IS1071-mediated recombinational equilibrium in Alcaligenes sp. BR60 carrying the 3-chlorobenzoate catabolic transposon Tn5271

1993 ◽  
Vol 39 (1) ◽  
pp. 92-100 ◽  
Author(s):  
James Ng ◽  
R. Campbell Wyndham
Keyword(s):  
Homologous Recombination ◽  
Parent Strain ◽  
Insertion Sequence ◽  
Class Ii ◽  
Indigenous Plasmid ◽  
Resistant Mutants ◽  
Selection For ◽  
Transposition Mechanism

In experiments designed to Tn5 mutagenize the indigenous plasmid pBRC60 of Alcaligenes sp. BR60, kanamycin-resistant mutants were isolated that were cured of this plasmid and that exhibited recombination of the plasmid-located chlorobenzoate catabolic transposon Tn5271 into the chromosome. These events were independent of the location of Tn5 insertions into the genome of strain BR60. The chromosomal recombinants carried at least two novel copies of IS1071, the class II insertion sequence flanking Tn5271, compared with the parent strain. Recombination of Tn5271 into the chromosome of Alcaligenes sp. BR60 was also detected following mating in of pBRC60-incompatible (IncP1) plasmids, R68 and pGS65. Chromosomal copies of Tn5271 could be mobilized between Alcaligenes strains via plasmids pBRC40 or R68. Conjugation of the incompatible plasmid pGS65 into Alcaligenes strains in the absence of selection for 3-chlorobenzoate catabolism resulted in the recovery of 85% of transconjugants in which the entire pBRC60 plasmid had integrated into the chromosome. These transconjugants exhibited complex rearrangements in chromosomal IS1071 copies. A model of recombinational equilibrium involving homologous recombination between plasmid and chromosomal copies of IS1071 is presented. The results are discussed in terms of the IS1071 (class II) transposition mechanism and the observed products of IS 1071-mediated recombination in natural recipients of pBRC60 in aquatic environments.Key words: transposon, 3-chlorobenzoate catabolism, rearrangement.

scholarly journals Evolution of rhizobial symbiosis islands through insertion sequence-mediated deletion and duplication

2021 ◽  
Author(s):  
Haruka Arashida ◽  
Haruka Odake ◽  
Masayuki Sugawara ◽  
Ryota Noda ◽  
Kaori Kakizaki ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Type Iii Secretion ◽  
Host Plants ◽  
Insertion Sequence ◽  
Marker Gene ◽  
Gene Clusters ◽  
Free Living ◽  
Rhizobial Symbiosis ◽  
Natural Mechanism ◽  
Resistant Mutants

AbstractSymbiosis between organisms influences their evolution via adaptive changes in genome architectures. Immunity of soybean carrying the Rj2 allele is triggered by NopP (type III secretion system [T3SS]-dependent effector), encoded by symbiosis island A (SymA) in B. diazoefficiens USDA122. This immunity was overcome by many mutants with large SymA deletions that encompassed T3SS (rhc) and N2 fixation (nif) genes and were bounded by insertion sequence (IS) copies in direct orientation, indicating homologous recombination between ISs. Similar deletion events were observed in B. diazoefficiens USDA110 and B. japonicum J5. When we cultured a USDA122 strain with a marker gene sacB inserted into the rhc gene cluster, most sucrose-resistant mutants had deletions in nif/rhc gene clusters, similar to the mutants above. Some deletion mutants were unique to the sacB system and showed lower competitive nodulation capability, indicating that IS-mediated deletions occurred during free-living growth and the host plants selected the mutants. Among 63 natural bradyrhizobial isolates, 2 possessed long duplications (261–357 kb) harboring nif/rhc gene clusters between IS copies in direct orientation via homologous recombination. Therefore, the structures of symbiosis islands are in a state of flux via IS-mediated duplications and deletions during rhizobial saprophytic growth, and host plants select mutualistic variants from the resultant pools of rhizobial populations. Our results demonstrate that homologous recombination between direct IS copies provides a natural mechanism generating deletions and duplications on symbiosis islands.

scholarly journals Functional Analysis of Unique Class II Insertion Sequence IS1071

2006 ◽  
Vol 72 (1) ◽  
pp. 291-297 ◽  
Author(s):  
Masahiro Sota ◽  
Hirokazu Yano ◽  
Yuji Nagata ◽  
Yoshiyuki Ohtsubo ◽  
Hiroyuki Genka ◽  
...  
Keyword(s):  
Insertion Sequence ◽  
Insertion Site ◽  
Class Ii ◽  
Target Sequence ◽  
Comamonas Testosteroni ◽  
Transposase Gene ◽  
High Frequencies ◽  
Target Dna ◽  
Functional Features ◽  
Transposition Mechanism

