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Eukaryotic translation initiation factor eIF5 promotes the accuracy of start codon recognition by regulating Pi release and conformational transitions of the preinitiation complex.

Saini AK, Nanda JS, Martin-Marcos P, Dong J, Zhang F, Bhardwaj M, Lorsch JR, Hinnebusch AG - Nucleic Acids Res. (2014)

Bottom Line: Suppressor G62S mitigates both defects of G31R, accounting for its efficient suppression of UUG initiation in G31R,G62S cells; however suppressor M18V impairs GTP hydrolysis with little effect on PIC conformation.The strong defect in GTP hydrolysis conferred by M18V likely explains its broad suppression of Sui(-) mutations in numerous factors.We conclude that both of eIF5's functions, regulating Pi release and stabilizing the closed PIC conformation, contribute to stringent AUG selection in vivo.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Gene Regulation and Development, Eunice K. Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA Laboratory on the Mechanism and Regulation of Protein Synthesis, Eunice K. Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA sainiade@gmail.com.

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Locations of yeast eIF5 residues altered by Sui− or Ssu− substitutions in the solution structure of the human eIF5-NTD. Ribbon (A and C) and surface (B and D) representations of the human eIF5-NTD were rendered using PyMol from pdb file 2G2K (7) with the locations of residues aligning with the indicated yeast residues colored red, green or black and also shown in stick representation (A and C).
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Figure 6: Locations of yeast eIF5 residues altered by Sui− or Ssu− substitutions in the solution structure of the human eIF5-NTD. Ribbon (A and C) and surface (B and D) representations of the human eIF5-NTD were rendered using PyMol from pdb file 2G2K (7) with the locations of residues aligning with the indicated yeast residues colored red, green or black and also shown in stick representation (A and C).

Mentions: Our finding that the eIF5-M18V substitution strongly impairs GTP hydrolysis and Pi release in the PIC fits with its location only three residues from Arg-15 in the NTT of eIF5 (Figure 6A and B). Arg fingers are usually flanked by hydrophobic residues that stabilize the Arg finger loop and, indeed, R15 is flanked by Phe and Tyr residues: F13Y14R15Y16K17M18 ((7) and references therein). As M18V replaces one flanking hydrophobic residue with another, it would not necessarily perturb hypothetical packing of the Arg finger loop with the core of the GAP domain, but perhaps the Val substitution disturbs the orientation of Arg-15 in a manner that reduces its ability to stimulate GTP hydrolysis.


Eukaryotic translation initiation factor eIF5 promotes the accuracy of start codon recognition by regulating Pi release and conformational transitions of the preinitiation complex.

Saini AK, Nanda JS, Martin-Marcos P, Dong J, Zhang F, Bhardwaj M, Lorsch JR, Hinnebusch AG - Nucleic Acids Res. (2014)

Locations of yeast eIF5 residues altered by Sui− or Ssu− substitutions in the solution structure of the human eIF5-NTD. Ribbon (A and C) and surface (B and D) representations of the human eIF5-NTD were rendered using PyMol from pdb file 2G2K (7) with the locations of residues aligning with the indicated yeast residues colored red, green or black and also shown in stick representation (A and C).
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Related In: Results  -  Collection

Show All Figures
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Figure 6: Locations of yeast eIF5 residues altered by Sui− or Ssu− substitutions in the solution structure of the human eIF5-NTD. Ribbon (A and C) and surface (B and D) representations of the human eIF5-NTD were rendered using PyMol from pdb file 2G2K (7) with the locations of residues aligning with the indicated yeast residues colored red, green or black and also shown in stick representation (A and C).
Mentions: Our finding that the eIF5-M18V substitution strongly impairs GTP hydrolysis and Pi release in the PIC fits with its location only three residues from Arg-15 in the NTT of eIF5 (Figure 6A and B). Arg fingers are usually flanked by hydrophobic residues that stabilize the Arg finger loop and, indeed, R15 is flanked by Phe and Tyr residues: F13Y14R15Y16K17M18 ((7) and references therein). As M18V replaces one flanking hydrophobic residue with another, it would not necessarily perturb hypothetical packing of the Arg finger loop with the core of the GAP domain, but perhaps the Val substitution disturbs the orientation of Arg-15 in a manner that reduces its ability to stimulate GTP hydrolysis.

Bottom Line: Suppressor G62S mitigates both defects of G31R, accounting for its efficient suppression of UUG initiation in G31R,G62S cells; however suppressor M18V impairs GTP hydrolysis with little effect on PIC conformation.The strong defect in GTP hydrolysis conferred by M18V likely explains its broad suppression of Sui(-) mutations in numerous factors.We conclude that both of eIF5's functions, regulating Pi release and stabilizing the closed PIC conformation, contribute to stringent AUG selection in vivo.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Gene Regulation and Development, Eunice K. Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA Laboratory on the Mechanism and Regulation of Protein Synthesis, Eunice K. Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA sainiade@gmail.com.

Show MeSH
Related in: MedlinePlus