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Crystal structure of the eukaryotic translation initiation factor 2A from Schizosaccharomyces pombe.

Kashiwagi K, Ito T, Yokoyama S - J. Struct. Funct. Genomics (2014)

Bottom Line: The structure adopts a novel nine-bladed β-propeller fold.In contrast to the usual β-propeller proteins, the central channel of the molecule has the narrower opening on the bottom of the protein and the wider opening on the top.Highly conserved residues are concentrated in the positively-charged top face, suggesting the importance of this face for interactions with nucleic acids or other initiation factors.

View Article: PubMed Central - PubMed

Affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

ABSTRACT
The eukaryotic translation initiation factor 2A (eIF2A) was identified as a factor that stimulates the binding of methionylated initiator tRNA (Met-tRNA i (Met) ) to the 40S ribosomal subunit, but its physiological role remains poorly defined. Recently, eIF2A was shown to be involved in unconventional translation initiation from CUG codons and in viral protein synthesis under stress conditions where eIF2 is inactivated. We determined the crystal structure of the WD-repeat domain of Schizosaccharomyces pombe eIF2A at 2.5 Å resolution. The structure adopts a novel nine-bladed β-propeller fold. In contrast to the usual β-propeller proteins, the central channel of the molecule has the narrower opening on the bottom of the protein and the wider opening on the top. Highly conserved residues are concentrated in the positively-charged top face, suggesting the importance of this face for interactions with nucleic acids or other initiation factors.

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Crystal structure of the WD-repeat domain from S. pombe eIF2A (eIF2A-WD). a Top view of the structure of eIF2A-WD. Only molecule A in the asymmetric unit is shown hereafter. b Side view and schematic representation of the structure of eIF2A-WD. c An example of the canonical seven-bladed β-propeller protein (the WD-repeat region of G protein Giβ1, PDB ID: 1GP2 [23] ) and schematic representation of the structure. d The alignment of the nine blades of eIF2A-WD
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Fig1: Crystal structure of the WD-repeat domain from S. pombe eIF2A (eIF2A-WD). a Top view of the structure of eIF2A-WD. Only molecule A in the asymmetric unit is shown hereafter. b Side view and schematic representation of the structure of eIF2A-WD. c An example of the canonical seven-bladed β-propeller protein (the WD-repeat region of G protein Giβ1, PDB ID: 1GP2 [23] ) and schematic representation of the structure. d The alignment of the nine blades of eIF2A-WD

Mentions: The full length S. pombe eIF2A (576 amino acids) was readily expressed in E. coli, but crystallization trials were not successful. Since the C-terminal region of eIF2A is predicted to be highly disordered, we prepared a C-terminally truncated eIF2A (residues 1–424). We successfully crystallized this truncated eIF2A, and the diffraction quality of the crystals was sufficient for a crystallographic model-building analysis. We determined the crystal structure of the C-terminally truncated eIF2A at 2.5 Å resolution (Table 1, Fig. 1a, b). The final model consists of residues 3–234, 242–248, and 256–412. The crystal structure of the truncated eIF2A revealed that it adopts a nine-bladed β-propeller fold, with the same overall topology as the regular β-propeller proteins, involving circularly arranged repeats of a four-stranded antiparallel β-sheet motif (Fig. 1a). The entire assigned region participates in the formation of the β-propeller structure, and therefore it is appropriate to define this region as the WD-repeat domain of eIF2A (eIF2A-WD). Most β-propeller proteins contain six to eight blades, and the three-dimensional structures of four- to eight-, and ten-bladed β-propellers have been determined. To our knowledge, this is the first example of a nine-bladed β-propeller protein.Table 1


Crystal structure of the eukaryotic translation initiation factor 2A from Schizosaccharomyces pombe.

Kashiwagi K, Ito T, Yokoyama S - J. Struct. Funct. Genomics (2014)

Crystal structure of the WD-repeat domain from S. pombe eIF2A (eIF2A-WD). a Top view of the structure of eIF2A-WD. Only molecule A in the asymmetric unit is shown hereafter. b Side view and schematic representation of the structure of eIF2A-WD. c An example of the canonical seven-bladed β-propeller protein (the WD-repeat region of G protein Giβ1, PDB ID: 1GP2 [23] ) and schematic representation of the structure. d The alignment of the nine blades of eIF2A-WD
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4125824&req=5

Fig1: Crystal structure of the WD-repeat domain from S. pombe eIF2A (eIF2A-WD). a Top view of the structure of eIF2A-WD. Only molecule A in the asymmetric unit is shown hereafter. b Side view and schematic representation of the structure of eIF2A-WD. c An example of the canonical seven-bladed β-propeller protein (the WD-repeat region of G protein Giβ1, PDB ID: 1GP2 [23] ) and schematic representation of the structure. d The alignment of the nine blades of eIF2A-WD
Mentions: The full length S. pombe eIF2A (576 amino acids) was readily expressed in E. coli, but crystallization trials were not successful. Since the C-terminal region of eIF2A is predicted to be highly disordered, we prepared a C-terminally truncated eIF2A (residues 1–424). We successfully crystallized this truncated eIF2A, and the diffraction quality of the crystals was sufficient for a crystallographic model-building analysis. We determined the crystal structure of the C-terminally truncated eIF2A at 2.5 Å resolution (Table 1, Fig. 1a, b). The final model consists of residues 3–234, 242–248, and 256–412. The crystal structure of the truncated eIF2A revealed that it adopts a nine-bladed β-propeller fold, with the same overall topology as the regular β-propeller proteins, involving circularly arranged repeats of a four-stranded antiparallel β-sheet motif (Fig. 1a). The entire assigned region participates in the formation of the β-propeller structure, and therefore it is appropriate to define this region as the WD-repeat domain of eIF2A (eIF2A-WD). Most β-propeller proteins contain six to eight blades, and the three-dimensional structures of four- to eight-, and ten-bladed β-propellers have been determined. To our knowledge, this is the first example of a nine-bladed β-propeller protein.Table 1

Bottom Line: The structure adopts a novel nine-bladed β-propeller fold.In contrast to the usual β-propeller proteins, the central channel of the molecule has the narrower opening on the bottom of the protein and the wider opening on the top.Highly conserved residues are concentrated in the positively-charged top face, suggesting the importance of this face for interactions with nucleic acids or other initiation factors.

View Article: PubMed Central - PubMed

Affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

ABSTRACT
The eukaryotic translation initiation factor 2A (eIF2A) was identified as a factor that stimulates the binding of methionylated initiator tRNA (Met-tRNA i (Met) ) to the 40S ribosomal subunit, but its physiological role remains poorly defined. Recently, eIF2A was shown to be involved in unconventional translation initiation from CUG codons and in viral protein synthesis under stress conditions where eIF2 is inactivated. We determined the crystal structure of the WD-repeat domain of Schizosaccharomyces pombe eIF2A at 2.5 Å resolution. The structure adopts a novel nine-bladed β-propeller fold. In contrast to the usual β-propeller proteins, the central channel of the molecule has the narrower opening on the bottom of the protein and the wider opening on the top. Highly conserved residues are concentrated in the positively-charged top face, suggesting the importance of this face for interactions with nucleic acids or other initiation factors.

Show MeSH
Related in: MedlinePlus