scholarly journals Coordination of Eukaryotic Translation Elongation Factor 1A (eEF1A) Function in Actin Organization and Translation Elongation by the Guanine Nucleotide Exchange Factor eEF1Bα

2008 ◽  
Vol 284 (7) ◽  
pp. 4739-4747 ◽  
Author(s):  
Yvette R. Pittman ◽  
Kimberly Kandl ◽  
Marcus Lewis ◽  
Louis Valente ◽  
Terri Goss Kinzy
Keyword(s):  
Elongation Factor ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Translation Elongation Factor ◽  
Translation Elongation ◽  
Eukaryotic Translation ◽  
Actin Organization ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Translation Elongation Factor 1A

scholarly journals Mapping the human translation elongation factor eEF1H complex using the yeast two-hybrid system

2002 ◽  
Vol 365 (3) ◽  
pp. 669-676 ◽  
Author(s):  
Francisco MANSILLA ◽  
Irene FRIIS ◽  
Mandana JADIDI ◽  
Karen M. NIELSEN ◽  
Brian F.C. CLARK ◽  
...  
Keyword(s):  
Elongation Factor ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Translation Elongation Factor ◽  
Yeast Two Hybrid ◽  
Translation Elongation ◽  
Guanine Nucleotide Exchange ◽  
Yeast Two Hybrid System ◽  
Two Hybrid

In eukaryotes, the eukaryotic translation elongation factor eEF1A responsible for transporting amino-acylated tRNA to the ribosome forms a higher-order complex, eEF1H, with its guanine-nucleotide-exchange factor eEF1B. In metazoans, eEF1B consists of three subunits: eEF1Bα, eEF1Bβ and eEF1Bγ. The first two subunits possess the nucleotide-exchange activity, whereas the role of the last remains poorly defined. In mammals, two active tissue-specific isoforms of eEF1A have been identified. The reason for this pattern of differential expression is unknown. Several models on the basis of in vitro experiments have been proposed for the macromolecular organization of the eEF1H complex. However, these models differ in various aspects. This might be due to the difficulties of handling, particularly the eEF1Bβ and eEF1Bγ subunits in vitro. Here, the human eEF1H complex is for the first time mapped using the yeast two-hybrid system, which is a powerful in vivo technique for analysing protein—protein interactions. The following complexes were observed: eEF1A1:eEF1Bα, eEF1A1:eEF1Bβ, eEF1Bβ:eEF1Bβ, eEF1Bα:eEF1Bγ, eEF1Bβ:eEF1Bγ and eEF1Bα:eEF1Bγ:eEF1Bβ, where the last was observed using a three-hybrid approach. Surprisingly, eEF1A2 showed no or only little affinity for the guanine-nucleotide-exchange factors. Truncated versions of the subunits of eEF1B were used to orientate these subunits within the resulting model. The model unit is a pentamer composed of two molecules of eEF1A, each interacting with either eEF1Bα or eEF1Bβ held together by eEF1Bγ. These units can dimerize via eEF1Bβ. Our model is compared with other models, and structural as well as functional aspects of the model are discussed.

scholarly journals Overexpression of Translation Elongation Factor 1A Affects the Organization and Function of the Actin Cytoskeleton in Yeast

Genetics ◽  
2001 ◽  
Vol 157 (4) ◽  
pp. 1425-1436
Author(s):  
Raj Munshi ◽  
Kimberly A Kandl ◽  
Anne Carr-Schmid ◽  
Johanna L Whitacre ◽  
Alison E M Adams ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Elongation Factor ◽  
Nucleotide Exchange ◽  
Translation Elongation Factor ◽  
Translation Elongation ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
And Function

