Proteolysis of <i>Bacillus stearothermophilus</i> IF2 and specific protection by fMet‐tRNA

Severini, M.; Choli, Theodora; Teana, Anna La; Gualerzi, Claudio O.

doi:10.1016/0014-5793(92)80543-p

Cited by 9 publications

(7 citation statements)

References 13 publications

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“…Furthermore, residues within the GII peptide Asn 611-Arg 645 of E. coli IF2 (corresponding to Asn 464-Glu 498 of B. stearothermophilus) were found to be close to the elbow region of the tRNA (Wakao et al 1989;Yusupova et al 1996). Finally, binding of fMet-tRNA to B. stearothermophilus IF2 was found to protect the Arg 308-Ala 309 bond, located in the GTP-binding domain GI, and, more weakly, the Arg 519-Ser 520 bond in the GII domain from trypsin digestion (Severini et al 1992).…”

Section: Discussionmentioning

confidence: 99%

Ribosomal localization of translation initiation factor IF2

Marzi¹,

Knight²,

Brandi³

et al. 2003

RNA

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Bacterial translation initiation factor IF2 is a GTP-binding protein that catalyzes binding of initiator fMet-tRNA in the ribosomal P site. The topographical localization of IF2 on the ribosomal subunits, a prerequisite for understanding the mechanism of initiation complex formation, has remained elusive. Here, we present a model for the positioning of IF2 in the 70S initiation complex as determined by cleavage of rRNA by the chemical nucleases Cu(II):1,10-orthophenanthroline and Fe(II):EDTA tethered to cysteine residues introduced into IF2. Two specific amino acids in the GII domain of IF2 are in proximity to helices H3, H4, H17, and H18 of 16S rRNA. Furthermore, the junction of the C-1 and C-2 domains is in proximity to H89 and the thiostrepton region of 23S rRNA. The docking is further constrained by the requisite proximity of the C-2 domain with P-site-bound tRNA and by the conserved GI domain of the IF2 with the large subunit's factor-binding center. Comparison of our present findings with previous data further suggests that the IF2 orientation on the 30S subunit changes during the transition from the 30S to 70S initiation complex.

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Section: Discussionmentioning

confidence: 99%

Ribosomal localization of translation initiation factor IF2

Marzi¹,

Knight²,

Brandi³

et al. 2003

RNA

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“…A six domain structural model has been proposed for this multi‐functional factor [2]in which domain I constitutes the difference between IF2α and IF2β. The GTP‐binding domain is located within domain IV and the C‐terminal domain VI has been shown to be involved in the tRNA binding [3]. Domain V probably supports the functions of domains IV and VI.…”

Section: Introductionmentioning

confidence: 90%

E. coli translation initiation factor IF2 – an extremely conserved protein. Comparative sequence analysis of the infB gene in clinical isolates of E. coli

et al. 1997

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The functionally uncharacterised N-terminal of translation initiation factor IF2 has been found to be extremely variable when comparing different bacterial species. In order to study the intraspecies variability of IF2 the 2670 basepairs nucleotide sequence of the infB gene (encoding IF2) was determined in 10 clinical isolates of E. coli. The N-terminal domains (I, II and III) were completely conserved indicating a specific function of this region of IF2. Only one polymorphic position was found in the deduced 890 amino acid sequence. This Gln/Gly490 is located within the central GTP/GDP-binding domain IV of IF2. The results are further evidence that IF2 from E. coli has reached a highly defined level of structural and functional development.

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“…Cross-linking experiments indicate interactions between E. coli residues N611-R645 (belonging to domain V) and the T-stem of fMet-tRNA f Met as well as residues W215-R237 (domain II) and the anticodon stem of fMettRNA f Met (243,257). Finally, fMet-tRNA f Met protects a position in domain IV and weakly in domain V of B. stearothermophilus IF2 against digestion by trypsin (205). A stable interaction between the archaeal and eukaryotic IF2 homologues and Met-tRNA i Met has not been observed in vitro, but overexpression of the gene encoding tRNA i…”

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

confidence: 99%

Initiation of Protein Synthesis in Bacteria

Laursen

Sørensen

Mortensen

et al. 2005

Microbiol Mol Biol Rev

540

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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Proteolysis of Bacillus stearothermophilus IF2 and specific protection by fMet‐tRNA

Cited by 9 publications

References 13 publications

Ribosomal localization of translation initiation factor IF2

Ribosomal localization of translation initiation factor IF2

E. coli translation initiation factor IF2 – an extremely conserved protein. Comparative sequence analysis of the infB gene in clinical isolates of E. coli

Initiation of Protein Synthesis in Bacteria

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