Download Minos, a new transposable element from Drosophila hydei, is a

6646 Nucleic Acids Research, Vol. 19, No. 23
Minos, a new transposable element from Drosophila hydei,
is a member of the Tc1-like family of transposons
Gerald Franz1 + and Charalambos Savakis 12 *
institute of Molecular Biology and Biotechnology, Research Center of Crete, FO.R.T.H,
PO Box 1527, Heraklion 711 10, Crete and department of Medical Sciences, University of Crete
Medical School, Heraklion, Crete, Greece
EMBL accession no. X61695
Submitted September 23, 1991
We have cloned and sequenced a new repetitive element from
Drosophila hydei. The element was isolated in a screen of a
genomic library from D. hydei strain bbx (1), performed to
recover clones containing non-ribosomal DNA adjacent to
ribosomal DNA sequences. A sequence 1775 nucleotides long
was found inserted within the external transcribed spacer the
rDNA locus, between bases 4257 and 4258 of the published
sequence (2) (Figure 1). Southern blots of restricted DNA from
two D. hydei strains showed distinct banding patterns (Figure
1), suggesting that the element is, or has until recently been
mobile.
The element was named Minos, after the legendary king who
inhabited the palace located near our laboratories. The sequence
of Minos has the following salient features:
1. Perfect inverted repeats 255 nt long (nucleotides 1 to 255
and 1521 to 1775) are found at the ends of the element.
2. Two non-overlapping open reading frames exist on the same
strand. The first, designated ORF1, is located between nucleotides
334 and 792, begins with an ATG, and can encode a 153 amino
acid long peptide. The second, designated ORF2, is located
between nucleotides 898 and 1476 and does not begin with an
ATG. The peptide sequence encoded by ORF2 has significant
similarity with the putative transposase encoded by the long open
reading frame of the transposable element Tel of Caenorhabditis
elegans (3). Of the 201 amino acid residues in the two aligned
sequences, 64 (~ 32%) are identical and 95 (—47%) are related
(Figure 2). Similar sequence homology was detected between
ORF2 and regions of the other members of the Tel-like
transposon family (4, 5, 6, 7).
Based on the genomic distribution of the element, the presence
of perfect terminal repeats, and the sequence similarity with Tel,
we conclude that Minos is a newly discovered member of the
widely dispersed class of Tel-like transposons. The sequenced
element, because of the stop codon within the putative transposase
gene, presumably cannot encode active transposase.
REFERENCES
1. Franz.G., Kunz.W. and Grimm.Ch. (1983) Molec. Gen. Genet. 191, 74-80.
2. Tautz.D., Tautz.C, Webb,D. and Dover.G.A. (1987) J. Mol. Biol. 195,
525-542.
3. Rosenzweig,B., Liao,L.W. and Hirsh.D. (1983) Nucleic Acids Res. 11,
4201-4209.
4. Harris.L.J., Baillie.D.L and Rose.A.M. (1988) Nucleic Acids Res. 16.
5991-5997.
5. Harris.L.J., Prasad,S. and Rose.A.M. (1990)7. Mol. Evol. 30, 359-369.
6. Brierley.H L. and Potter.S.S. (1985) Nucleic Acids Res. 13, 485-500.
7. Brezinksy.L., Wang.G.V.L, Humphreys.T. and Hunt.J. (1990) Nucleic Acids
Res. 18, 2053-2059.
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Figure 1. Minos sequences in the D. hydei genome. Top: Position of the cloned
element within the rDNA repeat unit. Vertical arrows indicate the positions of
£coRI (E) and Hindlll (H) sites; the horizontal arrow indicates the rDNA
transcriptional start. The hatched box represents the HindUl-EcoRl fragment used
for hybridization. Bottom: DNA from bb1 strain (lane A) and a wild-type strain
(lane B) was digested with EcoRI, subjected to electrophoresis, blotted and
hybridized with the Hindlll-EcoRl Minos DNA probe. The origin of
electrophoresis is on the left.
3 LRCftQEIA
ACKNOWLEDGEMENTS
This work was supported by European Community
Mediterranean Integrated Pregrain funds to the IMBB and by a
European Community training fellowship to G.F.
Figure 2. Alignment of Minos and Tel hypothetical peptides. Solid boxes between
the sequences indicate identities and stippled boxes indicate conservative
replacements. The Minos sequence begins with the first in-frame methionine
upstream of the termination codon.
* To whom correspondence should be addressed
+
Present address: Entomology Unit, IAEA Laboratories, A-244 Seibersdorf, Austria