Amino acid sequence analysis of the β- and γ-subunits of eukaryotic initiation factor eIF-2. Identification of regions interacting with GTP

Bommer, Ulrich‐Axel; Kraft, Regine; Kurzchalia, Teymuras V.; Price, Nigel T.; Proud, Christopher G.

doi:10.1016/0167-4838(91)90074-a

Cited by 25 publications

(16 citation statements)

References 15 publications

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“…1). The subsequent loop region is then located near the ribose moiety of the bound GDP with a minimum distance of Ϸ7 Å, which is consistent with the affinity labeling of this region with the ribose moiety of the GTP analog (14), albeit without direct interaction. The ␤-subunit interacts only with the G domain and is distant from domains 2 and 3, to which the ␣-subunit and Met-tRNA i bind (5).…”

Section: Resultsmentioning

confidence: 48%

Structure of archaeal translational initiation factor 2 βγ–GDP reveals significant conformational change of the β-subunit and switch 1 region

Sokabe

Yao

Sakai

et al. 2006

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

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Archaeal͞eukaryotic initiation factor 2 (a͞eIF2) consists of ␣-, ␤-, and ␥-subunits and delivers initiator methionine tRNA (Met-tRNAi) to a small ribosomal subunit in a GTP-dependent manner. The structures of the aIF2␤␥ (archaeal initiation factor 2 ␤␥) heterodimeric complex in the apo and GDP forms were analyzed at 2.8-and 3.4-Å resolution, respectively. The results showed that the N-terminal helix and the central helix-turn-helix domain of the ␤-subunit bind to the G domain of the ␥-subunit but are distant from domains 2 and 3, to which the ␣-subunit and Met-tRNAi bind. This result is consistent with most of the previous analyses of eukaryotic factors, and thus indicates that the binding mode is essentially conserved among a͞eIF2. Comparison with the uncomplexed structure showed significant differences between the two forms of the ␤-subunit, particularly the C-terminal zinc-binding domain, which does not interact with the ␥-subunit and was suggested previously to be involved in GTP hydrolysis. Furthermore, the switch 1 region in the ␥-subunit, which is shown to be responsible for Met-tRNA i binding by mutational analysis, is moved away from the nucleotide through the interaction with highly conserved R87 in the ␤-subunit. These results implicate that conformational change of the ␤-subunit facilitates GTP hydrolysis by inducing the conformational change of the switch 1 region toward the off state.initiator methionine tRNA ͉ ribosome

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Section: Resultsmentioning

confidence: 48%

Structure of archaeal translational initiation factor 2 βγ–GDP reveals significant conformational change of the β-subunit and switch 1 region

Sokabe

Yao

Sakai

et al. 2006

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

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“…Comparison of published amino acid sequence data for eIF-2,y peptides with the deduced GCD11 sequence revealed blocks of sequences similar to the y 1, 2a, 2b, 3b, 4a, and 6 peptides determined by Suzuki et al (67).for porcine eIF-2y and the fragment 1 and 2 peptides determined by Bommer et al (6) for rabbit eIF-21y. These peptides are aligned with the deduced GCD11 amino acid sequence in Fig.…”

Section: Resultsmentioning

confidence: 97%

“…Alignment of the rabbit and porcine eIF-2-y peptides (lower sequences) with the predicted GCD11 amino acid sequence (upper sequence). Underlined peptides were determined by Suzuki et al (67) for porcine eIF-2y; shaded peptides were determined by Bommer et al (6) for rabbit eIF-2y; boxed peptides are those reported in this paper (see also Table 2). Single-letter amino acid codes are used, with X indicating uncertainty in determining the amino acid at that position.…”

Section: Resultsmentioning

confidence: 99%

“…Previous experiments in which guanine nucleotide analogs were cross-linked to rabbit eIF-2 indicated that GTP-binding might be a shared function of the j and y subunits (3,6 [and references cited therein]). The presence of two putative GTP-binding elements (DXXG and NKXD) within the predicted human eIF-2p polypeptide (54) is consistent with the notion of shared binding.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

GCD11, a negative regulator of GCN4 expression, encodes the gamma subunit of eIF-2 in Saccharomyces cerevisiae.

Hannig¹,

Cigan²,

Freeman³

et al. 1993

Mol. Cell. Biol.

