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The MT family of mouse DNA is made of short interspersed repeated elements
1Département de Microbiologie, Faculté de Médecine, Université de Sherbrooke, Québec, Canada.
Abstract:
In certain mouse cells transformed by polyomavirus (Py), viral DNA is excised from the chromosome together with a defined mouse component, which has been designated Ins [Bourgaux et al., Virology 122 (1982) 84-97]. Ins carries a sequence which anneals with the DNA at many sites in the mouse genome, while displaying no detectable homology with well-characterized SINEs and LINEs [Sylla et al., Gene 29 (1984) 343-350]. Recently, others have reported that this sequence belongs to a newly discovered family of repetitive mouse DNA, designated MT for Mouse Transcript [Heinlein et al., Nucl. Acids Res. 14 (1986) 6403-6416]. We demonstrate here that the MT family consists of short interspersed repetitive sequences (SINEs) with structural features of retroposons. Using cloned fragments of Ins as probes, we have identified recombinants carrying MT sequences in a genomic library of mouse DNA. Regions of homology to the probes were subcloned twice from the DNA of lambda phage using plasmids pAT153 and pUC13, and characterized in detail by heteroduplex mapping and by sequencing. The three distinct elements thus studied were highly homologous over 400 bp, terminated in 3' with a short sequence rich in A residues, and were flanked by a short direct repeat. On the basis of these complete elements, a 400-bp consensus sequence was established for the MT family.
Insights
The Mouse Transcript (MT) family comprises short interspersed repetitive sequences (SINEs) with retroposon characteristics. These elements are found interspersed throughout the mouse genome and share structural features.
Area of Science:
- Molecular Biology
- Genetics
- Genomics
Background:
- Polyomavirus (Py) transformation in mouse cells leads to the excision of viral DNA along with a mouse component named Ins.
- The Ins sequence anneals to multiple sites in the mouse genome but lacks homology with known SINEs and LINEs.
- A newly identified family of repetitive mouse DNA, designated Mouse Transcript (MT), has been reported.
Purpose of the Study:
- To characterize the newly discovered Mouse Transcript (MT) family of repetitive mouse DNA.
- To determine if the MT family consists of short interspersed repetitive sequences (SINEs) and possesses retroposon features.
Main Methods:
- Utilized cloned fragments of Ins as probes to screen a mouse genomic DNA library.
- Identified and isolated recombinants containing MT sequences using lambda phage DNA.
- Subcloned homologous regions using plasmids pAT153 and pUC13 for detailed characterization.
- Employed heteroduplex mapping and DNA sequencing for structural and sequence analysis.
Main Results:
- Demonstrated that the MT family consists of short interspersed repetitive sequences (SINEs) with structural characteristics of retroposons.
- Characterized three distinct MT elements, showing high homology over 400 bp.
- Observed 3' adenine-rich sequences and flanking short direct repeats in the studied MT elements.
- Established a 400-bp consensus sequence for the MT family based on the analyzed elements.
Conclusions:
- The Mouse Transcript (MT) family represents a novel class of SINEs within the mouse genome.
- MT elements exhibit structural features consistent with retroposons, suggesting a mechanism of propagation.
- The characterized consensus sequence provides a foundation for further investigation into the function and distribution of MT elements.