GTP-dependent Recognition of the Methionine Moiety on Initiator tRNA by Translation Factor eIF2

Kapp, Lee D.; Lorsch, Jon R.

doi:10.1016/j.jmb.2003.11.025

Cited by 135 publications

(185 citation statements)

References 43 publications

Supporting

Mentioning

165

Contrasting

Order By: Relevance

“…Met to eIF2 Á GTP is only an order of magnitude higher than for methionyl-tRNA i Met (Kapp and Lorsch 2004). Thus, the defect in aminoacetylating tRNA i Met could provoke the formation of defective complexes between eIF2 Á GTP and uncharged tRNA i Met in gua1-G388D cells.…”

Section: Resultsmentioning

confidence: 93%

“…The K d for Met-tRNA i Met binding to apo-eIF2 is only an order of magnitude higher than for eIF2 Á GTP (Kapp and Lorsch 2004). Hence, eIF2 Á tRNA i Met binary complexes might accumulate if eIF2 cannot compete effectively with other G proteins for the available GTP under conditions of guanine nucleotide limitation.…”

Section: Resultsmentioning

confidence: 99%

“…Met and stimulating the beginning of a new round of initiation (Kapp and Lorsch 2004). This process is inhibited by the phosphorylation of eIF2a in serine 51, a key event in translational regulation under starvation and stress in higher eukaryotes (Pestova et al 2007).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Guanine Nucleotide Pool Imbalance Impairs Multiple Steps of Protein Synthesis and Disrupts GCN4 Translational Control in Saccharomyces cerevisiae

et al. 2011

View full text Add to dashboard Cite

Purine nucleotides are structural components of the genetic material, function as phosphate donors, participate in cellular signaling, are cofactors in enzymatic reactions, and constitute the main carriers of cellular energy. Thus, imbalances in A/G nucleotide biosynthesis affect nearly the whole cellular metabolism and must be tightly regulated. We have identified a substitution mutation (G388D) that reduces the activity of the GMP synthase Gua1 in budding yeast and the total G-nucleotide pool, leading to precipitous reductions in the GDP/GTP ratio and ATP level in vivo. gua1-G388D strongly reduces the rate of growth, impairs general protein synthesis, and derepresses translation of GCN4 mRNA, encoding a transcriptional activator of diverse amino acid biosynthetic enzymes. Although processing of pre-tRNA i Met and other tRNA precursors, and the aminoacylation of tRNA iMet are also strongly impaired in gua1-G388D cells, tRNA i GTP complex (TC) and the multifactor complex (MFC) required for translation initiation accumulate $10-fold in gua1-G388D cells and, to a lesser extent, in wild-type (WT) cells treated with 6-azauracil (6AU). Consistently, addition of an external supply of guanine reverts all the phenotypes of gua1-G388D cells, but not those of gua1-G388D Dhpt1 mutants unable to refill the internal GMP pool through the salvage pathway. These and other findings suggest that a defect in guanine nucleotide biosynthesis evokes a reduction in the rate of general protein synthesis by impairing multiple steps of the process, disrupts the gene-specific reinitiation mechanism for translation of GCN4 mRNA and has far-reaching effects in cell biology and metabolism.

show abstract

Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Guanine Nucleotide Pool Imbalance Impairs Multiple Steps of Protein Synthesis and Disrupts GCN4 Translational Control in Saccharomyces cerevisiae

et al. 2011

View full text Add to dashboard Cite

show abstract

“…In S. cerevisiae, the activity in translation initiation of a mutant initiator tRNA with a G 1 -C 72 base pair is markedly reduced in vivo (45). This mutation was very recently shown to cause a lowering by a factor of 7 of the affinity of an initiator tRNA transcript for yeast eIF2:GTP (47). In the present study, comparison of five methionylated tRNAs (Table I, Role of the ␣ Subunit-As previously shown (21), aIF2␥ forms the structural core of the heterotrimeric aIF2 protein and has a three-dimensional structure markedly close to that of the active EF-Tu:GTP form (41).…”

