scholarly journals Ac induces homologous recombination at the maize P locus.

Genetics ◽  
1991 ◽  
Vol 128 (1) ◽  
pp. 163-173 ◽  
Author(s):  
P Athma ◽  
T Peterson
Keyword(s):  
Homologous Recombination ◽  
Transposable Element ◽  
Direct Repeat ◽  
Null Alleles ◽  
Direct Repeats ◽  
Ac Element ◽  
Repeat Sequences ◽  
P Gene ◽  
In Trans ◽  
P Locus

Abstract The maize P gene conditions red phlobaphene pigmentation to the pericarp and cob. Starting from two unstable P alleles which carry insertions of the transposable element Ac, we have derived 51 P null alleles; 47 of the 51 null alleles have a 17-kb deletion which removes the 4.5-kb Ac element and 12.5 kb of P sequences flanking both sides of Ac. The deletion endpoints lie within two 5.2-kb homologous direct repeats which flank the P gene. A P allele which contains the direct repeats, but does not have an Ac insertion between the direct repeats, shows very little sporophytic or gametophytic instability. The apparent frequency of sporophytic mutations was not increased when Ac was introduced in trans. Southern analysis of DNA prepared from the pericarp tissue demonstrates that the deletions can occur premeiotically, in the somatic cells during development of the pericarp. Evidence is presented that the deletions occurred by homologous recombination between the two direct repeats, and that the presence of an Ac element at the P locus is associated with the recombination/deletion. These results add another aspect to the spectrum of activities of Ac: the destabilization of flanking direct repeat sequences.

Ac Insertion Site Affects the Frequency of Transposon-Induced Homologous Recombination at the Maize p1 Locus

Genetics ◽  
2000 ◽  
Vol 156 (4) ◽  
pp. 2007-2017
Author(s):  
Yong-Li Xiao ◽  
Xianggan Li ◽  
Thomas Peterson
Keyword(s):  
Homologous Recombination ◽  
Transposable Element ◽  
Recombination Frequency ◽  
Insertion Site ◽  
Direct Repeat ◽  
Red Pigment ◽  
Direct Repeats ◽  
Coding Region ◽  
Repeat Sequences ◽  
Gene Coding

Abstract The maize p1 gene regulates the production of a red pigment in the kernel pericarp, cob, and other maize floral tissues. Insertions of the transposable element Ac can induce recombination between two highly homologous 5.2-kb direct repeat sequences that flank the p1 gene-coding region. Here, we tested the effects of the Ac insertion site and orientation on the induction of recombination at the p1 locus. A collection of unique p1 gene alleles was used, which carry Ac insertions at different sites in and near the p1 locus, outside of the direct repeats, within the direct repeat sequences, and between the direct repeats, in both orientations. Recombination was scored by the numbers of colorless pericarp sectors (somatic frequency) and heritable mutations (germinal frequency). In both the somatic and germinal tests, the frequency of homologous recombination is significantly higher when Ac is inserted between the direct repeats than when Ac is inserted either within or outside the repeats. In contrast, Ac orientation had no significant effect on recombination frequency. We discuss these results in terms of the possible mechanisms of transposon-induced recombination.

scholarly journals The 3′ untranslated regions of Kamiti River virus and Cell fusing agent virus originated by self-duplication

2006 ◽  
Vol 87 (9) ◽  
pp. 2615-2619 ◽  
Author(s):  
T. S. Gritsun ◽  
E. A. Gould
Keyword(s):  
Direct Repeat ◽  
Large Deletion ◽  
Untranslated Regions ◽  
Direct Repeats ◽  
Repeat Sequences ◽  
Tick Borne Encephalitis ◽  
Perfect Repeat ◽  
Tick Borne Encephalitis Virus ◽  
Complete Duplication ◽  
Nucleotide Alignment

Previously, it was shown that the 3′ untranslated region (3′UTR) of Kamiti River virus (KRV) is nearly twice as long as the 3′UTR of other flaviviruses (1208 nucleotides compared with 730 nucleotides for the longest 3′UTR of any virus in the Tick-borne encephalitis virus species). Additionally, KRV and the closely related Cell fusing agent virus (CFAV) were shown to contain two short, almost perfect repeat sequences of 67 nucleotides. However, the construction of a robust comparative nucleotide alignment has now revealed that the double-length 3′UTR and the direct repeats resulted from the virtually complete duplication of a primordial KRV 3′UTR. We also propose that the CFAV 3′UTR was derived from a KRV-like precursor sequence with a large deletion that nevertheless preserved the two direct repeat sequences. These data provide new insights into the evolution of the flavivirus 3′UTR.

