Mistranslation in cells infected with the bacteriophage MS2: Direct evidence of Lys for Asn substitution

Parker, Jack; Johnston, Timothy C.; Borgia, Peter T.

doi:10.1007/bf00425839

Cited by 53 publications

(24 citation statements)

References 28 publications

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“…As early as the advent of two-dimensional gel electrophoresis in the 1970s, it was observed that under nutritional or environmental stress, cells often produce proteins that seem to deviate from those programmed by the genetic code (54). Starving E. coli for the amino acid asparagines (Asn) leads to readily detectable levels of proteins that contain non-Asn substitutions such as lysine (Lys, (56)). This result was interpreted as Asn starvation decreasing the amount of charged tRNA Asn (which reads AAC/AAU codons) so that the near-cognate tRNA Lys (which reads AAG/AAA codons) can read the Asn codons to make Asn-to-Lys mutant proteins.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Translation as a Mechanism of Stress Response and Adaptation

Pan

2013

Annu. Rev. Genet.

107

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The composition of the cellular proteome is commonly thought to strictly adhere to the genetic code. However, accumulating evidence indicates that cells also regulate the synthesis of mutant protein molecules that deviate from the genetic code. Production of mutant proteins varies in amounts and specificity and generally occurs when cells are stressed or undergo environmental adaptation. The deliberate synthesis of protein mutants suggests that some of these proteins can be useful in cellular stress response and adaptation. This review describes the occurrence, the translation mechanisms, and the functional hypotheses on regulated synthesis of mutant proteins.

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Section: Introductionmentioning

confidence: 99%

Adaptive Translation as a Mechanism of Stress Response and Adaptation

Pan

2013

Annu. Rev. Genet.

107

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“…This should lead to a proportionate reduction in the concentration of the corresponding ternary complex, elongation factor Tu (EF-Tu)-GTP-aminoacyl-tRNA, and hence in its ability to compete with near-cognate ternary complexes for reaction with the ribosome (2). However, in E. coli the accuracy of aminoacyl-tRNA incorporation into proteins seems unaffected (6,7), or only moderately affected (8), by amino acid starvation. RelA mutants of E. coli have lost this ability to preserve translational fidelity during starvation; when these strains are starved for an amino acid, the error rate for translation of codons calling for that amino acid increases dramatically (6,7).…”

mentioning

confidence: 96%

Elongation factor Tu.guanosine 3'-diphosphate 5'-diphosphate complex increases the fidelity of proofreading in protein biosynthesis: mechanism for reducing translational errors introduced by amino acid starvation.

Dix¹,

Thompson²

1986

Proc. Natl. Acad. Sci. U.S.A.

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Complexes of elongation factor Tu (EF-Tu) with guanosine 3'-diphosphate 5'-diphosphate (ppGpp) bind to ribosomes where they slow the incorporation of aminoacyltRNAs into protein by inhibiting both the binding of aminoacyltRNA-EF-Tu-GTP ternary complexes and the formation of peptide bonds. The latter action increases the time available for aminoacyl-tRNA rejection by the ribosome and, therefore, increases the effectiveness of proofreading. Synthesis of ppGpp and the formation of EF-Tu ppGpp occur in vivo in response to amino acid starvation. Our finding, therefore, suggests an explanation for the otherwise puzzling observation that amino acid starvation has, at most, a moderate effect on the fidelity of protein synthesis in wild-type Escherichia coli. We suggest that an EF-Tu-ppGpp-induced increase in the effectiveness of proofreading buffers the overall translational fidelity of these cells against amino acid starvation-induced errors in initial selection of aminoacyl-tRNA ternary complexes.The fidelity of processes that allow a gene to direct the synthesis of a protein is of vital importance to the cell. Where these processes have been studied in detail, they have been found to have complex error correction mechanisms. Nonetheless, their overall fidelity should obey certain simple rules. For example, when two substrates, one cognate and the other near-cognate, compete for the active site of an enzyme, the error rate (E) will be equal to the relative rates of the cognate (Vc) and the near-cognate (Vn) reactions, and this ratio should be determined by the product of the relative rate constants for the cognate (Ic) and near-cognate (kn) reactions and the relative concentrations of the cognate ([C]) and near-cognate ([N]) substrates (1,2).