ABSTRACT Various xenobiotic-degrading genes on many catabolic plasmids are often flanked by two copies of an insertion sequence, IS1071. This 3.2-kb IS element has long (110-bp) terminal inverted repeats (IRs) and a transposase gene that are phylogenetically related to those of the class II transposons. However, the transposition mechanism of IS1071 has remained unclear. Our study revealed that IS1071 was only able to transpose at high frequencies in two environmental β-proteobacterial strains, Comamonas testosteroni and Delftia acidovorans, and not in any of the bacteria examined which belong to the α- and γ-proteobacteria. IS1071 was found to have the functional features of the class II transposons in that (i) the final product of the IS1071 transposition was a cointegrate of its donor and target DNA molecules connected by two directly repeated copies of IS1071, one at each junction; (ii) a 5-bp duplication of the target sequence was observed at the insertion site; and (iii) a tnpA mutation of IS1071 was efficiently complemented by supplying the wild-type tnpA gene in trans. Deletion analysis of the IS1071 IR sequences indicated that nearly the entire region of the IRs was required for its transposition, suggesting that the interaction between the transposase and IRs of IS1071 might be different from that of the other well-characterized class II transposons.

scholarly journals Ability of a bacterial chromosome segment to invert is dictated by included material rather than flanking sequence.

Genetics ◽  
1991 ◽  
Vol 129 (4) ◽  
pp. 1021-1032 ◽  
Author(s):  
M J Mahan ◽  
J R Roth
Keyword(s):  
Homologous Recombination ◽  
Parent Strain ◽  
Genetic Material ◽  
Chromosomal Inversion ◽  
Chromosome Segment ◽  
Bacterial Chromosome ◽  
Flanking Sequence ◽  
Flanking Sequences ◽  
Almost All

Abstract Homologous recombination between sequences present in inverse order within the same chromosome can result in inversion formation. We have previously shown that inverse order sequences at some sites (permissive) recombine to generate the expected inversion; no inversions are found when the same inverse order sequences flank other (nonpermissive) regions of the chromosome. In hopes of defining how permissive and nonpermissive intervals are determined, we have constructed a strain that carries a large chromosomal inversion. Using this inversion mutant as the parent strain, we have determined the "permissivity" of a series of chromosomal sites for secondary inversions. For the set of intervals tested, permissivity seems to be dictated by the nature of the genetic material present within the chromosomal interval being tested rather than the flanking sequences or orientation of this material in the chromosome. Almost all permissive intervals include the origin or terminus of replication. We suggest that the rules for recovery of inversions reflect mechanistic restrictions on the occurrence of inversions rather than lethal consequences of the completed rearrangement.

Comparative genome analysis reveals the presence of multiple quorum-sensing systems in plant pathogenic bacterium, Erwinia rhapontici

2021 ◽  
Author(s):  
Tomohiro Morohoshi ◽  
Kanako Nameki ◽  
Nobutaka Someya
Keyword(s):  
Gene Pair ◽  
Large Scale ◽  
Insertion Sequence ◽  
Plant Pathogenic Bacterium ◽  
Comparative Genome Analysis ◽  
Genome Sequences ◽  
Indigenous Plasmid ◽  
Acylhomoserine Lactone ◽  
Sensing Systems ◽  
Erwinia Rhapontici

Abstract We present the complete genome sequences of three Erwinia rhapontici strains, MAFF 311153, 311154, and 311155. These chromosome sequences contained variety types of luxI/luxR gene pair involved in acylhomoserine lactone (AHL) biosynthesis and reception. Large-scale insertion sequence was observed in the indigenous plasmid of MAFF 311154 and contained eraI3/eraR3 gene pair which make possible to produce acylhomoserine lactone.

Identification of a chromosomal region required for biosynthesis of the phytotoxin coronatine by Pseudomonas syringae pv. tomato

1989 ◽  
Vol 35 (10) ◽  
pp. 910-917 ◽  
Author(s):  
R. A. Moore ◽  
A. N. Starratt ◽  
S.-W. Ma ◽  
V. L. Morris ◽  
D. A. Cuppels
Keyword(s):  
Pseudomonas Syringae ◽  
Genomic Dna ◽  
Chromosomal Region ◽  
Enzyme Analysis ◽  
Restriction Enzyme Analysis ◽  
Wild Type ◽  
Tomato Dc3000 ◽  
Indigenous Plasmid ◽  
Insertion Sites ◽  
Resistant Mutants

