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General Information
Symbol
HeT-A
Species
D. melanogaster
Feature type
FlyBase ID
FBte0000143
Sequences and Components
Sequence Ontology (SO)
Insertions and Copy Number
Copy number and comments

3 in euchromatin of Release 3 genome annotation, of which zero are full length.

Target Site Duplication
Size (bp)
Orthologs
Curated drosophilid orthologs
Comments

HeT-A and TART-element, previously considered to be closely related, have very different transcriptional characteristics. Additionally, features of TART-element sequence organisation resemble those of a subclass of non-LTR elements characterized by unequal terminal repeats. The distinctive transcription patterns of HeT-A and TART-element are conserved in D.yakuba.

HeT-A sequences have been found in the centric heterochromatin of chromosome 3.

The HeT-A promoter is at the 3' end of the element and directs transcription of the HeT-A element immediately downstream in the tandem array in which they are found. The HeT-A element appears to be an evolutionary intermediate between LTR and non-LTR retrotransposons. Considering two HeT-A elements in tandem array, the promoter-containing 3' end of the upstream element is identical to the promoter-containing 3' end of the downstream element, and this "extended element" is structurally and functionally equivalent to an LTR retrotransposon. The promoter-containing 3' end of the upstream element acts as a surrogate for the 5' LTR characteristic of the LTR retrotransposon, although it is actually part of the flanking element. The HeT-A element does not encode its own reverse transcriptase.

Comparison of integrase/transposase domains to new elements containing the DDE signature.

HeT-A promoter activity is located in the 3' end of the element. In HeT-A arrays the 3' sequence of one element directs transcription of its downstream neighbour.

HeT-A retrotransposons hybridise close to the centromere of the Y chromosome.

HeT-A element and TART-element may be evolutionarily related to telomerase, in both cases an enzyme extends the end of a chromosome by adding DNA copied from an RNA template.

A HeT-A element has been cloned and sequenced. The unit length of the HeT-A element is approximately 6kb.

The HeT-A element is approximately 6kb in length. It can be divided into three regions; a protein coding region composed of two overlapping reading frames, a 5' non-coding region and a 3' non-coding region (which makes up approximately half the HeT-A element).

Analysis of HeT-A transcripts suggests that HeT-A elements transposase by means of a polyadenylated RNA intermediate and that each element joins to the chromosome end by means of the poly(A) tail of the RNA.

The genomic organization (oligo(A) tails facing proximally at chromosome ends) and sequence analysis of 29 different HeT-A fragments supports the model of telomere elongation by transposition of HeT-A elements.

HeT-A sequences are never found in the euchromatin. Y associated HeT-A clusters have significantly different structures than telomeric clusters, and may arise by different transposition mechanisms.

A transposon family of non-long terminal repeat retrotransposons found at the telomere. HeT-A elements transpose to broken chromosome ends. Evidence suggests that they can also transpose to natural chromosome ends.

Transposition of HeT-A onto broken chromosome ends is implicated in chromosome healing. Ends of X chromosomes with new HeT-A additions receded at the same rate as broken ends before HeT-A elements attached. Approximately 1% of chromosomes per generation aquired new HeT-A sequences of an average of 6kb at their ends, and the rate of addition of new material per generation matches the observed rate of loss caused by incomplete replication at the ends of the DNA molecule. Transposition of HeT-A onto broken chromosome ends is implicated in chromosome healing. Ends of X chromosomes with new HeT-A additions receded at the same rate as broken ends before HeT-A elements attached. Approximately 1% of chromosomes per generation aquired new HeT-A sequences of an average of 6kb at their ends, and the rate of addition of new material per generation matches the observed rate of loss caused by incomplete replication at the ends of the DNA molecule.

HeT-A is a transposable element that heals broken chromosomes: it may have a structural role in telomere organization or maintenance.

HeT-As is transcribed and are conserved in the D.melanogaster species subgroup. It may play a role in the structure and/or function of telomeres.

