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Parallel relaxation of stringent RNA recognition in plant and mammalian L1 retrotransposons.

Ohshima K - Mol. Biol. Evol. (2012)

Bottom Line: L1 elements are mammalian non-long terminal repeat retrotransposons, or long interspersed elements (LINEs), that significantly influence the dynamics and fluidity of the genome.This strongly suggests that plant LINEs require a particular 3'-end sequence during initiation of reverse transcription.As one L1-clade LINE was also found to share the 3'-end sequence with a SINE in a green algal genome, I propose that the ancestral L1-clade LINE in the common ancestor of green plants may have recognized the specific RNA template, with stringent recognition then becoming relaxed during the course of plant evolution.

View Article: PubMed Central - PubMed

ABSTRACT
L1 elements are mammalian non-long terminal repeat retrotransposons, or long interspersed elements (LINEs), that significantly influence the dynamics and fluidity of the genome. A series of observations suggest that plant L1-clade LINEs, just as mammalian L1s, mobilize both short interspersed elements (SINEs) and certain messenger RNA by recognizing the 3'-poly(A) tail of RNA. However, one L1 lineage in monocots was shown to possess a conserved 3'-end sequence with a solid RNA structure also observed in maize and sorghum SINEs. This strongly suggests that plant LINEs require a particular 3'-end sequence during initiation of reverse transcription. As one L1-clade LINE was also found to share the 3'-end sequence with a SINE in a green algal genome, I propose that the ancestral L1-clade LINE in the common ancestor of green plants may have recognized the specific RNA template, with stringent recognition then becoming relaxed during the course of plant evolution.

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Proposed model for the 3′-end recognition of L1-clade LINEs. The ancestral L1-clade LINE in the ancestral green plant possessed a stringent, nonmammalian-type RNA recognition property. During the course of plant evolution, a L1 lineage(s) lost the ability to specifically recognize the RNA template for reverse transcription, introducing relaxed 3′-end recognition in land plants. Processed pseudogenes have been reported in eudicots, monocots, and mammals. ME1-3: plant L1 lineages; (e): eudicots; (m): monocots; M, F: vertebrate L1 lineages; (m): mammals; (f): fish.
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mss147-F3: Proposed model for the 3′-end recognition of L1-clade LINEs. The ancestral L1-clade LINE in the ancestral green plant possessed a stringent, nonmammalian-type RNA recognition property. During the course of plant evolution, a L1 lineage(s) lost the ability to specifically recognize the RNA template for reverse transcription, introducing relaxed 3′-end recognition in land plants. Processed pseudogenes have been reported in eudicots, monocots, and mammals. ME1-3: plant L1 lineages; (e): eudicots; (m): monocots; M, F: vertebrate L1 lineages; (m): mammals; (f): fish.

Mentions: The last example of a SINE/LINE pair in the L1-clade was found in a green alga. The 3′-end sequence (ca., 80 nucleotides) of Chlamydomonas SINEX-3_CR (Cognat et al. 2008) was very similar to that of L1-1_CR, with both ending in poly(A) repeats (supplementary fig. S11, Supplementary Material online). As land plants emerged from green algae (Karol et al. 2001), the following is proposed for 3′-end recognition of plant L1-clade LINEs (fig. 3). It is possible that the ancestral L1-clade LINE in the genome of the common ancestor of green plants possessed stringent, nonmammalian-type RNA recognition properties. During the course of plant evolution, a L1 lineage(s) then lost the ability to specifically recognize the RNA template for reverse transcription, thereby introducing relaxed 3′-end recognition in land (flowering) plants as in mammals. As horizontal transfer of LINEs between eukaryotes is rare (Kordiš and Gubenšek 1998; Malik et al. 1999), the discontinuous distribution of L1-clade LINEs with low specificity (i.e., mammalian L1s and plant ME2/ME3) suggests a type of parallel evolution.Fig. 3.


