (mcm5Um), respectively. Despite the complete loss of all of these uridine modifications, Alkbh8 −/− mice appear normal. However, the selenocysteine-specific tRNA (tRNASec) is aberrantly modified in the Alkbh8 −/− mice, and for the selenoprotein Gpx1, we indeed observed reduced recoding of the UGA stop codon to selenocysteine.

Funktionelle Relevanz der Stop-Codon Mutation rs61757459 in Vaspin (SerpinA12)

2013 ◽  
Vol 8 (S 01) ◽  
Author(s):  
J Breitfeld ◽  
JT Heiker ◽  
Y Böttcher ◽  
D Schleinitz ◽  
A Tönjes ◽  
...  
Keyword(s):  
Stop Codon ◽  
Stop Codon Mutation ◽  
Codon Mutation

Application of Two Neutral Mspl DNA Polymorphisms in the Analysis of Hereditary Protein C Deficiency

1990 ◽  
Vol 64 (02) ◽  
pp. 239-244 ◽  
Author(s):  
P H Reitsma ◽  
W te Lintel Hekkert ◽  
E Koenhen ◽  
P A van der Velden ◽  
C F Allaart ◽  
...  
Keyword(s):  
Protein C ◽  
Stop Codon ◽  
Normal Population ◽  
Amino Acid Position ◽  
Rare Allele ◽  
Dna Polymorphisms ◽  
Type I ◽  
Protein C Deficiency ◽  
Gene Deletions ◽  
Allelic Frequencies

SummaryScreening of restriction erzyme digested DNA from normal and protein C deficient individuals with a variety of probes derived from the protein C locus has revealed the existence of two neutral MspI polymorphism. One polymorphism (MI), which is located ≈7 kb upstream of the protein C gene, has allelic frequencies of 69 and 31%, and was used to exclude extensive gene deletions as a likely cause of type I protein C deficiency in 50% of cases in a panel of 22 families. Furtherrnore, the same polymorphism has been used in 5 doubly affected individuals establishing compound heterozygosity in 3 of these.The second, intragenic, polymorphism (MII) has allelic frequencies of 99 and 1% in the normal population. The frequency of the rare allele of this RFLP was with 7% much higher in a panel of 22 Dutch families with protein C deficiency. Interestingly, in all three probands that were heterozygous for MII the rare allele of MII coincided with a point mutation that leads to a stop codon in amino acid position 306 of the protein C coding sequence. This mutation may account for 14% of the protein C deficient individuals in The Netherlands.

Ectopic Transcript Analysis Indicates that Allelic Exclusion is an Important Cause of Type I Protein C Deficiency in Patients with Nonsense and Frameshift Mutations in the PROC Gene

1996 ◽  
Vol 75 (06) ◽  
pp. 870-876 ◽  
Author(s):  
José Manuel Soria ◽  
Lutz-Peter Berg ◽  
Jordi Fontcuberta ◽  
Vijay V Kakkar ◽  
Xavier Estivill ◽  
...  
Keyword(s):  
Splice Site ◽  
Protein C ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Allelic Exclusion ◽  
Polymorphism Analysis ◽  
Type I ◽  
Protein C Deficiency ◽  
Nonsense Mutations ◽  
Stop Codons

SummaryNonsense mutations, deletions and splice site mutations are a common cause of type I protein C deficiency. Either directly or indirectly by altering the reading frame, these' lesions generate or may generate premature stop codons and could therefore be expected to result in premature termination of translation. In this study, the possibility that such mutations could instead exert their pathological effects at an earlier stage in the expression pathway, through “allelic exclusion” at the RNA level, was investigated. Protein C (PROC) mRNA was analysed in seven Spanish type I protein C deficient patients heterozygous for two nonsense mutations, a 7bp deletion, a 2bp insertion and three splice site mutations. Ectopic RNA transcripts from patient and control lymphocytes were analysed by RT-PCR and direct sequencing of amplified PROC cDNA fragments. The nonsense mutations and the deletion were absent from the cDNAs indicating that only mRNA derived from the normal allele had been expressed. Similarly for the splice site mutations, only normal PROC cDNAs were obtained. In one case, exclusion of the mutated allele could be confirmed by polymorphism analysis. In contrast to these six mutations, the 2 bp insertion was not associated with loss of mRNA from the mutated allele. In this case, cDNA analysis revealed the absence of 19 bases from the PROC mRNA consistent with the generation and utilization of a cryptic splice site 3’ to the site of mutation, which would result in a frameshift and a premature stop codon. It is concluded that allelic exclusion is a common causative mechanism in those cases of type I protein C deficiency which result from mutations that introduce premature stop codons

Alternative Splicing Is Responsible for the Presence of Two Tissue Factor mRNA Species in LPS Stimulated Human Monocytes

1992 ◽  
Vol 67 (02) ◽  
pp. 272-276 ◽  
Author(s):  
C Paul ◽  
E van der Logt ◽  
Pieter H Reitsma ◽  
Rogier M Bertina
Keyword(s):  
Alternative Splicing ◽  
Tissue Factor ◽  
Stop Codon ◽  
Cell Types ◽  
Northern Analysis ◽  
Human Monocytes ◽  
Mrna Species ◽  
Protein Levels ◽  
Intron 1 ◽  
Tf Gene

SummaryAlthough normally absent from the surface of all circulating cell types, tissue factor (TF) can be induced to appear on circulating monocytes by stimulants like bacterial lipopolysaccharide (LPS) and phorbolesters. Northern analysis of RNA isolated from LPS stimulated human monocytes demonstrates the presence of 2.2 kb and 3.1 kb TF mRNA species. The 2.2 kb message codes for the TF protein. As demonstrated by Northern blot analysis with a variety of TF gene probes, the 3.1 kb message arises from an alternative splicing process which fails to remove 955 bp from intron 1. Because of a stop codon in intron 1 no TF protein is produced from the 3.1 kb transcript. This larger transcript should therefore not be taken into account when comparing TF gene transcription and TF protein levels.

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