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Distinct features of cap binding by eIF4E1b proteins.

Kubacka D, Miguel RN, Minshall N, Darzynkiewicz E, Standart N, Zuberek J - J. Mol. Biol. (2014)

Bottom Line: Moreover, eIF4E1b proteins are distinguishable from eIF4E1a by a set of conserved amino acid substitutions, several of which are located near to cap-binding residues.Indeed, eIF4E1b possesses several distinct features, namely, enhancement of cap binding by a benzyl group at N(7) position of guanine, a reduced response to increasing length of the phosphate chain and increased binding to a cap separated by a linker from Sepharose, suggesting differences in the arrangement of the protein's core.In agreement, mutagenesis of the amino acids differentiating eIF4E1b from eIF4E1a reduces cap binding by eIF4E1a 2-fold, demonstrating their role in modulating cap binding.

View Article: PubMed Central - PubMed

Affiliation: Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw 02-089, Poland. Electronic address: dkuba@biogeo.uw.edu.pl.

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Amino acid sequence alignment of vertebrate eIF4E1a and eIF4E1b proteins of H. sapiens, M. musculus, X. laevis and X. tropicalis, D. rerio, B. taurus, R. norvegicus, C. familiaris and G. gallus, performed with CLUSTALW2. Residues in red and blue show negatively and positively charged amino acids within the N-terminus, respectively. The conserved amino acids that distinguish eIF4E1a (gray) and eIF4E1b (black) proteins are highlighted. The amino acids of the eIF4E1a cap-binding pocket and binding sites for eIF4G/4E-BP proteins are marked with circle and triangle symbols, respectively, with green and magenta shading, respectively, showing their conservation. Starred residues indicate the residues whose impact on cap binding we checked experimentally. Secondary structural elements of α-helices (H1–H3) and β-strands (S1–S8) are shown according to the crystal structure of human eIF4E1a in complex with m7GTP or m7GpppA [2].
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f0010: Amino acid sequence alignment of vertebrate eIF4E1a and eIF4E1b proteins of H. sapiens, M. musculus, X. laevis and X. tropicalis, D. rerio, B. taurus, R. norvegicus, C. familiaris and G. gallus, performed with CLUSTALW2. Residues in red and blue show negatively and positively charged amino acids within the N-terminus, respectively. The conserved amino acids that distinguish eIF4E1a (gray) and eIF4E1b (black) proteins are highlighted. The amino acids of the eIF4E1a cap-binding pocket and binding sites for eIF4G/4E-BP proteins are marked with circle and triangle symbols, respectively, with green and magenta shading, respectively, showing their conservation. Starred residues indicate the residues whose impact on cap binding we checked experimentally. Secondary structural elements of α-helices (H1–H3) and β-strands (S1–S8) are shown according to the crystal structure of human eIF4E1a in complex with m7GTP or m7GpppA [2].

Mentions: First, we compared the sequences of eight pairs of vertebrate eIF4E1a/eIF4E1b proteins (Fig. 1). The alignment indicates the α-helical and β-sheet regions that form the core of eIF4E1a proteins and the active-site residues, both for binding the 5′ cap, as well as eIF4G and 4E-BP [1,2]. Xenopus and human eIF4E1a share 84% identical residues, with the main differences located at the N-terminus and a few conservative point mutations dispersed through the rest of the proteins. Importantly, all residues participating in binding the cap and eIF4G are conserved (Fig. 1).


Distinct features of cap binding by eIF4E1b proteins.

Kubacka D, Miguel RN, Minshall N, Darzynkiewicz E, Standart N, Zuberek J - J. Mol. Biol. (2014)

Amino acid sequence alignment of vertebrate eIF4E1a and eIF4E1b proteins of H. sapiens, M. musculus, X. laevis and X. tropicalis, D. rerio, B. taurus, R. norvegicus, C. familiaris and G. gallus, performed with CLUSTALW2. Residues in red and blue show negatively and positively charged amino acids within the N-terminus, respectively. The conserved amino acids that distinguish eIF4E1a (gray) and eIF4E1b (black) proteins are highlighted. The amino acids of the eIF4E1a cap-binding pocket and binding sites for eIF4G/4E-BP proteins are marked with circle and triangle symbols, respectively, with green and magenta shading, respectively, showing their conservation. Starred residues indicate the residues whose impact on cap binding we checked experimentally. Secondary structural elements of α-helices (H1–H3) and β-strands (S1–S8) are shown according to the crystal structure of human eIF4E1a in complex with m7GTP or m7GpppA [2].
© Copyright Policy - CC BY
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4306533&req=5

f0010: Amino acid sequence alignment of vertebrate eIF4E1a and eIF4E1b proteins of H. sapiens, M. musculus, X. laevis and X. tropicalis, D. rerio, B. taurus, R. norvegicus, C. familiaris and G. gallus, performed with CLUSTALW2. Residues in red and blue show negatively and positively charged amino acids within the N-terminus, respectively. The conserved amino acids that distinguish eIF4E1a (gray) and eIF4E1b (black) proteins are highlighted. The amino acids of the eIF4E1a cap-binding pocket and binding sites for eIF4G/4E-BP proteins are marked with circle and triangle symbols, respectively, with green and magenta shading, respectively, showing their conservation. Starred residues indicate the residues whose impact on cap binding we checked experimentally. Secondary structural elements of α-helices (H1–H3) and β-strands (S1–S8) are shown according to the crystal structure of human eIF4E1a in complex with m7GTP or m7GpppA [2].
Mentions: First, we compared the sequences of eight pairs of vertebrate eIF4E1a/eIF4E1b proteins (Fig. 1). The alignment indicates the α-helical and β-sheet regions that form the core of eIF4E1a proteins and the active-site residues, both for binding the 5′ cap, as well as eIF4G and 4E-BP [1,2]. Xenopus and human eIF4E1a share 84% identical residues, with the main differences located at the N-terminus and a few conservative point mutations dispersed through the rest of the proteins. Importantly, all residues participating in binding the cap and eIF4G are conserved (Fig. 1).

Bottom Line: Moreover, eIF4E1b proteins are distinguishable from eIF4E1a by a set of conserved amino acid substitutions, several of which are located near to cap-binding residues.Indeed, eIF4E1b possesses several distinct features, namely, enhancement of cap binding by a benzyl group at N(7) position of guanine, a reduced response to increasing length of the phosphate chain and increased binding to a cap separated by a linker from Sepharose, suggesting differences in the arrangement of the protein's core.In agreement, mutagenesis of the amino acids differentiating eIF4E1b from eIF4E1a reduces cap binding by eIF4E1a 2-fold, demonstrating their role in modulating cap binding.

View Article: PubMed Central - PubMed

Affiliation: Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw 02-089, Poland. Electronic address: dkuba@biogeo.uw.edu.pl.

Show MeSH