The Suppressor‐mutator element and the evolutionary riddle of transposons

Fedoroff, Nina V.

doi:10.1046/j.1365-2443.1999.00233.x

Cited by 31 publications

(15 citation statements)

References 88 publications

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“…Transposable elements are widespread constituents of all eukaryotic genomes (52). Epigenetic processes, particularly DNA methylation, have been implicated in regulating the activity of plant transposable elements (53). In Arabidopsis, Robertson's Mutator transposons and members of the CACTA superfamily are controlled by the SWI2͞ SNF2 chromatin-remodeling gene DDM1 (28,29).…”

Section: Discussionmentioning

confidence: 99%

Suppressors of transcriptional transgenic silencing in Chlamydomonas are sensitive to DNA-damaging agents and reactivate transposable elements

Jeong

Wu-Scharf

Zhang

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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In the unicellular green alga Chlamydomonas reinhardtii, the epigenetic silencing of transgenes occurs, as in land plants, at both the transcriptional and posttranscriptional levels. In the case of singlecopy transgenes, transcriptional silencing takes place without detectable cytosine methylation of the introduced DNA. We have isolated two mutant strains, Mut-9 and Mut-11, that reactivate expression of a transcriptionally silenced single-copy transgene. These suppressors are deficient in the repression of a DNA transposon and a retrotransposon-like element. In addition, the mutants show enhanced sensitivity to DNA-damaging agents, particularly radiomimetic chemicals inducing DNA double-strand breaks. All of these phenotypes are much more prominent in a double mutant strain. These observations suggest that multiple partly redundant epigenetic mechanisms are involved in the repression of transgenes and transposons in eukaryotes, presumably as components of a system that evolved to preserve genomic stability. Our results also raise the possibility of mechanistic connections between epigenetic transcriptional silencing and DNA double-strand break repair.

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Section: Discussionmentioning

confidence: 99%

Suppressors of transcriptional transgenic silencing in Chlamydomonas are sensitive to DNA-damaging agents and reactivate transposable elements

Jeong

Wu-Scharf

Zhang

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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“…[19] demonstrated that the maize En/Spm-I/dSpm two-component system can transpose in rice. En/Spm transposons are known to be linked with genes and their expression; transposition is controlled by interacting autoregulatory and/or epigenetic mechanisms and is, therefore, relatively independent of their chromosomal localization [20]. Each En/Spm transposon possesses a gene encoding a TPase that has several conserved domains, and it is technically possible to locate the chromosomal positions of these elements by fluorescent in situ hybridization (FISH) of TPase fragments amplified from the genomic DNA of the species [8].…”

Section: Introductionmentioning

confidence: 99%

En/Spm-like transposons in Poaceae species: Transposase sequence variability and chromosomal distribution

Altinkut

Raskina

Nevo

2006

Cellular and Molecular Biology Letters

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Abstract:Belonging to Class II of transposable elements, En/Spm transposons are widespread in a variety of distantly related plant species. Here, we report on the sequence conservation of the transposase region from sequence analyses of En/Spm-like transposons from Poaceae species, namely Zingeria biebersteiniana, Zingeria trichopoda, Triticum monococcum, Triticum urartu, Hordeum spontaneum, and Aegilops speltoides. The transposase region of En/Spm-like transposons was cloned, sequenced, and compared with equivalent regions of Oryza and Arabidopsis from the gene bank database. Southern blot analysis indicated that the En/Spm transposon was present in low (Hordeum spontaneum, Triticum monococcum, Triticum urartu) through medium (Zingeria bieberstiana, Zingeria trichopoda) to relatively high (Aegilops speltoides) copy numbers in Poaceae species. A cytogenetic analysis of the chromosomal distribution of En/Spm transposons revealed the concurence of the chromosomal localization of the En/Spm clusters with mobile clusters of rDNA. An analysis of En/Spm-like transposase amino acid sequences was carried out to investigate sequence divergence between 5 genera -Triticum, Aegilops, Zingeria, Oryza and Arabidopsis. A distance matrix was generated; apparently, En/Spm-like transposase sequences shared the highest sequence homology intra-generically and, as expected, these sequences were significantly diverged from those of Unauthenticated Download Date | 5/10/18 9:16 AM CELLULAR & MOLECULAR BIOLOGY LETTERS 215O. sativa and A. thaliana. A sequence comparison of En/Spm-like transposase coding regions defined that the intra-genomic complex of En/Spm-like transposons could be viewed as relatively independent, vertically transmitted, and permanently active systems inside higher plant genomes.

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“…Discovered first in maize, transposons and retrotransposons occupy 50%-80% of this genome and frequently reach copy numbers of several thousand (SanMiguel et al 1998;Fedoroff 1999). Most DNA transposons are no longer active and require an autonomous element in trans to transpose.…”

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confidence: 99%

“…In maize, cisacting transposon regulatory mechanisms are thought to include DNA methylation. Transposase promoter sequences from McClintock's Activator and SuppressorMutator transposons, for example, are hypomethylated in the active state, although the rest of the element is methylated constitutively (Banks et al 1988;Fedoroff 1999). In vitro, transposon DNA binds more efficiently to transposase when hemimethylated than when unmethylated or fully methylated, possibly because this marks recently replicated transposons in vivo (Kunze and Starlinger 1989).…”

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confidence: 99%

Robertson's Mutator transposons in A. thaliana are regulated by the chromatin-remodeling gene Decrease in DNA Methylation (DDM1)

Singer¹,

Yordan²,

Martienssen³

2001

Genes Dev.

294

229

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Robertson's Mutator transposable elements in maize undergo cycles of activity and then inactivity that correlate with changes in cytosine methylation. Mutator-like elements are present in the Arabidopsis genome but are heavily methylated and inactive. These elements become demethylated and active in the chromatin-remodeling mutant ddm1 (Decrease in DNA Methylation), which leads to loss of heterochromatic DNA methylation. Thus, DNA transposons in plants appear to be regulated by chromatin remodeling. In inbred ddm1 strains, transposed elements may account, in part, for mutant phenotypes unlinked to ddm1. Gene silencing and paramutation are also regulated by DDM1, providing support for the proposition that epigenetic silencing is related to transposon regulation.

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The Suppressor‐mutator element and the evolutionary riddle of transposons

Cited by 31 publications

References 88 publications

Suppressors of transcriptional transgenic silencing in Chlamydomonas are sensitive to DNA-damaging agents and reactivate transposable elements

Suppressors of transcriptional transgenic silencing in Chlamydomonas are sensitive to DNA-damaging agents and reactivate transposable elements

En/Spm-like transposons in Poaceae species: Transposase sequence variability and chromosomal distribution

Robertson's Mutator transposons in A. thaliana are regulated by the chromatin-remodeling gene Decrease in DNA Methylation (DDM1)

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