October 2012, 12:192,
Open Access This content is freely available online to anyone, anywhere at any time.
Date: 16 Oct 2012
The SLEEPER genes: a transposase-derived angiosperm-specific gene family
DAYSLEEPER encodes a domesticated transposase from the hAT-superfamily, which is essential for development in Arabidopsis thaliana. Little is known about the presence of DAYSLEEPER orthologs in other species, or how and when it was domesticated. We studied the presence of DAYSLEEPER orthologs in plants and propose a model for the domestication of the ancestral DAYSLEEPER gene in angiosperms.
Using specific BLAST searches in genomic and EST libraries, we found that DAYSLEEPER-like genes (hereafter called SLEEPER genes) are unique to angiosperms. Basal angiosperms as well as grasses (Poaceae) and dicotyledonous plants possess such putative orthologous genes, but SLEEPER-family genes were not found in gymnosperms, mosses and algae. Most species contain more than one SLEEPER gene. All SLEEPERs contain a C2H2 type BED-zinc finger domain and a hATC dimerization domain. We designated 3 motifs, partly overlapping the BED-zinc finger and dimerization domain, which are hallmark features in the SLEEPER family. Although SLEEPER genes are structurally conserved between species, constructs with SLEEPER genes from grapevine and rice did not complement the daysleeper phenotype in Arabidopsis, when expressed under control of the DAYSLEEPER promoter. However these constructs did cause a dominant phenotype when expressed in Arabidopsis. Rice plant lines with an insertion in the RICESLEEPER1 or 2 locus displayed phenotypic abnormalities, indicating that these genes are functional and important for normal development in rice. We suggest a model in which we hypothesize that an ancestral hAT transposase was retrocopied and stably integrated in the genome during early angiosperm evolution. Evidence is also presented for more recent retroposition events of SLEEPER genes, such as an event in the rice genome, which gave rise to the RICESLEEPER1 and 2 genes.
We propose the ancestral SLEEPER gene was formed after a process of retro-transposition during the evolution of the first angiosperms. It may have acquired an important function early on, as mutation of two SLEEPER genes in rice, like the daysleeper mutant in A. thaliana gave a developmental phenotype indicative of their importance for normal plant development.
Rubin E, Lithwick G, Levy AA: Structure and evolution of the hAT transposon superfamily. Genetics 2001, 158:949–957.PubMed
Thompson JD, Gibson TJ, Higgins DG: Multiple sequence alignment using ClustalW and ClustalX. Curr Protoc Bioinformatics 2002, Chapter 2:Unit 2.
den Dulk-Ras A, Hooykaas PJ: Electroporation of agrobacterium tumefaciens. Methods Mol Biol 1995, 55:63–72.PubMed
Siltberg J, Liberles DA: A simple covarion-based approach to analyse nucleotide substitution rates. J Evol Biol 2002, 15:588–594.CrossRef
Vaknin K, Goren A, Ast G: TEs or not TEs? That is the evolutionary question. J Biol 2009, 8:83.
- The SLEEPER genes: a transposase-derived angiosperm-specific gene family
- Open Access
- Available under Open Access This content is freely available online to anyone, anywhere at any time.
BMC Plant Biology
- Online Date
- October 2012
- Online ISSN
- BioMed Central
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