Specific functional interactions of nucleotides at key -3 and +4 positions flanking the initiation codon with components of the mammalian 48S translation initiation complex.

By A. Pisarev, V. Kolupaeva, V. Pisareva, W. Merrick, C. Hellen, T. Pestova. 2006

231 citations recorded by the source corpus.

Eukaryotic initiation factor (eIF) 1 maintains the fidelity of initiation codon selection and enables mammalian 43S preinitiation complexes to discriminate against AUG codons with a context that deviates from the optimum sequence GCC(A/G)CCAUGG, in which the purines at (-)3 and (+)4 positions are most important. We hypothesize that eIF1 acts by antagonizing conformational changes that occur in ribosomal complexes upon codon-anticodon base-pairing during 48S initiation complex formation, and that the role of (-)3 and (+)4 context nucleotides is to stabilize these changes by interacting with components of this complex. Here we report that U and G at (+)4 both UV-cross-linked to ribosomal protein (rp) S15 in 48S complexes. However, whereas U cross-linked strongly to C(1696) and less well to AA(1818-1819) in helix 44 of 18S rRNA, G cross-linked exclusively to AA(1818-1819). U at (-)3 cross-linked to rpS5 and eIF2alpha, whereas G cross-linked only to eIF2alpha. Results of UV cross-linking experiments and of assays of 48S complex formation done using alpha-subunit-deficient eIF2 indicate that eIF2alpha's interaction with the (-)3 purine is responsible for recognition of the (-)3 context position by 43S complexes and suggest that the (+)4 purine/AA(1818-1819) interaction might be responsible for recognizing the (+)4 position.

Subfields: Molecular Biology

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Citations in the corpus

Protein Synthesis Initiation in Eukaryotic Cells. (2018, background): “Likewise eIF2α contacts the conserved mRNA nucleotide at the –3 position using Arg54, which is close to the regulatorySer51 residue, in agreementwithprior cross-linking experiments (Pisarev et al. 2006).”
Structural Insights into the Mechanism of Scanning and Start Codon Recognition in Eukaryotic Translation Initiation. (2017, unknown): “This interaction agrees with crosslinking of eIF2a to the 3 nucleotide in reconstituted mammalian PICs and biochemical data indicating that meIF2a stabilizes 48S PICs and mediates the stimulatory effect of a 3 purine on 48S assembly [27].”
Structural Changes Enable Start Codon Recognition by the Eukaryotic Translation Initiation Complex (2014, background): “…and Arg57 in a conserved loop of eIF2a-D1 and the 3 and 2 positions of mRNA, respectively (Figure 6A), which is consistent with biochemical evidence that interaction of eIF2a with the 3 nucleotidemediates the stimulatory effect of a purine at that position on AUG recognition (Pisarev et al., 2006).”
The eukaryotic translation initiation factors eIF1 and eIF1A induce an open conformation of the 40S ribosome. (2007, background): “It has been suggested that eIF1 antagonizes the closed, scanning-incompetent structure of the initiation complex that forms upon recognition of the start codon (Pisarev et al., 2006).”
THE MECHANISM OF EUKARYOTIC TRANSLATION INITIATION AND PRINCIPLES OF ITS REGULATION (2010, background): “It enables 43S complexes to discriminate against non-AUG triplets and AUG triplets that have poor context or are located within 8 nucleotides of the mRNA 5′ end, and also dissociates the ribosomal complexes that aberrantly assemble at such triplets in its absenc”
eIF5 and eIF5B together stimulate 48S initiation complex formation during ribosomal scanning (2014, background): “It has been shown that eIF5 and eIF5B together after the establishment of codon–anticodon interaction almost completely dissociate eIF2 from the 40S subunit (32), whereas eIF3, due to additional contacts with mRNA, dissociates only after 80S IC formation (24).”
Structural Insights into the Mammalian Late-Stage Initiation Complexes (2020, background): “In addition, cross-linking studies of reconstitutedmammalian PIC previously demonstrated that eIF2a and uS7 interact with the ( 3) nucleotide and uS7with the ( 4) nucleotide (Pisarev et al., 2006, 2008).”
The scanning mechanism of eukaryotic translation initiation. (2014, background): “F or p er so na l u se o nl y. translation in mammalian extracts (200), and destabilized mammalian PICs following GTP hydrolysis in the TC (201).”
eIF3j is located in the decoding center of the human 40S ribosomal subunit. (2007, background): “The only other eukaryotic initiation factor suggested to be similarly positioned is the a subunit of eIF2, which was found to crosslink to the À3 position of an mRNA (Pisarev et al., 2006).”