Conservation of a satellite DNA sequence (SATB) in the tilapiine and haplochromine genome (Pisces: Cichlidae)

Genome ◽  
1993 ◽  
Vol 36 (1) ◽  
pp. 187-194 ◽  
Author(s):  
Jens P. C. Franck ◽  
Jonathan M. Wright
Keyword(s):  
Satellite Dna ◽  
Direct Repeat ◽  
Repeat Sequence ◽  
South American ◽  
Direct Repeats ◽  
Core Motif ◽  
Hindiii Fragment ◽  
Sequence Identity ◽  
Repeat Sequences ◽  
Internal Component

We have cloned and sequenced a 1900-bp EcoRI fragment (SATB) from the tilapiine fish Oreochromis niloticus. The SATB sequence is highly reiterated in the tilapiine genome and organized in long tandem arrays. A 760-bp HindIII fragment, an internal component of SATB, has also been cloned and sequenced from the related tilapiine species Oreochromis hornorum. Hybridization of the radiolabeled 760-bp HindIII repeat detected the presence of the SATB repeat in the genomes of several tilapiine species as well as the haplochromine species Haplochromis (Protomelas) similis. The 760-bp HindIII fragment did not hybridize to genomic DNA of Etroplus maculatus (an Asian cichlid) or to that of Cichlasoma meeki (a South American cichlid). The SATB repeat sequence is 56% AT and constitutes 0.2–5% of the tilapiine genome depending on the species examined. Four imperfect 21-bp direct repeat sequences are present within the cloned 1900-bp EcoRI repeat. Alignment of the four direct repeats from the O. niloticus cloned 1900-bp DNA and the two homologous direct repeats from the O. hornorum 760-bp HindIII repeat revealed a core motif of 11 bp that exhibits 100% sequence identity between all of the direct repeats. The conservation of this motif in the SATB repeat suggests that this sequence may be under selective constraint.Key words: satellite DNA, Cichlidae, direct repeats.

Rec A-independent homologous recombination induced by a putative fold-back tetraplex DNA

2006 ◽  
Vol 387 (3) ◽  
pp. 251-256 ◽  
Author(s):  
Arun Kumar Shukla ◽  
Kunal B. Roy
Keyword(s):  
Homologous Recombination ◽  
Biological Significance ◽  
Direct Repeat ◽  
Repeat Sequence ◽  
Significant Implication ◽  
Repeat Sequences ◽  
Close Proximity ◽  
To Come ◽  
First Time

Abstract We have recently reported that a GC-rich palindromic repeat sequence presumably adopts a stable fold-back tetraplex DNA structure under supercoiling. To establish the biological significance of this structure, we inserted this sequence between two direct repeat sequences, separated by 200 bp, in a plasmid. We then investigated the effect of this sequence on homologous recombination events. Here we report that the putative fold-back DNA tetraplex structure induces homologous recombination between direct repeat sequences. Interestingly, this recombination event is independent of recA, a major driving force for homologous recombination. We think that the fold-back structure forces the repeat sequences to come into close proximity and therefore leads to strand exchange. Although triplex-induced recombination has been well documented, our results for the first time directly establish the potential of a tetraplex structure to induce recA-independent homologous recombination in vivo. This finding might have a significant implication for site-directed gene deletion in the context of the correction of genetic defects.

scholarly journals Mobilization of a Tn402-Like Class 1 Integron with a Novel Cassette Array via Flanking Miniature Inverted-Repeat Transposable Element-Like Structures

2009 ◽  
Vol 75 (18) ◽  
pp. 6002-6004 ◽  
Author(s):  
Michael R. Gillings ◽  
Maurizio Labbate ◽  
Ammara Sajjad ◽  
Nellie J. Giguère ◽  
Marita P. Holley ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Transposable Element ◽  
Inverted Repeat ◽  
Methionine Sulfoxide ◽  
Methionine Sulfoxide Reductase ◽  
Direct Repeats ◽  
Class 1 Integron ◽  
Class 1

ABSTRACT A Tn402-like class 1 integron was recovered from a prawn-associated bacterium. One of its cassettes included methionine sulfoxide reductase genes, the first example of such genes being captured by an integron. The integron was flanked by direct repeats that resemble miniature inverted-repeat transposable element sequences. Excision of the integron by homologous recombination through these sequences was demonstrated.

scholarly journals Intragenic transposition of Ac generates a new allele of the maize P gene.

