General Properties of Mobile Dispersed Genetic Elements in Drosophila melanogaster

Tchurikov, Nickolai A.; Ilyin, Yu. V.; Skryabin, K. G.; Ananiev, E. V.; Bayev, A.A.; Krayev, A.S.; Zelentsova, E. S.; Kulguskin, V.V.; Lyubomirskaya, N. V.; Georgiev, G P

doi:10.1101/sqb.1981.045.01.083

Cited by 65 publications

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“…1). Since a putative polyadenylation signal AATAAA is located 70 and 50 nucleotides downstream of RNA starts 1 and 2, respectively, it may be suggested that, as with retroviruses [31] and copia [17], 412 has an LTR consisting of U3, R and U5 (U5= [17,191;8,Ty [36]. Essential parts of amino acid sequence alignment between Mo-MuLV and 17.6 have been described [18].…”

Section: Resultsmentioning

confidence: 99%

Nucleotide sequence characterization of a Drosophila retrotransposon, 412

et al. 1986

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The nucleotide sequence of the internal region of a Drosophila retrotransposon. 412, was determined. The genome of 412 was found to consist of two long open-reading frames (ORFs 1 and 2), an unusually long putative leader region and long terminal repeats (LTRs). As with 17.6, 297 and gypsy, ORFs 1 and 2 slightly overlap each other and are out of phase by + 2 . ORF2 includes the nucleotide sequences coding for the putative protease, reverse transcriptase and integrase, and is similar in entire organization to the pol gene of Moloney murine leukaemia virus. In spite of the difference in insertion specificity, integrase, an enzyme presumably responsible for insertion, was found to be similar in amino acid sequence to the counterparts of 17.6, 297 and gypsy. There is no ORF in 412 which corresponds to retroviral env or ORF3s of 17.6 and 297. Analysis of 412 transcripts suggested that 412 LTR is composed of U3, R and U5. The gene for a potential primer tRNA for putative reverse transcription of 412 was also surveyed and the 3'-terminal 15 nucleotides of a putative arginine tRNA were found to be exactly complementary to the putative primer-binding site of 412.Drosophila copia-like elements or retrotransposons are formed from the largest group of transposable genetic elements in Drosophila melanogaster. They are intimately related in evolution to retroviral proviruses in vertebrates In our previous experiments the complete nucleotide sequences of three Drosophila retrotransposons 17.6 [15], 297 [16] and copia [17] were determined. 17.6 and 297 contained three open reading frames (ORFs) similar in size and location to retroviral gag, pol and env. The second ORFs of these two elements were further shown each to include the nucleotide sequence coding for a reverse-transcriptase-like enzyme and be, in all respects of their organization, very similar to the pol gene of Moloney murine leukaemia virus (Mo-MuLV) [15,16, 181. In contrast, the genome of copia contained a single long ORF [17, 191 including genes for the major capsid protein of copia-related virus-like particles and reverse-transcriptase-like enzyme much less similar to the reverse transcriptase of MoMuLV [17,19]. These results suggest the genome organization in Drosophila retrotransposons to be very much diversified.To confirm and determine the further implications of this notion, a determination was made of the complete nucleotide sequence of another Drosophila retrotransposon, 412, having terminal dinucleotides identical to those of copia and retrovirus proviruses but different from those of 17.6, 297 and gypsy [4, 15-17, 20, 211. The genome of 412 was found to contain two long ORFs (ORFs 1 and 2) and an unusually long putative leader region with two short ORFs. As with 17.6 [15], 297 [16] and gypsy (unpublished), ORFs 3 and 2 slightly overlap each other and are out of phase by t 2 . The entire structure of ORF2 is of the 17.6 type and the putative integrase encoded by a portion of ORF2 is similar in amino acid sequence to the counterparts of 17.6, 297 and gy...

