Limits...
Transposition-mediated DNA re-replication in maize.

Zhang J, Zuo T, Wang D, Peterson T - Elife (2014)

Bottom Line: Every DNA segment in a eukaryotic genome normally replicates once and only once per cell cycle to maintain genome stability.The DNA re-replication can spontaneously abort to generate double-strand breaks, which can be repaired to generate Composite Insertions composed of transposon termini flanking segmental duplications of various lengths.These results show how alternative transposition coupled with DNA replication and repair can significantly alter genome structure and may have contributed to rapid genome evolution in maize and possibly other eukaryotes.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Development and Cell Biology, Iowa State University, Ames, United States.

ABSTRACT
Every DNA segment in a eukaryotic genome normally replicates once and only once per cell cycle to maintain genome stability. We show here that this restriction can be bypassed through alternative transposition, a transposition reaction that utilizes the termini of two separate, nearby transposable elements (TEs). Our results suggest that alternative transposition during S phase can induce re-replication of the TEs and their flanking sequences. The DNA re-replication can spontaneously abort to generate double-strand breaks, which can be repaired to generate Composite Insertions composed of transposon termini flanking segmental duplications of various lengths. These results show how alternative transposition coupled with DNA replication and repair can significantly alter genome structure and may have contributed to rapid genome evolution in maize and possibly other eukaryotes.

Show MeSH

Related in: MedlinePlus

RET followed by homologous recombination generates identical 19,341 bpComposite Insertions in P1-rr-E17 andP1-rr-E5.(A) Structure of the chromosome 1S segment containing theprogenitor P1-ovov454 allele, prior to RET.(B) Drawing shows the RET stage corresponding to Figure 1D. Recombination between the5248 bp repeats near the two DSBs (marked by > or <) generates aComposite Insertion. (C) Structure ofP1-rr-E17 containing TDD (left-hand triangle) andComposite Insertion (right-hand triangle). All the symbols have the samemeaning as in Figure 2. Note:P1-rr-E5 contains the 19,341 bp CI but does not containthe TDD. See text for details.DOI:http://dx.doi.org/10.7554/eLife.03724.010
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4270019&req=5

fig5: RET followed by homologous recombination generates identical 19,341 bpComposite Insertions in P1-rr-E17 andP1-rr-E5.(A) Structure of the chromosome 1S segment containing theprogenitor P1-ovov454 allele, prior to RET.(B) Drawing shows the RET stage corresponding to Figure 1D. Recombination between the5248 bp repeats near the two DSBs (marked by > or <) generates aComposite Insertion. (C) Structure ofP1-rr-E17 containing TDD (left-hand triangle) andComposite Insertion (right-hand triangle). All the symbols have the samemeaning as in Figure 2. Note:P1-rr-E5 contains the 19,341 bp CI but does not containthe TDD. See text for details.DOI:http://dx.doi.org/10.7554/eLife.03724.010

Mentions: The CI in P1-rr-E17 (GenBank accession # KM013689) is 19,341 bp inlength (Figure 4); its structure suggests thatthe DSBs predicted in Figure 1D were repairedvia homologous recombination (HR) between two direct repeat sequences that flank thep1 gene in P1-ovov454 (Lechelt et al., 1989). These repeats (hatched boxes in Figure 2A) are 5248 bp in length; the proximalcopy is 4555 bp from the Ac element while the distal copy is 2934 bpfrom fAc (Figure 2A). Ifre-replication continued beyond the Ac and fAcsegments and into the flanking 5248 bp repeats before aborting, then the DSBs couldbe repaired via HR to generate the observed structures (Figure 5). The two repeat copies flankingP1-ovov454 differ at six SNPs in the distal half of the repeats(Figure 2A, red vertical short lines in thehatched box). Sequences of the P1-rr-E17 allele show that the repeatin the CI is identical to the proximal copy. These results suggest that the HRcrossover occurred between the proximal halves of the two repeats (Figure 5).10.7554/eLife.03724.010Figure 5.RET followed by homologous recombination generates identical 19,341 bpComposite Insertions in P1-rr-E17 andP1-rr-E5.