Section: Discussionmentioning

confidence: 99%

Functional Molecular Mapping of Archaeal Translation Initiation Factor 2

Yatime¹,

Schmitt

Blanquet

et al. 2004

Journal of Biological Chemistry

125

View full text Add to dashboard Cite

Eukaryotic and archaeal initiation factors 2 (e/aIF2) are heterotrimeric proteins (␣␤␥) carrying methionylated initiator tRNA to the small subunit of the ribosome. The three-dimensional structure of aIF2␥ from the Archaea Pyrococcus abyssi was previously solved. This subunit forms the core of the heterotrimer. The ␣ and ␤ subunits bind the ␥, but do not interact together. aIF2␥ shows a high resemblance with elongation factor EF1-A. In this study, we characterize the role of each subunit in the binding of the methionylated initiator tRNA. Studying various aminoacyl-tRNA ligands shows that the methionyl group is a major determinant for recognition by aIF2. aIF2␥ alone is able to specifically bind Met-tRNA i Met , although with a reduced affinity as compared with the intact trimer. Site-directed mutagenesis confirms a binding mode of the tRNA molecule similar to that observed with the elongation factor. Under our assay conditions, aIF2␤ is not involved in the docking of the tRNA molecule. In contrast, aIF2␣ provides the heterotrimer its full tRNA binding affinity. Furthermore, the isolated C-domain of aIF2␣ is responsible for binding of the ␣ subunit to ␥. This binding involves an idiosyncratic loop of domain 2 of aIF2␥. Association of the C-domain of aIF2␣ to aIF2␥ is enough to retrieve the binding affinity of tRNA for aIF2. The N-terminal and central domains of aIF2␣ do not interfere with tRNA binding. However, the N-domain of aIF2␣ interacts with RNA unspecifically. Based on this property, a possible contribution of aIF2␣ to formation of a productive complex between aIF2 and the small ribosomal subunit is envisaged.In the initiation of translation, the recognition of a start codon on a mRNA involves a specialized initiator tRNA. This tRNA is always esterified with methionine. Several proteins, called initiation factors, contribute along with the ribosome to the success of the initiator tRNA-mRNA interaction. Such initiation factors differ in the three domains of life.

show abstract

“…Purified yeast eIF2 binds either GTP (K d $1.7 mM) or GDP (K d $0.02 mM) (Kapp and Lorsch 2004a). As for a number of G proteins, this 100-fold higher affinity for GDP relative to GTP introduces the requirement for eIF2B to recycle eIF2-GDP complexes to the functional eIF2-GTP form.…”

Section: Ternary Complex Formationmentioning

confidence: 99%

Mechanism and Regulation of Protein Synthesis in Saccharomyces cerevisiae

2016

View full text Add to dashboard Cite

In this review, we provide an overview of protein synthesis in the yeast Saccharomyces cerevisiae. The mechanism of protein synthesis is well conserved between yeast and other eukaryotes, and molecular genetic studies in budding yeast have provided critical insights into the fundamental process of translation as well as its regulation. The review focuses on the initiation and elongation phases of protein synthesis with descriptions of the roles of translation initiation and elongation factors that assist the ribosome in binding the messenger RNA (mRNA), selecting the start codon, and synthesizing the polypeptide. We also examine mechanisms of translational control highlighting the mRNA cap-binding proteins and the regulation of GCN4 and CPA1 mRNAs.

show abstract

GTP-dependent Recognition of the Methionine Moiety on Initiator tRNA by Translation Factor eIF2

Cited by 135 publications

References 43 publications

Guanine Nucleotide Pool Imbalance Impairs Multiple Steps of Protein Synthesis and Disrupts GCN4 Translational Control in Saccharomyces cerevisiae

Guanine Nucleotide Pool Imbalance Impairs Multiple Steps of Protein Synthesis and Disrupts GCN4 Translational Control in Saccharomyces cerevisiae

Functional Molecular Mapping of Archaeal Translation Initiation Factor 2

Mechanism and Regulation of Protein Synthesis in Saccharomyces cerevisiae

Contact Info

Product

Resources

About