Structural requirements of the mRNA for intracistronic translation initiation of the enterobacterial <i>infB</i> gene

Laursen, Brian Søgaard; Steffensen, S.; Hedegaard, Jakob; Moreno, Juan Manuel Palacios; Mortensen, Karen Vibeke; Sperling‐Petersen, Hans Uffe

doi:10.1046/j.1365-2443.2002.00571.x

Cited by 21 publications

(20 citation statements)

References 30 publications

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“…The cellular content of IF2-2 and -3 is close to the level of IF2-1 (14,15). The presence of more than one isoform of IF2 is not a phenomenon peculiar to E. coli, but has been found in several other enterobacteria (16).…”

mentioning

confidence: 71%

A Conserved Structural Motif at the N Terminus of Bacterial Translation Initiation Factor IF2

Laursen

Mortensen

Sperling‐Petersen

et al. 2003

Journal of Biological Chemistry

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The 18-kDa Domain I from the N-terminal region of translation initiation factor IF2 from Escherichia coli was expressed, purified, and structurally characterized using multidimensional NMR methods. Residues 2-50 were found to form a compact subdomain containing three short ␤-strands and three ␣-helices, folded to form a ␤␣␣␤␤␣ motif with the three helices packed on the same side of a small twisted ␤-sheet. The hydrophobic amino acids in the core of the subdomain are conserved in a wide range of species, indicating that a similarly structured motif is present at the N terminus of IF2 in many of the bacteria. External to the compact 50-amino acid subdomain, residues 51-97 are less conserved and do not appear to form a regular structure, whereas residues 98 -157 form a helix containing a repetitive sequence of mostly hydrophilic amino acids. Nitrogen-15 relaxation rate measurements provide evidence that the first 50 residues form a well ordered subdomain, whereas other regions of Domain I are significantly more mobile. The compact subdomain at the N terminus of IF2 shows structural homology to the tRNA anticodon stem contact fold domains of the methionyl-tRNA and glutaminyl-tRNA synthetases, and a similar fold is also found in the B5 domain of the phenylalanine-tRNA synthetase. The results of the present work will provide guidance for the design of future experiments directed toward understanding the functional roles of this widely conserved structural domain within IF2.

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mentioning

confidence: 71%

A Conserved Structural Motif at the N Terminus of Bacterial Translation Initiation Factor IF2

Laursen

Mortensen

Sperling‐Petersen

et al. 2003

Journal of Biological Chemistry

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“…Furthermore, we have identified domains I and II of E. coli IF2 as an interaction partner for the infB mRNA (107).…”

Section: Bacillus Subtilis Is the Only Organism That Does Not Belong mentioning

confidence: 96%

“…Three isoforms of the initiation factor, named IF2-1 (97.3 kDa), IF2-2 (79.7 kDa), and IF2-3 (78.8 kDa), exist in E. coli and other members of the family Enterobacteriaceae (107,154).…”

Section: Translation Initiation Factorsmentioning

confidence: 99%

Initiation of Protein Synthesis in Bacteria

Laursen

Sørensen

Mortensen

et al. 2005

Microbiol Mol Biol Rev

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538

506

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Valuable information on translation initiation is available from biochemical data and recently solved structures. We present a detailed description of current knowledge about the structure, function, and interactions of the individual components involved in bacterial translation initiation. The first section describes the ribosomal features relevant to the initiation process. Subsequent sections describe the structure, function, and interactions of the mRNA, the initiator tRNA, and the initiation factors IF1, IF2, and IF3. Finally, we provide an overview of mechanisms of regulation of the translation initiation event. Translation occurs on ribonucleoprotein complexes called ribosomes. The ribosome is composed of a large subunit and a small subunit that hold the activities of peptidyltransfer and decode the triplet code of the mRNA, respectively. Translation initiation is promoted by IF1, IF2, and IF3, which mediate base pairing of the initiator tRNA anticodon to the mRNA initiation codon located in the ribosomal P-site. The mechanism of translation initiation differs for canonical and leaderless mRNAs, since the latter is dependent on the relative level of the initiation factors. Regulation of translation occurs primarily in the initiation phase. Secondary structures at the mRNA ribosomal binding site (RBS) inhibit translation initiation. The accessibility of the RBS is regulated by temperature and binding of small metabolites, proteins, or antisense RNAs. The future challenge is to obtain atomic-resolution structures of complete initiation complexes in order to understand the mechanism of translation initiation in molecular detail

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“…The use of alternative start sites is probably due to leaky ribosome scanning, namely, ribosomes from a 5′ cap bypass the first AUG and start translation from the next AUG. In prokaryotes, intracistronic secondary initiation sites have been reported in only a few cases (38). For example, the E. coli gene coding for a stationary-specific σ-factor produces the σ-factor of 330 amino acids (aa) and the N-terminal truncated σ-factor of 277 aa from the secondary initiation site; both are functional (39).…”

Section: Discussionmentioning

confidence: 99%

Additional pathway to translate the downstream ndhK cistron in partially overlapping ndhC-ndhK mRNAs in chloroplasts

Yukawa

Sugiura

2013

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

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The chloroplast NAD(P)H dehydrogenase ( NDH ) C ( ndhC ) and ndhK genes partially overlap and are cotranscribed in many plants. We previously reported that the tobacco ndhC/K genes are translationally coupled but produce NdhC and NdhK, subunits of the NDH complex, in similar amounts. Generally, translation of the downstream cistron in overlapping mRNAs is very low. Hence, these findings suggested that the ndhK cistron is translated not only from the ndhC 5′UTR but also by an additional pathway. Using an in vitro translation system from tobacco chloroplasts, we report here that free ribosomes enter, with formylmethionyl-tRNA fMet , at an internal AUG start codon that is located in frame in the middle of the upstream ndhC cistron, translate the 3′ half of the ndhC cistron, reach the ndhK start codon, and that, at that point, some ribosomes resume ndhK translation. We detected a peptide corresponding to a 57-amino-acid product encoded by the sequence from the internal AUG to the ndhC stop codon. We propose a model in which the internal initiation site AUG is not designed for synthesizing a functional isoform but for delivering additional ribosomes to the ndhK cistron to produce NdhK in the amount required for the assembly of the NDH complex. This pathway is a unique type of translation to produce protein in the needed amount with the cost of peptide synthesis.

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Structural requirements of the mRNA for intracistronic translation initiation of the enterobacterial infB gene

Cited by 21 publications

References 30 publications

A Conserved Structural Motif at the N Terminus of Bacterial Translation Initiation Factor IF2

A Conserved Structural Motif at the N Terminus of Bacterial Translation Initiation Factor IF2

Initiation of Protein Synthesis in Bacteria

Additional pathway to translate the downstream ndhK cistron in partially overlapping ndhC-ndhK mRNAs in chloroplasts

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