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Evolution and phylogeny of insect endogenous retroviruses.

Terzian C, Pélisson A, Bucheton A - BMC Evol. Biol. (2001)

Bottom Line: We found that the three phylogenetic trees based respectively on Gag, Pol and Env common motifs are congruent, which suggest a monophyletic origin for these elements.We showed that most of the insect endogenous retroviruses belong to a major clade group which can be further divided into two main subgroups which also differ by the sequence of their primer binding sites (PBS).We propose to name IERV-K and IERV-S these two major subgroups of Insect Endogenous Retro Viruses (or Insect ERrantiVirus, according to the ICTV nomenclature) which respectively use Lys and Ser tRNAs to prime reverse transcription.

View Article: PubMed Central - HTML - PubMed

Affiliation: IGH-CNRS, 141 rue de la Cardonille, Montpellier, France. christophe.terzian@igh.cnrs.fr

ABSTRACT

Background: The genome of invertebrates is rich in retroelements which are structurally reminiscent of the retroviruses of vertebrates. Those containing three open reading frames (ORFs), including an env-like gene, may well be considered as endogenous retroviruses. Further support to this similarity has been provided by the ability of the env-like gene of DmeGypV (the Gypsy endogenous retrovirus of Drosophila melanogaster) to promote infection of Drosophila cells by a pseudotyped vertebrate retrovirus vector.

Results: To gain insights into their evolutionary story, a sample of thirteen insect endogenous retroviruses, which represents the largest sample analysed until now, was studied by computer-assisted comparison of the translated products of their gag, pol and env genes, as well as their LTR structural features. We found that the three phylogenetic trees based respectively on Gag, Pol and Env common motifs are congruent, which suggest a monophyletic origin for these elements.

Conclusions: We showed that most of the insect endogenous retroviruses belong to a major clade group which can be further divided into two main subgroups which also differ by the sequence of their primer binding sites (PBS). We propose to name IERV-K and IERV-S these two major subgroups of Insect Endogenous Retro Viruses (or Insect ERrantiVirus, according to the ICTV nomenclature) which respectively use Lys and Ser tRNAs to prime reverse transcription.

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Multiple alignment of the six motifs common to all Env sequences, except for DmeNomV (see Material and Methods). The numbers in brackets indicate the amino acids between motifs not used in the alignment. The alignment is shaded using to a 50% consensus with gray and black shading indicating similar and identical residues respectively.
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Figure 2: Multiple alignment of the six motifs common to all Env sequences, except for DmeNomV (see Material and Methods). The numbers in brackets indicate the amino acids between motifs not used in the alignment. The alignment is shaded using to a 50% consensus with gray and black shading indicating similar and identical residues respectively.

Mentions: The insect retroviral Env sequences share structural properties with vertebrate retroviral Env proteins: a signal peptide, N-glycosylation sites and a transmembrane domain [13]. It has been shown experimentally that the env gene of DmeGypV, DmeZamV, DanTomV and DmeNomV is expressed from a spliced mRNA [13-16]. Using the MEME program, we have identified six collinear motifs in 12 out of the 13 insect retroviral Env sequences (Fig. 2). Considering the high variability of viral envelope proteins generally described, this strongly suggests that these Env sequences form a monophyletic group. Moreover, the motif II, previously described [6,7], is common to the thirteen Env sequences. The R-X-K-R sequence present at the beginning of this motif was previously described as a common motif present in some insect and vertebrate retro viral Env sequences [14,17]. It is the consensus cleavage site recognized by a cellular endopeptidase that cleaves the precursor envelope protein into the surface (SU) and transmembrane (TM) polypeptides [18].


Evolution and phylogeny of insect endogenous retroviruses.

Terzian C, Pélisson A, Bucheton A - BMC Evol. Biol. (2001)

Multiple alignment of the six motifs common to all Env sequences, except for DmeNomV (see Material and Methods). The numbers in brackets indicate the amino acids between motifs not used in the alignment. The alignment is shaded using to a 50% consensus with gray and black shading indicating similar and identical residues respectively.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC57737&req=5

Figure 2: Multiple alignment of the six motifs common to all Env sequences, except for DmeNomV (see Material and Methods). The numbers in brackets indicate the amino acids between motifs not used in the alignment. The alignment is shaded using to a 50% consensus with gray and black shading indicating similar and identical residues respectively.
Mentions: The insect retroviral Env sequences share structural properties with vertebrate retroviral Env proteins: a signal peptide, N-glycosylation sites and a transmembrane domain [13]. It has been shown experimentally that the env gene of DmeGypV, DmeZamV, DanTomV and DmeNomV is expressed from a spliced mRNA [13-16]. Using the MEME program, we have identified six collinear motifs in 12 out of the 13 insect retroviral Env sequences (Fig. 2). Considering the high variability of viral envelope proteins generally described, this strongly suggests that these Env sequences form a monophyletic group. Moreover, the motif II, previously described [6,7], is common to the thirteen Env sequences. The R-X-K-R sequence present at the beginning of this motif was previously described as a common motif present in some insect and vertebrate retro viral Env sequences [14,17]. It is the consensus cleavage site recognized by a cellular endopeptidase that cleaves the precursor envelope protein into the surface (SU) and transmembrane (TM) polypeptides [18].

Bottom Line: We found that the three phylogenetic trees based respectively on Gag, Pol and Env common motifs are congruent, which suggest a monophyletic origin for these elements.We showed that most of the insect endogenous retroviruses belong to a major clade group which can be further divided into two main subgroups which also differ by the sequence of their primer binding sites (PBS).We propose to name IERV-K and IERV-S these two major subgroups of Insect Endogenous Retro Viruses (or Insect ERrantiVirus, according to the ICTV nomenclature) which respectively use Lys and Ser tRNAs to prime reverse transcription.

View Article: PubMed Central - HTML - PubMed

Affiliation: IGH-CNRS, 141 rue de la Cardonille, Montpellier, France. christophe.terzian@igh.cnrs.fr

ABSTRACT

Background: The genome of invertebrates is rich in retroelements which are structurally reminiscent of the retroviruses of vertebrates. Those containing three open reading frames (ORFs), including an env-like gene, may well be considered as endogenous retroviruses. Further support to this similarity has been provided by the ability of the env-like gene of DmeGypV (the Gypsy endogenous retrovirus of Drosophila melanogaster) to promote infection of Drosophila cells by a pseudotyped vertebrate retrovirus vector.

Results: To gain insights into their evolutionary story, a sample of thirteen insect endogenous retroviruses, which represents the largest sample analysed until now, was studied by computer-assisted comparison of the translated products of their gag, pol and env genes, as well as their LTR structural features. We found that the three phylogenetic trees based respectively on Gag, Pol and Env common motifs are congruent, which suggest a monophyletic origin for these elements.

Conclusions: We showed that most of the insect endogenous retroviruses belong to a major clade group which can be further divided into two main subgroups which also differ by the sequence of their primer binding sites (PBS). We propose to name IERV-K and IERV-S these two major subgroups of Insect Endogenous Retro Viruses (or Insect ERrantiVirus, according to the ICTV nomenclature) which respectively use Lys and Ser tRNAs to prime reverse transcription.

Show MeSH
Related in: MedlinePlus