Transposition-mediated DNA re-replication in maize.

Zhang J, Zuo T, Wang D, Peterson T - Elife (2014)

RET followed by homologous recombination generates identical 19,341 bpComposite Insertions in P1-rr-E17 andP1-rr-E5.(A) Structure of the chromosome 1S segment containing theprogenitor P1-ovov454 allele, prior to RET.(B) Drawing shows the RET stage corresponding to Figure 1D. Recombination between the5248 bp repeats near the two DSBs (marked by > or <) generates aComposite Insertion. (C) Structure ofP1-rr-E17 containing TDD (left-hand triangle) andComposite Insertion (right-hand triangle). All the symbols have the samemeaning as in Figure 2. Note:P1-rr-E5 contains the 19,341 bp CI but does not containthe TDD. See text for details.DOI:http://dx.doi.org/10.7554/eLife.03724.010
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4270019&req=5

fig5: RET followed by homologous recombination generates identical 19,341 bpComposite Insertions in P1-rr-E17 andP1-rr-E5.(A) Structure of the chromosome 1S segment containing theprogenitor P1-ovov454 allele, prior to RET.(B) Drawing shows the RET stage corresponding to Figure 1D. Recombination between the5248 bp repeats near the two DSBs (marked by > or <) generates aComposite Insertion. (C) Structure ofP1-rr-E17 containing TDD (left-hand triangle) andComposite Insertion (right-hand triangle). All the symbols have the samemeaning as in Figure 2. Note:P1-rr-E5 contains the 19,341 bp CI but does not containthe TDD. See text for details.DOI:http://dx.doi.org/10.7554/eLife.03724.010
Mentions: The CI in P1-rr-E17 (GenBank accession # KM013689) is 19,341 bp inlength (Figure 4); its structure suggests thatthe DSBs predicted in Figure 1D were repairedvia homologous recombination (HR) between two direct repeat sequences that flank thep1 gene in P1-ovov454 (Lechelt et al., 1989). These repeats (hatched boxes in Figure 2A) are 5248 bp in length; the proximalcopy is 4555 bp from the Ac element while the distal copy is 2934 bpfrom fAc (Figure 2A). Ifre-replication continued beyond the Ac and fAcsegments and into the flanking 5248 bp repeats before aborting, then the DSBs couldbe repaired via HR to generate the observed structures (Figure 5). The two repeat copies flankingP1-ovov454 differ at six SNPs in the distal half of the repeats(Figure 2A, red vertical short lines in thehatched box). Sequences of the P1-rr-E17 allele show that the repeatin the CI is identical to the proximal copy. These results suggest that the HRcrossover occurred between the proximal halves of the two repeats (Figure 5).10.7554/eLife.03724.010Figure 5.RET followed by homologous recombination generates identical 19,341 bpComposite Insertions in P1-rr-E17 andP1-rr-E5.

Bottom Line: Every DNA segment in a eukaryotic genome normally replicates once and only once per cell cycle to maintain genome stability.The DNA re-replication can spontaneously abort to generate double-strand breaks, which can be repaired to generate Composite Insertions composed of transposon termini flanking segmental duplications of various lengths.These results show how alternative transposition coupled with DNA replication and repair can significantly alter genome structure and may have contributed to rapid genome evolution in maize and possibly other eukaryotes.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Development and Cell Biology, Iowa State University, Ames, United States.

ABSTRACT
Every DNA segment in a eukaryotic genome normally replicates once and only once per cell cycle to maintain genome stability. We show here that this restriction can be bypassed through alternative transposition, a transposition reaction that utilizes the termini of two separate, nearby transposable elements (TEs). Our results suggest that alternative transposition during S phase can induce re-replication of the TEs and their flanking sequences. The DNA re-replication can spontaneously abort to generate double-strand breaks, which can be repaired to generate Composite Insertions composed of transposon termini flanking segmental duplications of various lengths. These results show how alternative transposition coupled with DNA replication and repair can significantly alter genome structure and may have contributed to rapid genome evolution in maize and possibly other eukaryotes.

Show MeSH
Related in: MedlinePlus