Identification of the coding sequence for a reverse transcriptase-like enzyme in a transposable genetic element in Drosophila melanogaster

Saigo, Kaoru; Kugimiya, Wataru; Matsuo, Yohtaro; Inouye, Satoshi; Yoshioka, Katsuji; Yuki, Shunji

doi:10.1038/312659a0

Cited by 212 publications

(119 citation statements)

References 27 publications

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“…8). The 18-nucleotide sequence is identical to the primer binding site of element 297, which is in turn complementary to the 3' end of Drosophila tRNASer (38). Unlike the retroproviral primer binding site which lies immediately adjacent to the 5' LTR, the putative primer binding sites of TED, 297, 17.6, and gypsy overlap the LTR by one nucleotide (Fig.…”

Section: Effectsmentioning

confidence: 99%

“…A major question posed by the observed bidirectional transcription of the solo TED LTR is whether the same (23,38) and copia (9,29), the S. cerevisiae retrotransposon Ty912 (5,8), and the retrovirus human Tlymphotropic virus type III/lymphadenopathy virus (30,39,42,48). …”

Section: Effectsmentioning

confidence: 99%

“…TED also contains a purine-rich region immediately adjacent to the rightmost LTR (data not shown) which may act to initiate second-strand DNA synthesis. Morever, a full-length RNA (7 kb) (19), 17.6 (38), and gypsy bx3 (13) (which is identical to mdg4 [2]) and copia (9,29) (Fig. 5).…”

Section: Effectsmentioning

confidence: 99%

“…The LTRs carry signals necessary for initiation and termination of transcription. The transcribed internal portion of these elements contains several retroviruslike genes, including a gene (pol) with homology to reverse transcriptase (5,9,29,38). In the case of Ty, the full-length RNA extending, from LTR to LTR is copied into DNA by a process identical to that of the retroviruses, suggesting that transposition occurs through reverse transcription of an RNA intermediate (3).…”

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confidence: 99%

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Bidirectional transcription from a solo long terminal repeat of the retrotransposon TED: symmetrical RNA start sites.

Friesen¹,

Rice²,

Miller³

et al. 1986

Mol. Cell. Biol.

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A single copy of the retrotransposon TED was found integrated within the DNA genome of the insect baculovirus, Autographa californica nuclear polyhedrosis virus. After excision of the element from the viral genome, a single long terminal repeat (LTR) remained behind. We have examined the effect of this solo TED LTR on the local pattern of viral transcription. Most prominent was the transcription of two sets of abundant RNAs; both originated within the LTR but extended in opposite directions into flanking viral genes. By promoting symmetric transcription of adjacent genes, the solo LTR has the capacity to activate or repress gene expression in two directions. Primer extension analysis demonstrated that the divergent LTR transcripts were initiated near the same point within a 22-base-pair sequence having hyphenated twofold symmetry. Analogous symmetries at the initiation sites of other retrotransposon LTRs, including copia and Ty, suggested that these sequences serve to establish the precise start for transcription.The retrotransposons represent a group of eucaryotic transposable elements which bear a striking resemblance to the retroviral proviruses (for review, see reference 1). These elements, which include copia and copia-related transposons of Drosophila melanogaster and Ty of Saccharomyces cerevisiae, are flanked at both ends by long terminal repeats (LTRs). The LTRs carry signals necessary for initiation and termination of transcription. The transcribed internal portion of these elements contains several retroviruslike genes, including a gene (pol) with homology to reverse transcriptase (5, 9, 29, 38). In the case of Ty, the full-length RNA extending, from LTR to LTR is copied into DNA by a process identical to that of the retroviruses, suggesting that transposition occurs through reverse transcription of an RNA intermediate (3).By virtue of their ability to integrate randomly into the host genome and alter expression of nearby genes, the retroviruses represent an important class of insertion mutagens (for review, see reference 44). Similarly, the retrotransposons cause insertion mutations in D. melanogaster and S. cerevisiae (reviews in references 35 and 37). Integration within regulatory regions or introns of various genes has resulted in enhancement or inhibition of expression. These alterations occur at the level of transcription and are presumably due to insertion of new promoters, termination signals, or both, located within the retrotransposon. The mutagenic effects of inserted copia, gypsy, and Ty elements are suppressed by additional mutations at unlinked loci which restore transcription of the affected genes to wild-type levels (25,32,51). Mutation of the S. cerevisiae SPT3 (suppressor of Ty) gene, for instance, abolishes normal Ty transcription, which suggests that the mutational effect of certain Ty insertions is due to transcription originating from the element (51). The exact mechanisms involved are still unclear.TED is the first copia-related transposable element iden-

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Section: Effectsmentioning

confidence: 99%

Section: Effectsmentioning

confidence: 99%

Section: Effectsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Bidirectional transcription from a solo long terminal repeat of the retrotransposon TED: symmetrical RNA start sites.

