Cloning and expression pattern of eukaryotic translation initiation factor 4A of the diamondback moth, Plutella xylostella

Eukaryotic translation initiation factor 4A (eIF4A) is required for a cap-binding complex to recognize the 5′ end of mRNA. A eIF4A gene (Px-eIF4A) was identified from Plutella xylostella. Its full cDNA (1,700 bp) encoded 422 amino acids and showed high sequence similarity (59.6–96.2%) with other insect and human eIF4As. Three dimensional analysis of Px-eIF4A indicated two globular domains, both of which were predicted to participate in RNA binding and helicase activity. Both RT-PCR and Western blotting indicated that the expression of Px-eIF4A showed a constitutive pattern regardless of developmental stage or tissue. An indirect immunofluorescence assay indicated that Px-eIF4A was localized in the cytoplasm. An immunoprecipitation with Px-eIF4A against a protein extract of P. xylostella indicated that Px-eIF4A could bind eIF4G, presumably to form a functional cap-binding complex. These results suggest that Px-eIF4A is constitutively expressed in all tissues and plays a role in the formation of the translation initiation complex in P. xylostella.