scholarly journals Microuli, a Family of Miniature Subterminal Inverted-Repeat Transposable Elements (MSITEs): Transposition Without Terminal Inverted Repeats

2001 ◽  
Vol 18 (5) ◽  
pp. 893-895 ◽  
Author(s):  
Zhijian Tu ◽  
Stephanos P. Orphanidis
2002 ◽  
Vol 68 (5) ◽  
pp. 2307-2315 ◽  
Author(s):  
Masahiro Sota ◽  
Masahiro Endo ◽  
Keiji Nitta ◽  
Haruhiko Kawasaki ◽  
Masataka Tsuda

ABSTRACT The two haloacetate dehalogenase genes, dehH1 and dehH2, on the 65-kb plasmid pUO1 from Delftia acidovorans strain B were found to be located on transposable elements. The dehH2 gene was carried on an 8.9-kb class I composite transposon (TnHad1) that was flanked by two directly repeated copies of IS1071, IS1071L and IS1071R. The dehH1 gene was also flanked by IS1071L and a truncated version of IS1071 (IS1071N). TnHad1, dehH1, and IS1071N were located on a 15.6-kb class II transposon (TnHad2) whose terminal inverted repeats and res site showed high homology with those of the Tn21-related transposons. TnHad2 was defective in transposition because of its lacking the transposase and resolvase genes. TnHad2 could transpose when the Tn21-encoded transposase and resolvase were supplied in trans. These results demonstrated that Tn Had2 is a defective Tn21-related transposon carrying another class I catabolic transposon.


2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Ann A. Ferguson ◽  
Ning Jiang

Mutator-like transposable elements (MULEs) are widespread in plants and the majority have long terminal inverted repeats (TIRs), which distinguish them from other DNA transposons. It is known that the long TIRs ofMutatorelements harbor transposase binding sites and promoters for transcription, indicating that the TIR sequence is critical for transposition and for expression of sequences between the TIRs. Here, we report the presence of MULEs with multiple TIRs mostly located in tandem. These elements are detected in the genomes of maize, tomato, rice, andArabidopsis. Some of these elements are present in multiple copies, suggesting their mobility. For those elements that have amplified, sequence conservation was observed for both of the tandem TIRs. For one MULE family carrying a gene fragment, the elements with tandem TIRs are more prevalent than their counterparts with a single TIR. The successful amplification of this particular MULE demonstrates that MULEs with tandem TIRs are functional in both transposition and duplication of gene sequences.


2017 ◽  
Vol 69 (2) ◽  
pp. 353-360 ◽  
Author(s):  
Salma Djebbi ◽  
Amara Ben ◽  
Hanem Makni ◽  
Mohamed Makni ◽  
Maha Mezghani-Khemakhem

Mariner-like elements (MLEs) are Class-II transposons that are widely present in diverse organisms and encode a D,D34D transposase motif. MLE sequences from two coleopteran species, Bruchuspisorum and B. rufimanus were obtained using the terminal-inverted repeats (TIRs) of mariner elements belonging to the mauritiana subfamily as primer. The characterized elements were between 1073 and 1302 bp in length and are likely to be inactive, based on the presence of multiple stop codons and/or frameshifts. A single consensus of MLE was detected in B. pisorum and was named Bpmar1. This element exhibited several conserved amino acid blocks as well as the specific D,D(34)D signature. As for B. rufimanus, two MLE consensuses, designated Brmar1 and Brmar2, were isolated, both containing deletions overlapping the internal region of the transposase. Structural and phylogenetic analysis of these sequences suggested a relatively recent origin of Bpmar1 versus a more ancient invasion of Brmar1 and Brmar2 in their respective host genomes. Given that MLEs are potential mediators of insect resistance and have been used as vectors to transfer genes into host genomes, the MLEs characterized in this study will have valuable implications for selecting appropriate transposable elements in transgenesis.


Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 845-854 ◽  
Author(s):  
M M Qin ◽  
D S Robertson ◽  
A H Ellingboe

Abstract The identification of the autonomous or transposase-encoding element of the Mutator (Mu) transposable element system of maize is necessary to the characterization of the system. We reported previously that a transcript homologous to the internal region of the MuA element is associated with activity of the Mutator system. We describe here the cloning of another Mu element, designated MuA2, that cosegregates with Mutator activity as assayed by somatic instability of the a1-Mum2 allele. The MuA2 element has features typical of the transposable elements of the Mutator family, including the 210-bp terminal inverted repeats. Several lines of evidence suggest that MuA2 is an autonomous or transposase-encoding element of the Mu family: (1) MuA2 cosegregates with a genetically defined element that regulates somatic mutability of the a1-Mum2 allele; (2) MuA2 is hypomethylated while most other MuA2-hybridizing sequences in the genome are extensively methylated; (3) the increase of the copy number of MuA2 is concomitant with the increase of regulator elements; (4) MuA2-like elements are found in Mutator lines but not in non-Mutator inbreds. We propose that autonomous or transposase-encoding elements of the Mu family may be structurally conserved and MuA2-like.


1989 ◽  
Vol 9 (7) ◽  
pp. 3018-3027 ◽  
Author(s):  
J E Garrett ◽  
D S Knutzon ◽  
D Carroll

Members of two related families of transposable elements, Tx1 and Tx2, were isolated from the genome of Xenopus laevis and characterized. In both families, two versions of the elements were found. The smaller version in each family (Tx1d and Tx2d) consisted largely of two types of 400-base-pair tandem internal repeats. These elements had discrete ends and short inverted terminal repeats characteristic of mobile DNAs that are presumed to move via DNA intermediates, e.g., Drosophila P and maize Ac elements. The longer versions (Tx1c and Tx2c) differed from Tx1d and Tx2d by the presence of a 6.9-kilobase-pair internal segment that included two long open reading frames (ORFs). ORF1 had one cysteine-plus-histidine-rich sequence of the type found in retroviral gag proteins. ORF2 showed more substantial homology to retroviral pol genes and particularly to the analogs of pol found in a subclass of mobile DNAs that are supposed retrotransposons, such as mammalian long interspersed repetitive sequences, Drosophila I factors, silkworm R1 elements, and trypanosome Ingi elements. Thus, the Tx1 elements present a paradox by exhibiting features of two classes of mobile DNAs that are thought to have very different modes of transposition. Two possible resolutions are considered: (i) the composite versions are actually made up of two independent elements, one of the retrotransposon class, which has a high degree of specificity for insertion into a target within the other, P-like element; and (ii) the composite elements are intact, autonomous mobile DNAs, in which the pol-like gene product collaborates with the terminal inverted repeats to cause transposition of the entire unit.


2003 ◽  
Vol 185 (21) ◽  
pp. 6371-6384 ◽  
Author(s):  
Sally R. Partridge ◽  
Ruth M. Hall

ABSTRACT IS5075 and IS4321 are closely related (93.1% identical) members of the IS1111 family that target a specific position in the 38-bp terminal inverted repeats of Tn21 family transposons and that are inserted in only one orientation. They are 1,327 bp long and have identical ends consisting of short inverted repeats of 12 bp with an additional 7 bp (TAATGAG) or 6 bp (AATGAG) to the left of the left inverted repeats and 3 bp (AGA) or 4 bp (AGAT) to the right of the right inverted repeat. Circular forms of IS5075 and IS4321 in which the inverted repeats are separated by abutting terminal sequences (AGATAATGAG) were detected. A similar circular product was found for the related ISPa11. Transposition of IS4321 into the 38-bp target site was detected, but a flanking duplication was not generated. The precisely reconstituted target site was also identified. Over 50 members of the IS1111 family were identified. They encode related transposases, have related inverted repeats, and include related bases that lie outside these inverted repeats. In some, the flanking bases number 5 or 6 on the left and 4 or 3 on the right. Specific target sites were found for several of these insertion sequence (IS) elements. IS1111 family members therefore differ from the majority of IS elements, which are characterized by terminal inverted repeats and a target site duplication, and from members of the related IS110 family, which do not have obvious inverted repeats near their termini.