Parallel relaxation of stringent RNA recognition in plant and mammalian L1 retrotransposons.

Ohshima K - Mol. Biol. Evol. (2012)

Proposed model for the 3′-end recognition of L1-clade LINEs. The ancestral L1-clade LINE in the ancestral green plant possessed a stringent, nonmammalian-type RNA recognition property. During the course of plant evolution, a L1 lineage(s) lost the ability to specifically recognize the RNA template for reverse transcription, introducing relaxed 3′-end recognition in land plants. Processed pseudogenes have been reported in eudicots, monocots, and mammals. ME1-3: plant L1 lineages; (e): eudicots; (m): monocots; M, F: vertebrate L1 lineages; (m): mammals; (f): fish.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472496&req=5

mss147-F3: Proposed model for the 3′-end recognition of L1-clade LINEs. The ancestral L1-clade LINE in the ancestral green plant possessed a stringent, nonmammalian-type RNA recognition property. During the course of plant evolution, a L1 lineage(s) lost the ability to specifically recognize the RNA template for reverse transcription, introducing relaxed 3′-end recognition in land plants. Processed pseudogenes have been reported in eudicots, monocots, and mammals. ME1-3: plant L1 lineages; (e): eudicots; (m): monocots; M, F: vertebrate L1 lineages; (m): mammals; (f): fish.
Mentions: The last example of a SINE/LINE pair in the L1-clade was found in a green alga. The 3′-end sequence (ca., 80 nucleotides) of Chlamydomonas SINEX-3_CR (Cognat et al. 2008) was very similar to that of L1-1_CR, with both ending in poly(A) repeats (supplementary fig. S11, Supplementary Material online). As land plants emerged from green algae (Karol et al. 2001), the following is proposed for 3′-end recognition of plant L1-clade LINEs (fig. 3). It is possible that the ancestral L1-clade LINE in the genome of the common ancestor of green plants possessed stringent, nonmammalian-type RNA recognition properties. During the course of plant evolution, a L1 lineage(s) then lost the ability to specifically recognize the RNA template for reverse transcription, thereby introducing relaxed 3′-end recognition in land (flowering) plants as in mammals. As horizontal transfer of LINEs between eukaryotes is rare (Kordiš and Gubenšek 1998; Malik et al. 1999), the discontinuous distribution of L1-clade LINEs with low specificity (i.e., mammalian L1s and plant ME2/ME3) suggests a type of parallel evolution.Fig. 3.

Bottom Line: L1 elements are mammalian non-long terminal repeat retrotransposons, or long interspersed elements (LINEs), that significantly influence the dynamics and fluidity of the genome.This strongly suggests that plant LINEs require a particular 3'-end sequence during initiation of reverse transcription.As one L1-clade LINE was also found to share the 3'-end sequence with a SINE in a green algal genome, I propose that the ancestral L1-clade LINE in the common ancestor of green plants may have recognized the specific RNA template, with stringent recognition then becoming relaxed during the course of plant evolution.

View Article: PubMed Central - PubMed

ABSTRACT
L1 elements are mammalian non-long terminal repeat retrotransposons, or long interspersed elements (LINEs), that significantly influence the dynamics and fluidity of the genome. A series of observations suggest that plant L1-clade LINEs, just as mammalian L1s, mobilize both short interspersed elements (SINEs) and certain messenger RNA by recognizing the 3'-poly(A) tail of RNA. However, one L1 lineage in monocots was shown to possess a conserved 3'-end sequence with a solid RNA structure also observed in maize and sorghum SINEs. This strongly suggests that plant LINEs require a particular 3'-end sequence during initiation of reverse transcription. As one L1-clade LINE was also found to share the 3'-end sequence with a SINE in a green algal genome, I propose that the ancestral L1-clade LINE in the common ancestor of green plants may have recognized the specific RNA template, with stringent recognition then becoming relaxed during the course of plant evolution.

Show MeSH
Related in: MedlinePlus