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Transduplication resulted in the incorporation of two protein-coding sequences into the turmoil-1 transposable element of C. elegans.

Sela N, Stern A, Makalowski W, Pupko T, Ast G - Biol. Direct (2008)

Bottom Line: Transduplication of protein-coding genes is common in plants, but is unknown of in animals.The ITRs of Turmoil-1 contain a conserved RNA recognition motif (RRM) that originated from the rsp-2 gene and a fragment from the protein-coding region of the cpg-3 gene.Mutations at the 5' splice site of this open reading frame may have reactivated the transduplicated RRM motif.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel. noasela@post.tau.ac.il

ABSTRACT
Transposable elements may acquire unrelated gene fragments into their sequences in a process called transduplication. Transduplication of protein-coding genes is common in plants, but is unknown of in animals. Here, we report that the Turmoil-1 transposable element in C. elegans has incorporated two protein-coding sequences into its inverted terminal repeat (ITR) sequences. The ITRs of Turmoil-1 contain a conserved RNA recognition motif (RRM) that originated from the rsp-2 gene and a fragment from the protein-coding region of the cpg-3 gene. We further report that an open reading frame specific to C. elegans may have been created as a result of a Turmoil-1 insertion. Mutations at the 5' splice site of this open reading frame may have reactivated the transduplicated RRM motif.

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Maximum likelihood tree of the RRM domain. The RRM domain sequence, which is part of the ITR of Turmoil-1, is indicated in red. The tree shows that the RRM domain within Turmoil-1 is derived from the ancestral RRM domain rather than vice versa.
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Figure 2: Maximum likelihood tree of the RRM domain. The RRM domain sequence, which is part of the ITR of Turmoil-1, is indicated in red. The tree shows that the RRM domain within Turmoil-1 is derived from the ancestral RRM domain rather than vice versa.

Mentions: Turmoil-1 is a 5,024-bp long DNA transposon with 760-bp long ITRs and a Harbinger-specific transposase (Figure 1A). These ITRs are unique to Turmoil-1 and are not found in other members of the Harbinger superfamily of DNA transposons [24]. One complete copy of the Turmoil-1 was found on chromosome II of C. elegans; eight Turmoil-1 fragments exist in the genome (for detailed information, see Table 1). An analysis of C. elegans transposable elements [25,26] revealed that a 205-bp ITR sequence within Turmoil-1 is highly similar to a region of two exons separated by an intron of the rsp-2 gene (see pairwise alignment using bl2seq [27] Figure 1B). These two exons encode the RNA Recognition Motif (RRM), which is found in many eukaryal and bacterial proteins. Specifically, the type of RRM domain present in the rsp-2 (called RRM1) gene is highly conserved evolutionarily [28]. The high similarity between the ITR sequence and the fragment of the rsp-2 gene implies that one originated from the other. The antiquity of this domain and a phylogenetic analysis (Figure 2) indicate that Turmoil-1 has recently acquired a portion of the rsp-2 gene sequence into its ITR. Tree reconstruction was performed with the PhyML program version 2.4.5 [29] using among-site rate variation with four discrete rate categories, and the JTT model [30] of sequence evolution.


Transduplication resulted in the incorporation of two protein-coding sequences into the turmoil-1 transposable element of C. elegans.

Sela N, Stern A, Makalowski W, Pupko T, Ast G - Biol. Direct (2008)

Maximum likelihood tree of the RRM domain. The RRM domain sequence, which is part of the ITR of Turmoil-1, is indicated in red. The tree shows that the RRM domain within Turmoil-1 is derived from the ancestral RRM domain rather than vice versa.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2572040&req=5

Figure 2: Maximum likelihood tree of the RRM domain. The RRM domain sequence, which is part of the ITR of Turmoil-1, is indicated in red. The tree shows that the RRM domain within Turmoil-1 is derived from the ancestral RRM domain rather than vice versa.
Mentions: Turmoil-1 is a 5,024-bp long DNA transposon with 760-bp long ITRs and a Harbinger-specific transposase (Figure 1A). These ITRs are unique to Turmoil-1 and are not found in other members of the Harbinger superfamily of DNA transposons [24]. One complete copy of the Turmoil-1 was found on chromosome II of C. elegans; eight Turmoil-1 fragments exist in the genome (for detailed information, see Table 1). An analysis of C. elegans transposable elements [25,26] revealed that a 205-bp ITR sequence within Turmoil-1 is highly similar to a region of two exons separated by an intron of the rsp-2 gene (see pairwise alignment using bl2seq [27] Figure 1B). These two exons encode the RNA Recognition Motif (RRM), which is found in many eukaryal and bacterial proteins. Specifically, the type of RRM domain present in the rsp-2 (called RRM1) gene is highly conserved evolutionarily [28]. The high similarity between the ITR sequence and the fragment of the rsp-2 gene implies that one originated from the other. The antiquity of this domain and a phylogenetic analysis (Figure 2) indicate that Turmoil-1 has recently acquired a portion of the rsp-2 gene sequence into its ITR. Tree reconstruction was performed with the PhyML program version 2.4.5 [29] using among-site rate variation with four discrete rate categories, and the JTT model [30] of sequence evolution.

Bottom Line: Transduplication of protein-coding genes is common in plants, but is unknown of in animals.The ITRs of Turmoil-1 contain a conserved RNA recognition motif (RRM) that originated from the rsp-2 gene and a fragment from the protein-coding region of the cpg-3 gene.Mutations at the 5' splice site of this open reading frame may have reactivated the transduplicated RRM motif.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel. noasela@post.tau.ac.il

ABSTRACT
Transposable elements may acquire unrelated gene fragments into their sequences in a process called transduplication. Transduplication of protein-coding genes is common in plants, but is unknown of in animals. Here, we report that the Turmoil-1 transposable element in C. elegans has incorporated two protein-coding sequences into its inverted terminal repeat (ITR) sequences. The ITRs of Turmoil-1 contain a conserved RNA recognition motif (RRM) that originated from the rsp-2 gene and a fragment from the protein-coding region of the cpg-3 gene. We further report that an open reading frame specific to C. elegans may have been created as a result of a Turmoil-1 insertion. Mutations at the 5' splice site of this open reading frame may have reactivated the transduplicated RRM motif.

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