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“…After a temperature shift to 40°C, peptidyl-tRNA accumulation begins, and less and less tRNA remains available for continued protein synthesis. There is ample evidence that depletion of a tRNA species leads to increased misreading of its corresponding codon(s) (6,8,9,(18)(19)(20). Misreading could keep protein synthesis going for a while at the expense of increased error rates.…”

Section: Discussionmentioning

confidence: 99%

Effect of a 2-methylthio-N6-isopentenyladenosine deficiency on peptidyl-tRNA release in Escherichia coli

Petrullo¹,

Elseviers²

1986

J Bacteriol

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We examined the effect of miaA, a mutation conferring a deficiency in 2-methylthio-N6-isopentenyladenosine in tRNA, on patterns of peptidyl-tRNA accumulation in Escherichia coli strains deficient in peptidyl-tRNA hydrolase activity. A specific reduction in peptidyl-tRNA accumulation was seen for tRNAs which normally contain the 2-methylthio-N6-isopentenyladenosine modification. These results provide new evidence in support of the ribosome editor model, which links peptidyl-tRNA release to mistranslation events.The isolation of a temperature-sensitive mutation in an Escherichia coli gene coding for peptidyl-tRNA hydrolase (pth) was reported by Atherly and Menninger in 1972 (1). This enzyme specifically cleaves peptides from cytoplasmic peptidyl-tRNA. The pth mutation is conditionally lethal (16). This implies that peptidyl-tRNA hydrolase is an essential enzyme in E. coli. Yet, in the classical description of protein synthesis, there is no step where cytoplasmic peptidyl-tRNA is generated. In addition, the release of a nonfunctional, half-finished peptide from the ribosome seems extremely wasteful.These considerations led Menninger (11) to propose that the release of peptidyl-tRNA is associated with a proofreading mechanism, the so-called ribosome editor. In this model, the premature release of peptidyl-tRNA is the result of an active editing mechanism which recognizes and specifically releases noncognate tRNA molecules that have escaped proofreading in the acceptor (A) site (23). Recent evidence suggests that peptidyl-tRNA release is associated with the translocation step (15).The ribosome editor hypothesis leads to a very precise prediction. The vast majority of, if not all, tRNA molecules released as peptidyl-tRNA should be noncognate; i.e., they should have been released in the process of mistranslating a codon. However, testing this precise prediction directly has proven difficult (2, 3).Here we describe a new approach to test the ribosome editor hypothesis. We previously studied the effect of miaA, a mutation which causes a deficiency in 2-methylthio-N6-isopentenyladenosine in tRNA, on the readthrough and suppression of nonsense mutations in E. coli (21). This modification in 2-methylthio-N6-isopentenyladenosine, hereafter called isopentenyladenosine, occurs 3' adjacent to the anticodon in all tRNAs that read codons beginning with uracil (17). Those rely ,more heavily on tRNA modifications such as the isopentenyladenosine modification for stabilization in the A site of a programmed ribosome.The miaA mutation can be used to tag genetically a subpopulation of tRNAs. Based on our previous results, introduction of the miaA allele should specifically reduce the ability of miaA tRNAs to misread other codons but leave all other aspects of protein synthesis more or less unaltered. Here we report how the miaA mutation influenced patterns of peptidyl-tRNA release. Our approach had the advantage that the ribosome and therefore the ribosome editor remained unaltered throughout these experiments. modification was also ...

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Mistranslation in cells infected with the bacteriophage MS2: Direct evidence of Lys for Asn substitution

Cited by 53 publications

References 28 publications

Adaptive Translation as a Mechanism of Stress Response and Adaptation

Adaptive Translation as a Mechanism of Stress Response and Adaptation

Elongation factor Tu.guanosine 3'-diphosphate 5'-diphosphate complex increases the fidelity of proofreading in protein biosynthesis: mechanism for reducing translational errors introduced by amino acid starvation.

Effect of a 2-methylthio-N6-isopentenyladenosine deficiency on peptidyl-tRNA release in Escherichia coli

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