Genetics ◽  
1991 ◽  
Vol 129 (1) ◽  
pp. 261-270 ◽  
Author(s):  
P Chomet ◽  
D Lisch ◽  
K J Hardeman ◽  
V L Chandler ◽  
M Freeling

Abstract The Mutator system of maize consists of more than eight different classes of transposable elements each of which can be found in multiple copies. All Mu elements share the approximately 220-bp terminal inverted repeats, whereas each distinct element class is defined by its unique internal sequences. The regulation of instability of this system has been difficult to elucidate due to its multigenic inheritance. Here we present genetic experiments which demonstrate that there is a single locus, MuR1, which can regulate the transposition of Mu1 elements. We describe the cloning of members of a novel class of Mu elements, MuR, and demonstrate that a member of the class is the regulator of Mutator activity, MuR1. This conclusion is based on several criteria: MuR1 activity and a MuR-homologous restriction fragment cosegregate; when MuR1 undergoes a duplicative transposition, an additional MuR restriction fragment is observed, and MuR1 activity and the cosegregating MuR fragment are simultaneously lost within clonal somatic sectors. In addition, the MuR element hybridizes to transcripts in plants with Mutator activity. Our genetic experiments demonstrate that the MuR1 transposon is necessary to specify Mutator activity in our lines.


1989 ◽  
Vol 9 (7) ◽  
pp. 3018-3027
Author(s):  
J E Garrett ◽  
D S Knutzon ◽  
D Carroll

Members of two related families of transposable elements, Tx1 and Tx2, were isolated from the genome of Xenopus laevis and characterized. In both families, two versions of the elements were found. The smaller version in each family (Tx1d and Tx2d) consisted largely of two types of 400-base-pair tandem internal repeats. These elements had discrete ends and short inverted terminal repeats characteristic of mobile DNAs that are presumed to move via DNA intermediates, e.g., Drosophila P and maize Ac elements. The longer versions (Tx1c and Tx2c) differed from Tx1d and Tx2d by the presence of a 6.9-kilobase-pair internal segment that included two long open reading frames (ORFs). ORF1 had one cysteine-plus-histidine-rich sequence of the type found in retroviral gag proteins. ORF2 showed more substantial homology to retroviral pol genes and particularly to the analogs of pol found in a subclass of mobile DNAs that are supposed retrotransposons, such as mammalian long interspersed repetitive sequences, Drosophila I factors, silkworm R1 elements, and trypanosome Ingi elements. Thus, the Tx1 elements present a paradox by exhibiting features of two classes of mobile DNAs that are thought to have very different modes of transposition. Two possible resolutions are considered: (i) the composite versions are actually made up of two independent elements, one of the retrotransposon class, which has a high degree of specificity for insertion into a target within the other, P-like element; and (ii) the composite elements are intact, autonomous mobile DNAs, in which the pol-like gene product collaborates with the terminal inverted repeats to cause transposition of the entire unit.


2003 ◽  
Vol 185 (13) ◽  
pp. 3753-3763 ◽  
Author(s):  
Dariusz Bartosik ◽  
Marta Sochacka ◽  
Jadwiga Baj

ABSTRACT We studied diversity and distribution of transposable elements residing in different strains (DSM 11072, DSM 11073, DSM 65, and LMD 82.5) of a soil bacterium Paracoccus pantotrophus (α-Proteobacteria). With application of a shuttle entrapment vector pMEC1, several novel insertion sequences (ISs) and transposons (Tns) have been identified. They were sequenced and subjected to detailed comparative analysis, which allowed their characterization (i.e., identification of transposase genes, terminal inverted repeats, as well as target sequences) and classification into the appropriate IS or Tn families. The frequency of transposition of these elements varied and ranged from 10−6 to 10−3 depending on the strain. The copy number, localization (plasmid or chromosome), and distribution of these elements in the Paracoccus species P. pantotrophus, P. denitrificans, P. methylutens, P. solventivorans, and P. versutus were analyzed. This allowed us to distinguish elements that are common in paracocci (ISPpa2, ISPpa3—both of the IS5 family—and ISPpa5 of IS66 family) as well as strain-specific ones (ISPpa1 of the IS256 family, ISPpa4 of the IS5 family, and Tn3434 and Tn5393 of the Tn3 family), acquired by lateral transfer events. These elements will be of a great value in the design of new genetic tools for paracocci, since only one element (IS1248 of P. denitrificans) has been described so far in this genus.


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