Molecular characterization and phylogenetic analysis of the eukaryotic translation initiation factor 4A gene in Antheraea pernyi (Lepdoptera: Saturniidae)

Abstract

Eukaryotic initiation factor 4A (eIF-4A) is an essential component for protein translation in eukaryotes. The eIF-4A gene (ApeIF-4A) was isolated and characterized from Antheraea pernyi (Guérin-Méneville) (Lepidoptera: Saturniidae). The obtained cDNA sequence was 1,435-bp long with an open reading frame of 1,266 bp encoding 421 amino acids. The predicted amino acid sequence shared several conserved features as found in known eIF-4As and revealed 74 and 78% identities with eIF-4As of Homo sapiens L. and Drosophila melanogaster (Meigen), respectively. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that ApeIF-4A was transcribed at four developmental stages and in all tissues tested, suggesting that it plays an important role in development of A. pernyi. Homologous alignment suggested that eIF-4As are highly conserved throughout evolution of eukaryote organisms. Phylogenetic trees based on the amino acid and nucleotide sequences of eIF-4A demonstrated a similar topology with the classical systematics, suggesting that it has the potential value in phylogenetic inference of eukaryotes.

Keywords: Antheraea pernyi; eukaryotic initiation factor 4A; expression pattern; phylogenetic inference.

Fig. 1.

The complete nucleotide and deduced amino acid sequence of the A. pernyi eIF-4A gene. (A) cDNA sequence and deduced amino acid sequence of A. pernyi eIF-4A gene. The initiation codon ATG is bolded and the termination codon TAG is bolded and marked with an asterisk. The conserved region DEADc positioned at 50-250 is shaded and HELICc positioned at 261-372 is underlined. (B) The predicted conserved features of A. pernyi eIF-4A, including the ATP-binding site, the Mg ⁺⁺ -binding site (DEAD box), the nucleotide binding region, and the motif III.

Fig. 2.

Expression patterns of the A. pernyi eIF-4A gene (A) during the four developmental stages and (B) in various tissues of the fifth stage larvae; 1–4 represents egg, larva, pupa and moth, respectively, and 5–14 represents hemolymph, fat body, midgut, silk glands, integument, Malpighian tubules, testes, ovaries, brain and muscle, respectively.

Fig. 3.

Sequence comparisons of eIF-4As. The eIF-4A sequences from A. pernyi (AGK45314), B. mori (ABF51379), Dr. melanogaster (NP_476595), H. sapiens (NP_001407), Da. rerio (NP_938180), Ar. thaliana (NP_566469), O. sativa (NP_001058481), and S. cerevisiae are aligned. The sign # shows the position of the ATP-binding site, sign * shows the position of the Mg ⁺⁺ -binding site, sign % shows the position of the nucleotide binding region, and sign $ shows the position of the motif III that is involved in coupling ATP hydrolysis to RNA binding.

Fig. 4.

Maximum-likelihood trees based on the amino acid (A) and nucleotide (B) sequence comparisons of the eIF-4A genes. Numbers at nodes are bootstrap P values.