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Section: Resultsmentioning

confidence: 99%

Nucleotide sequence characterization of a Drosophila retrotransposon, 412

et al. 1986

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“…An inbred stock of the Oregon strain in which the localization of mdg elements remains invariable is another example. The transposition rate ofmdgis below 10-4-10-5 [7,8] whereas that ofFBelements is somewhat higher (up to…”

Section: Transpositions Of Mobile Elements Are Very Rare Events But mentioning

confidence: 91%

Mobile genetic elements in animal cells and their biological significance

Georgiev¹

1984

European Journal of Biochemistry

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(Plenary lecture at the 16th FEBS Meeting in Moscow, June 30,1984) -EJB 84 0753 Mobile genetic elements were discovered by McClintock while analysing unstable mutations in maize. The structural and functional studies of such elements became possible after their cloning, first from the genome of Drosophilu melanoguster. In particular, Ilyin et al. demonstrated the varying location of the described elements in D. melunoguster chromosomes, thus providing the first evidence of their mobility. Mobile elements comprise a significant part of the genetic material in D. melunoguster (not less than 10%). Several classes of mobile elements do exist. Mobile dispersed genetic elements (mdg elements) are among the best characterized ones. Mdg elements are represented in the genome by dozens of families, each consisting of 10-150 copies. They are very similar structurally to proviruses of endogenous retroviruses. In particular, the both contain long terminal repeats (LTRs). The nucleotide sequences of LTRs and their flanking sequences of several mdg elements were determined. Their analysis suggested that RNA reverse transcription should be involved in the mdg amplification. It has been found that putative transposition intermediates, i.e. extrachromosomal DNA copies of mdg elements, are synthesized by reverse transcriptase in D. melanogaster culture cells. Another type of mobile genes is represented by P factor and similar elements. P factor seems to encode 'transposase' participating in direct excision and insertion of P elements themselves as well as of other mobile genes (mdg and fold-back elements). Besides these 'active transposons' which encode the enzyme machinery for transposition, a number of other sequences which may be transposed are present in the genome. RNAs synthesized on such elements can serve as a template for reverse transcriptase, and the DNA formed can then be inserted at new sites of the genome. Among such sequences are the so-called short ubiquitous repeats: B1 and B2 in mouse genome and Alu in human genome. We found that, at least in several cases, B-type sequences were located at the 3' end of mRNA. Short repetitive sequences were also detected at the 3' end of certain mRNAs of D. melunoguster. Usually the transpositions of mobile genes occur very rarely. However, under certain conditions, for example, in hybrid dysgenesis, they become more frequent.

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“…Previous studies show that Drosophila tissue culture cells have amplified Tn content (Potter et al 1979;Tchurikov et al 1981;Maisonhaute et al 2007;Wen et al 2014) and hypothesize that this amplification is necessary for creating immortal cell lines (Junakovic et al 1988). Once established, Tn location and number appear stable in Drosophila Kc and S2 cell lines (Junakovic et al 1988).…”

Section: Production Of Dsrnas By Convergent Transcription Is a Novel mentioning

confidence: 99%

Antisense Transcription of Retrotransposons in Drosophila: An Origin of Endogenous Small Interfering RNA Precursors

2015

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Movement of transposons causes insertions, deletions, and chromosomal rearrangements potentially leading to premature lethality in Drosophila melanogaster. To repress these elements and combat genomic instability, eukaryotes have evolved several small RNA-mediated defense mechanisms. Specifically, in Drosophila somatic cells, endogenous small interfering (esi)RNAs suppress retrotransposon mobility. EsiRNAs are produced by Dicer-2 processing of double-stranded RNA precursors, yet the origins of these precursors are unknown. We show that most transposon families are transcribed in both the sense (S) and antisense (AS) direction in Dmel-2 cells. LTR retrotransposons Dm297, mdg1, and blood, and non-LTR retrotransposons juan and jockey transcripts, are generated from intraelement transcription start sites with canonical RNA polymerase II promoters. We also determined that retrotransposon antisense transcripts are less polyadenylated than sense. RNA-seq and small RNA-seq revealed that Dicer-2 RNA interference (RNAi) depletion causes a decrease in the number of esiRNAs mapping to retrotransposons and an increase in expression of both S and AS retrotransposon transcripts. These data support a model in which double-stranded RNA precursors are derived from convergent transcription and processed by Dicer-2 into esiRNAs that silence both sense and antisense retrotransposon transcripts. Reduction of sense retrotransposon transcripts potentially lowers element-specific protein levels to prevent transposition. This mechanism preserves genomic integrity and is especially important for Drosophila fitness because mobile genetic elements are highly active.

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General Properties of Mobile Dispersed Genetic Elements in Drosophila melanogaster

Cited by 65 publications

References 0 publications

Nucleotide sequence characterization of a Drosophila retrotransposon, 412

Nucleotide sequence characterization of a Drosophila retrotransposon, 412

Mobile genetic elements in animal cells and their biological significance

Antisense Transcription of Retrotransposons in Drosophila: An Origin of Endogenous Small Interfering RNA Precursors

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