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The eukaryotic translation initiation factor eIF-2 plays a critical role in regulating the expression of the yeast transcriptional activator GCN4. Mutations in genes encoding the a and 1 subunits of eIF-2 alter translational efficiency at the GCN4 AUG codon and constitutively elevate GCN4 translation. Mutations in the yeast GCDII gene have been shown to confer a similar phenotype. The nucleotide sequence of the cloned GCDII gene predicts a 527-amino-acid polypeptide that is similar to the prokaryotic translation elongation factor EF-Tu. Relative to EF-Tu, the deduced GCD11 amino acid sequence contains a 90-amino-acid N-terminal extension and an internal cysteine-rich sequence that contains a potential metal-binding finger motif. We have identified the GCDII gene product as the 'y subunit of eIF-2 by the following criteria: (i) sequence identities with mammalian eIF-2'y peptides; (ii) increased eIF-2 activity in extracts prepared from cells cooverexpressing GCD11, eIF-2a, and eIF-21; and (iii) cross-reactivity of antibodies directed against the GCD11 protein with the 58-kDa polypeptide present in purified yeast eIF-2. The predicted GCD11 polypeptide contains all of the consensus elements known to be required for guanine nucleotide binding, suggesting that, in Saccharomyces cerevisiae, the 'y subunit of eIF-2 is responsible for GDP-GTP binding. tRNA, recognizes an mRNA (which is bound by an additional set of initiation factors) and attaches at or near its 5' capped end. The factor-bound 40S subunit then scans the mRNA linearly in a 5'-to-3' direction until it encounters an AUG translation initiation codon in a favorable context (41). Upon reaching the start codon, GTP is hydrolyzed, Met-tRNA, is donated to the ribosomal half-P site, and eIF-lA, eIF-3, and eIF-2-GDP are released from the 40S subunit in a reaction promoted by eIF-S. The eIF-2-GDP complex formed as a result of GTP hydrolysis must be converted to the GTP-bound form to allow eIF-2 to bind Met-tRNA, and participate in a subsequent round of initiation. The reaction in which GTP is exchanged for the GDP bound to eIF-2 is catalyzed by the guanine nucleotide exchange factor eIF-2B.In both amino acid-starved and unstarved cells, it appears that ribosomes initiate protein synthesis at the AUG codon of the 5'-proximal uORF (uORF1) on GCN4 mRNA, terminate three codons downstream at an in-frame termination codon, and dissociate from the mRNA. There is evidence, however, that about one-half of the 40S subunits that terminate at uORF1 remain associated with the GCN4 mRNA and resume scanning (1). (1,49). Amino acid starvation results in reduced reinitiation at uORFs 2, 3, and 4 and increased reinitiation at the GCN4 AUG codon, perhaps because of a decrease in the activity of one or more initiation factors (1).Genetic and molecular analyses have identified the initiation factor eIF-2 as a key regulator of GCN4 expression. In S. cerevisiae, as well as in mammals, eIF-2 is composed of three nonidentical subunits termed a

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“…These results suggest that the sequence of peptide y 7660 was involved in the binding of GTP to eIF-2. Bommer et al 21 ) sequenced several CNBr fragments of rabbit reticulocyte eIF-2y and found a sequence, AVKADLGK, similar to the consensus sequence element GXXXXGK (see Table I). They pointed out that the sequence differs in several respects from the consensus sequence.…”

Section: B) Materials (2 X 10mentioning

confidence: 99%

GTP-Binding Sequences in theγSubunit of Pig Liver Initiation Factor 2

Mukouyama¹,

Shiokawa²,

Suzuki³

1992

Bioscience, Biotechnology, and Biochemistry

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Amino acid sequence analysis of the β- and γ-subunits of eukaryotic initiation factor eIF-2. Identification of regions interacting with GTP

Cited by 25 publications

References 15 publications

Structure of archaeal translational initiation factor 2 βγ–GDP reveals significant conformational change of the β-subunit and switch 1 region

Structure of archaeal translational initiation factor 2 βγ–GDP reveals significant conformational change of the β-subunit and switch 1 region

GCD11, a negative regulator of GCN4 expression, encodes the gamma subunit of eIF-2 in Saccharomyces cerevisiae.

GTP-Binding Sequences in theγSubunit of Pig Liver Initiation Factor 2

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