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Mutations in the S4–H2 loop of eIF4E which increase the affinity for m 7 GTP
Author(s) -
Spivak-Kroizman Taly,
Friedland Diana E,
De Staercke Christine,
Gernert Kim M,
Goss Dixie J,
Hagedorn Curt H
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)02445-6
Subject(s) - eif4e , gtp' , mutant , nucleotide , microbiology and biotechnology , messenger rna , mutagenesis , biology , chemistry , biochemistry , gene , translation (biology) , enzyme
Eukaryotic initiation factor 4E (eIF4E) binds the 5′‐cap of eukaryotic mRNAs and overexpression of eIF4E in epithelial cell cancers correlates with the metastases/tissue invasion phenotype. Photolabeling of eIF4E with [γ‐ 32 P]8‐azidoguanosine 5′‐triphosphate (8‐N 3 GTP) demonstrated cross‐linking at Lys‐119 in the S4–H2 loop which is distant from the m 7 GTP binding site [Marcotrigiano et al. (1997) Cell 89, 951–961; Friedland et al. (1997) Protein Sci. 6, 125–131]. Modeling studies indicate that 8‐N 3 GTP cross‐linked with Lys‐119 because it binds a site that is occupied by the second nucleotide of a bound mRNA. Mutagenesis of the S4–H2 loop produced proteins with a 5–10‐fold higher affinity for m 7 GTP than wild‐type eIF4E. These mutants of eIF4E may have uses in selectively purifying mRNAs with intact 5′‐ends or in determining how the promyelocytic leukemia protein decreases the affinity of eIF4E for mRNA caps.