Sequence of a HeT-A element includes two overlapping open reading frames that are one nucleotide out of frame with respect to each other. The longer ORF contains Cys-His motifs strongly resembling nucleic acid binding domains of gag-like proteins and the overall organisation is reminiscent of LINE elements.

construct_comment: Associated with telomeres.

The distribution of different subfragments of HeT-A DNA throughout the genome has been studied.

HeT-A may have a role in organizing or maintaining the ends of chromosomes. The association of HeT-A with the newly acquired telomeres, in a formerly euchromatic region of C(1)A, strengthens this correlation.

Other Information
Etymology
External Crossreferences and Linkouts ( 42 )
Synonyms and Secondary IDs (19)
Reported As
Symbol Synonym
HeT-A
(Eastwood et al., 2021, McGurk et al., 2021, Cacchione et al., 2020, Kordyukova et al., 2020, Markova et al., 2020, Saint-Leandre et al., 2020, Saint-Leandre et al., 2020, Kneuss et al., 2019, Radion et al., 2019, Saint-Leandre et al., 2019, Zhao et al., 2019, Korandová et al., 2018, Kordyukova et al., 2018, Sun et al., 2018, Zhang et al., 2018, Casacuberta, 2017, Radion et al., 2017, Ren et al., 2017, Ryazansky et al., 2017, Cipressa et al., 2016, López-Panadès and Casacuberta, 2016, Wylie et al., 2016, Dehghani and Lasko, 2015, Kofler et al., 2015, Molla-Herman et al., 2015, Senti et al., 2015, Wang et al., 2015, Dufourt et al., 2014, Fulcher et al., 2014, Hayashi et al., 2014, Hayashi et al., 2014, Minakhina et al., 2014, Satyaki et al., 2014, Sytnikova et al., 2014, Wang et al., 2014, Zhang et al., 2014, Brar et al., 2013, Dönertas et al., 2013, Handler et al., 2013, Muerdter et al., 2013, Ohtani et al., 2013, Rozhkov et al., 2013, Silva-Sousa and Casacuberta, 2013, Vagin et al., 2013, Wesolowska et al., 2013, Anand and Kai, 2012, Kofler et al., 2012, Olivieri et al., 2012, Sienski et al., 2012, Sreesankar et al., 2012, Takács et al., 2012, Tan et al., 2012, Debaryshe and Pardue, 2011, Handler et al., 2011, Klenov et al., 2011, Pane et al., 2011, Pardue and Debaryshe, 2011, Shpiz et al., 2011, Wang and Elgin, 2011, Zhang et al., 2011, Fuller et al., 2010, Gao et al., 2010, George et al., 2010, Gou et al., 2010, Khurana et al., 2010, Rozhkov et al., 2010, Traverse et al., 2010, Deloger et al., 2009, Li et al., 2009, Lim et al., 2009, Phalke et al., 2009, Shpiz et al., 2009, Frydrychova et al., 2008, Frydrychova et al., 2008, Kalmykova et al., 2008, Kawamura et al., 2008, Kern and Begum, 2008, Shpiz et al., 2008, Brennecke et al., 2007, Chen et al., 2007, Frydrychova et al., 2007, Gunawardane et al., 2007, Horwich et al., 2007, Klattenhoff et al., 2007, Klenov et al., 2007, Lim and Kai, 2007, Shpiz et al., 2007, Torok et al., 2007, Villasante et al., 2007, Yin and Lin, 2007, Zaratiegui, 2007, George et al., 2006, Maxwell et al., 2006, Oikemus et al., 2006, Vagin et al., 2006, Bi et al., 2005, Raffa et al., 2005, Vagin et al., 2004, Cenci et al., 2003, Mason et al., 2003, Nardon et al., 2003, Savitsky et al., 2002)
HeT-A element
Het
Telo3R
telomeric HeT-A element
Secondary FlyBase IDs
  • FBgn0010279
  • FBgn0004457
  • FBgn0004141
  • FBtp0011436
References (299)