A novel class of Helitron-related transposable elements in maize contain portions of multiple pseudogenes.
We recently described a maize mutant caused by an insertion of a Helitron type transposable element (Lal, S.K., Giroux, M.J., Brendel, V., Vallejos, E. and Hannah, L.C., 2003, Plant Cell, 15: 381-391). Here we describe another Helitron insertion in the barren stalk1 gene of maize. The termini of a 6525 bp insertion in the proximal promoter region of the mutant reference allele of maize barren stalk1 gene (ba1-ref) shares striking similarity to the Helitron insertion we reported in the Shrunken-2 gene. This insertion is embedded with pseudogenes that differ from the pseudogenes discovered in the mutant Shrunken-2 insertion. Using the common terminal ends of the mutant insertions as a query, we discovered other Helitron insertions in maize BAC clones. Based on the comparison of the insertion site and PCR amplified genomic sequences, these elements inserted between AT dinucleotides. These putative non-autonomous Helitron insertions completely lacked sequences similar to RPA (replication protein A) and DNA Helicases reported in other species. A blastn analysis indicated that both the 5' and 3' termini of Helitrons are repeated in the maize genome. These data provide strong evidence that Helitron type transposable elements are active and may have played an essential role in the evolution and expansion of the maize genome.
Gupta
Smriti
S
Department of Biological Sciences, Oakland University, Rochester, MI 48309-4401, USA.
Gallavotti
Andrea
A
Stryker
Gabrielle A
GA
Schmidt
Robert J
RJ
Lal
Shailesh K
SK
D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000235:genetics; D004251:DNA Transposable Elements / Q000235:genetics*; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D018745:Genome, Plant; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D016254:Mutagenesis, Insertional; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics; D011544:Pseudogenes / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D003313:Zea mays / Q000235:genetics*; D015028:Zein / Q000235:genetics
D004251:DNA Transposable Elements; D018744:DNA, Plant; D010940:Plant Proteins; C113020:ZmCip1 protein, Zea mays; D015028:Zein; D004265:DNA Helicases