The Distribution of eIF4E-Family Members across Insecta

Abstract

Insects are part of the earliest faunas that invaded terrestrial environments and are the first organisms that evolved controlled flight. Nowadays, insects are the most diverse animal group on the planet and comprise the majority of extant animal species described. Moreover, they have a huge impact in the biosphere as well as in all aspects of human life and economy; therefore understanding all aspects of insect biology is of great importance. In insects, as in all cells, translation is a fundamental process for gene expression. However, translation in insects has been mostly studied only in the model organism Drosophila melanogaster. We used all publicly available genomic sequences to investigate in insects the distribution of the genes encoding the cap-binding protein eIF4E, a protein that plays a crucial role in eukaryotic translation. We found that there is a diversity of multiple ortholog genes encoding eIF4E isoforms within the genus Drosophila. In striking contrast, insects outside this genus contain only a single eIF4E gene, related to D. melanogaster eIF4E-1. We also found that all insect species here analyzed contain only one Class II gene, termed 4E-HP. We discuss the possible evolutionary causes originating the multiplicity of eIF4E genes within the genus Drosophila.

Figure 1

Seven eIF4E cognates in D. melanogaster. (A) ClustalW alignment of amino acid sequences representing Class I eIF4E family members from D. melanogaster. An extended version of eIF4E-6, not detected in previous studies, is included. Identical (blue) or conservative (gray) amino acid residues in at least 70% of sequences are highlighted. Conservative substitutions groups are STA, or NEQK, or NHQK, or NDEQ, or QHRK, or MILV, or MILF, or HY, or FYW, or GA. Residues essential for eIF4G- and 4E-BP binding are marked ∗; residues involved in cap binding are marked lower case c; phosphorylatable Ser, as well as Lys described to form a salt bridge with P-Ser, are marked lower case p.

Figure 2

ClustalW alignment of amino acid sequences of eIF4E-1 orthologs from species of the genus Drosophila.

Figure 3

ClustalW alignment of amino acid sequences of eIF4E-3 orthologs from species of the genus Drosophila.

Figure 4

ClustalW alignment of amino acid sequences of eIF4E-4 orthologs from species of the genus Drosophila.

Figure 5

ClustalW alignment of amino acid sequences of eIF4E-5 orthologs from species of the genus Drosophila.

Figure 6

ClustalW alignment of amino acid sequences of eIF4E-6 orthologs from species of the genus Drosophila.

Figure 7

ClustalW alignment of amino acid sequences of eIF4E-7 orthologs from species of the genus Drosophila.

Figure 8

Radial phylogram computed from sequence alignments of eIF4Es from Drosophila species.

Figure 9

Orthologs of D. melanogaster eIF4E-1 in other insects. ClustalW alignment of amino acid sequences of eIF4E-1 orthologs from diverse insect species.

Figure 10

Phylogram computed from sequence alignments of eIF4E-1 from diverse insect species.

Figure 11

ClustalW alignment of amino acid sequences of 4E-HP orthologs from species of the genus Drosophila.

Figure 12

Orthologs of D. melanogaster 4E-HP in diverse insect species. ClustalW alignment of amino acid sequences of 4E-HP orthologs from diverse insect species.

Figure 13

Phylogram computed from sequence alignments of 4E-HP from diverse insect species.