Friesen¹,

Rice²,

Miller³

et al. 1986

Mol. Cell. Biol.

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“…This class includes Drosophila copia and Saccharomyces Ty elements. Sequence analysis of eopia and a related element showed that they contain open reading frames with homology to gag, pol and env genes (Saigo et al, 1984;Mount & Rubin, 1985). Furthermore, retrovirus-like particles had previously been found in copia-bearing cells (Shiba & Saigo, 1983).…”

Section: Retroviruses and Retrotransposonsmentioning

confidence: 99%

Some Highlights of Animal Virus Research in 1985

McGeoch¹,

Halliburton²,

Meulen³

et al. 1986

Journal of General Virology

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For some time, the Editors of The Journal of General Virology have sought a format for presenting accounts of advances and notable events in virology, in a broader and more flexible manner than is afforded by the traditional review of a topic in depth. This article represents an experiment in such presentation. Its aim is to look at advances in virus research, and to present brief accounts of the most important and interesting work published within a calendar year. Subject to evaluation of the success of this first essay, an annual feature is envisaged.Implementation of these fine notions, however, has demanded some compromises. Virology comprises such an awesome range of techniques and objectives, with such a disparate assembly of virus types, that rigorous limits were necessary. Thus, we have confined our attention to animal viruses, and explicitly avoided any pretension to constructing a systematic review of all virology; the idea of selectivity was pre-eminent. In addition, this initial account has been very largely composed by one author, and so reflects one particular set of interests. Molecular and genome structural aspects are emphasized, and little overt attention is paid, for instance, to immunity and pathogenesis. The true high points of published research are relatively easy to identify, and their perception is probably not much affected by personal interests. The choice of lesser topics, however, is increasingly subjective; in particular, defining a cut-off point was not trivial. Our dealings are with 1985 as far as is practicable, but research advances do not really respect such clean divisions and so some flexibility has been exercised.Our final qualification concerns the nature of scientific advance: a 'highlight' is a phenomenon of a surface, and thus can exist only with an underlying structure. In our analogy, most research papers are considered part of this substratum. They also are an essential part (indeed, the major part) of overall advance, but their existence is only implicit in the present account.For this review, we consider that the major highlights of 1985 were analysis of the structures of two picornaviruses and research on the acquired immune deficiency syndrome (AIDS), and these are presented first. We then describe in succession selected aspects of work on genome organization, virus gene expression, genome replication and virus proteins, and finish with two topics at the edge of virology, namely, work on scrapie and on retrotransposons. The structures of two picornavirusesThe single and definitive high point of animal virus research in 1985 was the publication of two papers on X-ray crystallographic determination of the three-dimensional (3D) virion 0000-7094 © 1986 SGM

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The yeast Ty element: Recent advances in the study of a model retro‐element

Adams

Kingsman

1987

BioEssays

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SummaryThe past three years have seen a dramatic increase in our understanding of the structural organization and expression strategies of the dispersed, repetitive yeast transposon, Ty. These studies have led to a logical comparison of Ty with retroviral proviruses and other mobile, repetitive elements. Such comparisons have culminated in the hypotheses that transposition occurs via the formation of Ty-encoded virus-like particles and that these particles represent a basic unit of all 'retro-systems'.

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Identification of the coding sequence for a reverse transcriptase-like enzyme in a transposable genetic element in Drosophila melanogaster

Cited by 212 publications

References 27 publications

Bidirectional transcription from a solo long terminal repeat of the retrotransposon TED: symmetrical RNA start sites.

Bidirectional transcription from a solo long terminal repeat of the retrotransposon TED: symmetrical RNA start sites.

Some Highlights of Animal Virus Research in 1985

The yeast Ty element: Recent advances in the study of a model retro‐element

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