Translational Control of Gene Expression in E. Coli and Bacteriophage

Springer, Mathias

doi:10.1007/978-1-4684-8601-8_6

Cited by 12 publications

(13 citation statements)

References 174 publications

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“…Because no promoters for recJ were found in this region (36), we believe it is more likely that the increase represents improved translation of recJ in the presence of translation of the upstream dsbC gene. The spacing of the two reading frames may be close enough to allow translational reinitiation (50). If the defect in the recJ153 mutants lies in inefficient translation initiation, then elevation of mRNA levels artificially should relieve the mutant phenotype.…”

Section: Resultsmentioning

confidence: 99%

IF3-mediated suppression of a GUA initiation codon mutation in the recJ gene of Escherichia coli

Haggerty

Lovett

1997

J Bacteriol

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A mutational change of the initiation codon to GUA was found to reduce, but not abolish, expression of the recJ gene of Escherichia coli. Specific mutations in translational initiation factor IF3 have been isolated as second-site suppressors of this GUA initiation codon mutation. One of these, infC135, with an arginine-toproline change at amino acid 131, completely restores a wild-type phenotype to recJ GUA initiation codon mutants and acts in a semidominant fashion. The infC135 mutation increased expression of RecJ from the GUA mutant but had no effect on the normal GUG start. The infC135 mutation also abolished autoregulation of IF3 in cis and in trans. The behavior of this IF3 mutant suggests that it has specifically lost its ability to abort initiation from poor initiation codons such as GUA of recJ and the AUU of infC. Because of the impact of IF3 on recJ, a recombination and repair gene, this role of IF3 must be general and not restricted to translation genes. The dominance of infC135 suggests that the other functions of IF3, for instance its ability to bind to 30S ribosomes, must remain intact. Although the ability to discriminate among initiation codons has been lost in the infC135 mutant, translational initiation was still restricted to the normal initiation site in recJ, even in the presence of a closely juxtaposed alternative initiation codon. Because the recJ gene lacks a canonical ShineDalgarno sequence, other unknown features of the mRNA must serve to specify the initiation site.Prokaryotic translation initiation requires several protein factors (23,24,27). The translation initiation factor IF3 is believed to be essential for selection of the initiation codon by monitoring the pairing between the initiator fMet-tRNA and the initiation codon (26,28). If this pairing is good, as in an AUG start codon, IF3 stabilizes the translation initiation complex and translation initiation proceeds. If the codon is suboptimal, IF3 destabilizes this complex and translation initiation is disfavored (4,22,43). This function is dependent on the ratio of IF3 to ribosomes in vivo (31). If the ratio is high, IF3 promotes discrimination between initiation codons. If the ratio falls so that IF3 is limiting, translational initiation from non-AUG codons will be increased. This phenomenon allows IF3 to autoregulate its own translation through use of its unique AUU initiation codon (7-9). IF3 therefore controls translation fidelity by preventing inappropriate initiation.IF3 serves several other functions in translation initiation. IF3 favors the dissociated state of ribosomes by binding to the 30S subunit and preventing association with the 50S subunit until a stable translation initiation complex is formed (20, 51). IF3 may also recruit IF1 and IF2 to the 30S subunit and destabilize the binding of noninitiator tRNAs (23).We have previously shown that certain mutations in IF3 could genetically suppress two particular alleles of the recJ gene of Escherichia coli (25). One such suppressor was initially designated as srjA5, for ...

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Section: Resultsmentioning

confidence: 99%

IF3-mediated suppression of a GUA initiation codon mutation in the recJ gene of Escherichia coli

Haggerty

Lovett

1997

J Bacteriol

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“…Such secondary structure can exert a regulatory role in translation by a variety of mechanisms (de Smit and van Duin 1990b;Springer 1996). In the case of rpoH, the initiation codon and region A are masked by region B located far downstream, forming a complex structure that consists of several stem-loops (Fig.…”

Section: Discussionmentioning

confidence: 99%

Translational induction of heat shock transcription factor sigma 32: evidence for a built-in RNA thermosensor

Morita¹,

Tanaka²,

Kodama³

et al. 1999

Genes & Development

274

260

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Induction of heat shock proteins in Escherichia coli is primarily caused by increased cellular levels of the heat shock -factor 32 encoded by the rpoH gene. Increased 32 levels result from both enhanced synthesis and stabilization. Previous work indicated that 32 synthesis is induced at the translational level and is mediated by the mRNA secondary structure formed within the 5-coding sequence of rpoH, including the translation initiation region. To understand the mechanism of heat induction of 32 synthesis further, we analyzed expression of rpoH-lacZ gene fusions with altered stability of mRNA structure before and after heat shock. A clear correlation was found between the stability and expression or the extent of heat induction. Temperature-melting profiles of mRNAs with or without mutations correlated well with the expression patterns of fusion genes carrying the corresponding mutations in vivo. Furthermore, temperature dependence of mRNA-30S ribosome-tRNA f Met complex formation with wild-type or mutant mRNAs in vitro agreed well with that of the expression of gene fusions in vivo. Our results support a novel mechanism in which partial melting of mRNA secondary structure at high temperature enhances ribosome entry and translational initiation without involvement of other cellular components, that is, intrinsic mRNA stability controls synthesis of a transcriptional regulator.

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“…Such mRNA may have only one RBS; the start of the coding for protein A 2 can be close enough to the end of the coding for protein A 1 that a ribosome can immediately "read-through" to the A 2 coding region after releasing an A 1 . 11 A model for such a scheme is shown in Figure 1(c). By solving for the moments of a master equation, 12 the intrinsic noise can be shown to be:…”

Section: Polycistronic Mrnasmentioning

confidence: 99%

Efficient Attenuation of Stochasticity in Gene Expression Through Post-transcriptional Control

Swain

2004

Journal of Molecular Biology

206

221

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Translational Control of Gene Expression in E. Coli and Bacteriophage

Cited by 12 publications

References 174 publications

IF3-mediated suppression of a GUA initiation codon mutation in the recJ gene of Escherichia coli

IF3-mediated suppression of a GUA initiation codon mutation in the recJ gene of Escherichia coli

Translational induction of heat shock transcription factor sigma 32: evidence for a built-in RNA thermosensor

Efficient Attenuation of Stochasticity in Gene Expression Through Post-transcriptional Control

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