Genetics ◽  
1990 ◽  
Vol 126 (2) ◽  
pp. 469-476 ◽  
Author(s):  
T Peterson
Keyword(s):  
Transposable Elements ◽  
Transposable Element ◽  
Single Event ◽  
Opposite Orientation ◽  
Ac Element ◽  
P Gene ◽  
Expression Of Genes

Abstract The maize P gene is required for the production of red phlobaphene pigments in the pericarp and cob. The P-vv allele, which specifies variegated pericarp and cob, contains an insertion of the transposable element Ac in the P gene. A new P-ovov allele (orange variegated pericarp and cob) was obtained as a single event mutation from P-vv. In contrast to the progenitor P-vv allele, P-ovov provides substantial pericarp and cob pigmentation and produces significant amounts of normal-sized P transcripts. The Ac element is not detectably altered in the P-ovov allele, but it has transposed to a new position within P that is 161 bp distant and inserted in the opposite orientation. This example provides molecular confirmation for the hypothesis that changes in expression of genes bearing insertions of transposable elements can occur via movement of the element to new sites within the gene.

scholarly journals Pathways for Homologous Recombination Between Chromosomal Direct Repeats in Salmonella typhimurium

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 751-767 ◽  
Author(s):  
Timothy Galitski ◽  
John R Roth
Keyword(s):  
Homologous Recombination ◽  
Strand Break ◽  
Dna Lesions ◽  
General View ◽  
Direct Repeats ◽  
Sexual Recombination ◽  
Sister Chromosome ◽  
Lactose Utilization ◽  
Recf Pathway ◽  
Chromosome Exchanges

Homologous recombination pathways probably evolved primarily to accomplish chromosomal repair and the formation and resolution of duplications by sister-chromosome exchanges. Various DNA lesions initiate these events. Classical recombination assays, involving bacterial sex, focus attention on double-strand ends of DNA. Sexual exchanges, initiated at these ends, depend on the RecBCD pathway. In the absence of RecBCD function, mutation of the sbcB and sbcC genes activates the apparently cryptic RecF pathway. To provide a more general view of recombination, we describe an assay in which endogenous DNA damage initiates recombination between chromosomal direct repeats. The repeats flank markers conferring lactose utilization (Lac+) and ampicillin resistance (ApR); recombination generates Lac-ApS segregants. In this assay, the RecF pathway is not cryptic; it plays a major role without sbcBC mutations. Others have proposed that single-strand gaps are the natural substrate for RecF-dependent recombination. Supporting this view, recombination stimulated by a double-strand break (DSB) in a chromosomal repeat depended on RecB function, not RecF function. Without RecBCD function, sbcBC mutations modified the RecF pathway and allowed it to catalyze DSB-stimulated recombination. Sexual recombination assays overestimate the importance of RecBCD and DSBs, and underestimate the importance of the RecF pathway.

scholarly journals Formation of Large Palindromic DNA by Homologous Recombination of Short Inverted Repeat Sequences in Saccharomyces cerevisiae

Genetics ◽  
2002 ◽  
Vol 161 (3) ◽  
pp. 1065-1075
Author(s):  
David K Butler ◽  
David Gillespie ◽  
Brandi Steele
Keyword(s):  
Homologous Recombination ◽  
Inverted Repeat ◽  
Excision Repair ◽  
Strand Break ◽  
Double Strand Break ◽  
Repeat Sequence ◽  
Inverted Repeat Sequence ◽  
Repeat Sequences ◽  
Dna Double Strand Break ◽  
Intermolecular Reaction

Abstract Large DNA palindromes form sporadically in many eukaryotic and prokaryotic genomes and are often associated with amplified genes. The presence of a short inverted repeat sequence near a DNA double-strand break has been implicated in the formation of large palindromes in a variety of organisms. Previously we have established that in Saccharomyces cerevisae a linear DNA palindrome is efficiently formed from a single-copy circular plasmid when a DNA double-strand break is introduced next to a short inverted repeat sequence. In this study we address whether the linear palindromes form by an intermolecular reaction (that is, a reaction between two identical fragments in a head-to-head arrangement) or by an unusual intramolecular reaction, as it apparently does in other examples of palindrome formation. Our evidence supports a model in which palindromes are primarily formed by an intermolecular reaction involving homologous recombination of short inverted repeat sequences. We have also extended our investigation into the requirement for DNA double-strand break repair genes in palindrome formation. We have found that a deletion of the RAD52 gene significantly reduces palindrome formation by intermolecular recombination and that deletions of two other genes in the RAD52-epistasis group (RAD51 and MRE11) have little or no effect on palindrome formation. In addition, palindrome formation is dramatically reduced by a deletion of the nucleotide excision repair gene RAD1.

Sign in / Sign up

Export Citation Format

Share Document