The mechanism of action of initiaton factor 3 in protein synthesis, I. Studies on ribosomes crosslinked with dimethylsuberimidate

Hawley, David; Miller, Martha J.; Slobin, Lawrence I.; Wahba, Amy

doi:10.1016/0006-291x(74)90570-1

Cited by 20 publications

(12 citation statements)

References 17 publications

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“…Slot 4 also shows that some of the labeled A site fragment becomes degraded during incubation at 38'. However, slot 7 and experiments described below indicate that the intact initiator region, rather than small degradation products, is bound to the colicin fragment.…”

mentioning

confidence: 99%

“…First, crosslinking (6)(7)(8) and other chemical (9) data suggest that the 3' end of 16S RNA, the binding sites for initiation factors, and certain ribosomal proteins implicated in initiation (10)(11)(12)(13) may all be neighbors in the 30S ribosome. Second, studies of several antibiotic inhibitors of initiation (14,15) indicate that their sites of action likewise lie in the vicinity of the 3' end of 16S RNA.…”

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confidence: 99%

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How ribosomes select initiator regions in mRNA: base pair formation between the 3' terminus of 16S rRNA and the mRNA during initiation of protein synthesis in Escherichia coli.

Steitz¹,

Jakes²

1975

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

643

225

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Initiation complexes formed by E. coli ribosomes in the presence of 32P-labeled A protein initiator region from R17 bacteriophage RNA have been treated with colicin E3 and disassembled by exposure to 1% sodium dodecyl sulfate. Electrophoresis on 9% polyacrylamide gels reveals a dissociabte complex containing the 30-nucleotide-long messenger fragment and the 50-nucleotide-long colicin fragment, which arises from the 3' terminus of the 16S RNA. The complex is a pure RNA-RNA hybrid; it is apparently maintained by a seven-base complementarity between the two RNA fragments.Detection of this mRNA rRNA complex strongly supports the hypothesis that during the initiation step of protein biosynthesis the 3' end of 16S RNA base pairs with the polypurine stretch common to initiator regions in E. coli and bacteriophage mRNAs. The implications of our findings with respect to the molecular mechanism of initiation site selection and mRNA binding to ribosomes, the role of rRNA in ribosome function, and species specificity in translation are explored.Shine and Dalgarno (1) originally suggested that a sequence near the 3' terminus of Escherschla coli 16S ribosomal RNA participates directly in the initiation of protein biosynthesis by forming several Watson-Crick base pairs with the messenger RNA. Indeed, one of the few common features of all ribosome-protected initiator regions analyzed so far is a polypurine stretch of 3 to 8 nucleotides located about 10 bases 5' to the initiator codon (Table 1). From 3 to 7 contiguous bases within this region of each mRNA can potentially pair with some portion of the polypyrimidine sequence found in the 3'-terminal Ti oligonucleotide of 16S RNA. Although the relevant 16S RNA sequence as determined by Shine and Dalgarno (1) conflicted with previous reports (2), its validity has now been confirmed in three additional laboratories (3-5).

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confidence: 99%

mentioning

confidence: 99%

How ribosomes select initiator regions in mRNA: base pair formation between the 3' terminus of 16S rRNA and the mRNA during initiation of protein synthesis in Escherichia coli.

Steitz¹,

Jakes²

1975

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

643

225

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“…Here it should be noted that using bifunctional electrophilic reagents, IF-3 has been shown to cross-link to S7 [14], and to Sl, Sll, S12, S13, S19, and S21 [15,16]. At the present time we cannot exclude the possibility that the observed cross-links, especially peak I, arise from simultaneous cross-linking of IF-3 to two ribosomal proteins.…”

Section: Incorporation Into Proteinmentioning

confidence: 67%

Photosensitized cross‐linking of IF‐3 to Escherichia coli 30 S subunits

et al. 1977

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“…RRF binding site on the ribosome is near A/P site [26][27][28], while the binding site of IF3 is near the P and E sites of the ribosome [29,30] hence IF3 binding site does not overlap the RRF and EF-G binding sites. And two reports have shown that IF3 can bind to 70S and loosen its structure without splitting it into its subunits [31,32]. Thus, we suspect that the substrate for the stable dissociation is the 70S-IF3 complex.…”

Section: Discussionmentioning

confidence: 89%

Spermidine inhibits transient and stable ribosome subunit dissociation

Umekage

Ueda

2006

FEBS Letters

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Recent light-scattering experiments and sucrose density gradient centrifugational analyses suggested that the 70S ribosome undergoes RRF-and EF-G-triggered transient subunit dissociation that is followed by IF3-induced stable dissociation. However, the experimental conditions did not include the ubiquitous cellular polyamine spermidine, which is required for efficient translation. We found that when spermidine was present, the transient dissociation was inhibited. Moreover, the published experiments used ribosome concentrations that were far lower than the physiological concentration. We found that when spermidine and higher ribosome concentrations were included in the experimental conditions, only very limited stable subunit dissociation was observed. These results suggest that neither transient nor stable dissociation occurs under physiological conditions applied here.

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The mechanism of action of initiaton factor 3 in protein synthesis, I. Studies on ribosomes crosslinked with dimethylsuberimidate

Cited by 20 publications

References 17 publications

How ribosomes select initiator regions in mRNA: base pair formation between the 3' terminus of 16S rRNA and the mRNA during initiation of protein synthesis in Escherichia coli.

How ribosomes select initiator regions in mRNA: base pair formation between the 3' terminus of 16S rRNA and the mRNA during initiation of protein synthesis in Escherichia coli.

Photosensitized cross‐linking of IF‐3 to Escherichia coli 30 S subunits

Spermidine inhibits transient and stable ribosome subunit dissociation

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