Abstract The translation elongation factor 1 complex (eEF1) plays a central role in protein synthesis, delivering aminoacyl-tRNAs to the elongating ribosome. The eEF1A subunit, a classic G-protein, also performs roles aside from protein synthesis. The overexpression of either eEF1A or eEF1Bα, the catalytic subunit of the guanine nucleotide exchange factor, in Saccharomyces cerevisiae results in effects on cell growth. Here we demonstrate that overexpression of either factor does not affect the levels of the other subunit or the rate or accuracy of protein synthesis. Instead, the major effects in vivo appear to be at the level of cell morphology and budding. eEF1A overexpression results in dosage-dependent reduced budding and altered actin distribution and cellular morphology. In addition, the effects of excess eEF1A in actin mutant strains show synthetic growth defects, establishing a genetic connection between the two proteins. As the ability of eEF1A to bind and bundle actin is conserved in yeast, these results link the established ability of eEF1A to bind and bundle actin in vitro with nontranslational roles for the protein in vivo.

scholarly journals Evidence That Eukaryotic Translation Elongation Factor 1A (eEF1A) Binds the Gcn2 Protein C Terminus and Inhibits Gcn2 Activity

2011 ◽  
Vol 286 (42) ◽  
pp. 36568-36579 ◽  
Author(s):  
Jyothsna Visweswaraiah ◽  
Sebastien Lageix ◽  
Beatriz A. Castilho ◽  
Lara Izotova ◽  
Terri Goss Kinzy ◽  
...  
Keyword(s):  
Protein C ◽  
Elongation Factor ◽  
Translation Elongation Factor ◽  
Translation Elongation ◽  
Eukaryotic Translation ◽  
C Terminus ◽  
Translation Elongation Factor 1A

scholarly journals Guanine nucleotide exchange factor for eukaryotic translation initiation factor 2 in Saccharomyces cerevisiae: interactions between the essential subunits GCD2, GCD6, and GCD7 and the regulatory subunit GCN3.

1993 ◽  
Vol 13 (8) ◽  
pp. 4618-4631 ◽  
Author(s):  
J L Bushman ◽  
M Foiani ◽  
A M Cigan ◽  
C J Paddon ◽  
A G Hinnebusch
Keyword(s):  
Translation Initiation ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Eukaryotic Translation ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Initiation Factor 2 ◽  
Eukaryotic Translation Initiation

Phosphorylation of eukaryotic translation initiation factor 2 (eIF-2) in amino acid-starved cells of the yeast Saccharomyces cerevisiae reduces general protein synthesis but specifically stimulates translation of GCN4 mRNA. This regulatory mechanism is dependent on the nonessential GCN3 protein and multiple essential proteins encoded by GCD genes. Previous genetic and biochemical experiments led to the conclusion that GCD1, GCD2, and GCN3 are components of the GCD complex, recently shown to be the yeast equivalent of the mammalian guanine nucleotide exchange factor for eIF-2, known as eIF-2B. In this report, we identify new constituents of the GCD-eIF-2B complex and probe interactions between its different subunits. Biochemical evidence is presented that GCN3 is an integral component of the GCD-eIF-2B complex that, while dispensable, can be mutationally altered to have a substantial inhibitory effect on general translation initiation. The amino acid sequence changes for three gcd2 mutations have been determined, and we describe several examples of mutual suppression involving the gcd2 mutations and particular alleles of GCN3. These allele-specific interactions have led us to propose that GCN3 and GCD2 directly interact in the GCD-eIF-2B complex. Genetic evidence that GCD6 and GCD7 encode additional subunits of the GCD-eIF-2B complex was provided by the fact that reduced-function mutations in these genes are lethal in strains deleted for GCN3, the same interaction described previously for mutations in GCD1 and GCD2. Biochemical experiments showing that GCD6 and GCD7 copurify and coimmunoprecipitate with GCD1, GCD2, GCN3, and subunits of eIF-2 have confirmed that GCD6 and GCD7 are subunits of the GCD-eIF-2B complex. The fact that all five subunits of yeast eIF-2B were first identified as translational regulators of GCN4 strongly suggests that regulation of guanine nucleotide exchange on eIF-2 is a key control point for translation in yeast cells just as in mammalian cells.

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