Pseudomonas syringae pv. tomato produces the chlorosis-inducing phytotoxin coronatine. Five of 3700 (0.13%) kanamycin-resistant mutants generated by random Tn5 mutagenesis were unable to synthesize this toxin. Clone pEC18, isolated from a cosmid pLAFR1 library of wild-type P. syringae pv. tomato DC3000 genomic DNA, complemented four of the mutants. Restriction enzyme analysis of pEC18 and corresponding clones from the four mutants indicated that the Tn5 insertion sites of these four mutants spanned a 19-kb region of DC3000 genomic DNA. Complementation tests with subclones of pEC18 confirmed the relative locations of the Tn5 insertions. Because pEC18 did not complement all five mutants or confer the ability to produce toxin on nonproducing P. syringae pathovars, sequences outside this cloned region must also be involved in toxin synthesis. As demonstrated by Southern blot analysis, this cloned region was not on the 68-kb indigenous plasmid of DC3000. The only P. syringae pathovars with DNA homologous to sequences within the coronatine gene cluster were the coronatine producers P. syringae pv. tomato, P. syringae pv. atropurpurea, and P. syringae pv. glycinea. Since the hybridization patterns of these toxin producers were identical, this locus is highly conserved and appears crucial to the synthesis of coronatine.Key words: coronatine, phytotoxin mutants, Pseudomonas syringae pv. tomato.

scholarly journals Therapeutic targeting and patient selection for cancers with homologous recombination defects

2017 ◽  
Vol 12 (6) ◽  
pp. 565-581 ◽  
Author(s):  
Francien Talens ◽  
Mathilde Jalving ◽  
Jourik A. Gietema ◽  
Marcel A. Van Vugt
Keyword(s):  
Homologous Recombination ◽  
Patient Selection ◽  
Therapeutic Targeting ◽  
Selection For

Genetic determinant(s) for D-cycloserine resistance in Staphylococcus aureus

1971 ◽  
Vol 17 (10) ◽  
pp. 1267-1271
Author(s):  
Marcia A. Miller ◽  
Melvin S. Rheins
Keyword(s):  
Staphylococcus Aureus ◽  
Elevated Temperature ◽  
Satellite Dna ◽  
Parent Strain ◽  
Buoyant Density ◽  
Single Step ◽  
Low Grade ◽  
Genetic Determinant ◽  
Resistant Mutants

The characterization of the genetic determinant(s) governing resistance to the antibiotic D-cycloserine in Staphylococcus aureus U9W was described. Only single-step low-grade resistant mutants developed from the parent strain, which was originally sensitive to the antibiotic. After exposure of resistant mutants to acridine orange and (or) elevated temperature, D-cycloserine-sensitive segregants were recovered. No resistant recombinants were obtained from transduction experiments using various D-cycloserine-sensitive "cured" mutants as donors. Buoyant density studies, however, did not reveal satellite DNA.

Lipid composition and polyene antibiotic resistance of Candida albicans mutants

1978 ◽  
Vol 56 (2) ◽  
pp. 135-142 ◽  
Author(s):  
A. M. Pierce ◽  
H. D. Pierce Jr. ◽  
A. M. Unrau ◽  
A. C. Oehlschlager
Keyword(s):  
Fatty Acids ◽  
Candida Albicans ◽  
Parent Strain ◽  
Total Sterol ◽  
Phospholipid Fatty Acids ◽  
Sterol Esters ◽  
Free Sterols ◽  
Major Sterol ◽  
Resistant Mutants ◽  
The Individual

Four polyene-resistant mutants (C7, E4, C4, D10) of Candida albicans were derived by mutagenesis with N-methyl-N′-nitro-N-nitrosoguanidine followed by isolation on nystatin-containing medium. The mutants were cross resistant to amphotericin B, lucensomycin, and candicidin and showed the same order of increasing resistance to the four polyenes tested, i.e., C7 < E4 < C4 < D10. Free sterols, sterol esters, and phospholipid fatty acids were analyzed in the mutants and sensitive parent strain. The lipids of C7 were the same as those of the sensitive parent strain. Mutant E4 contained lichesterol and other Δ8-sterols indicating a block at the Δ8→ Δ7 isomerase, and most of the sterol ester fraction consisted of 4,14-desmethyl sterols. The most resistant mutants C4 and D10 had reduced growth rates, alterations in phospholipid fatty acids, and the absence of 4,14-desmethyl sterols. Mutants C4 and D10 had similar lipid compositions with 24-methylenelanosterol as the major sterol and lesser amounts of obtusifoliol and lanosterol. The proportion of the total sterol that was esterified was low and similar (19–34%) in cultures of the mutants and of the sensitive strain harvested in the same stage of stationary growth. Total sterol content, however, increased with resistance. Polyene resistance was better correlated with the type of sterols in the total sterol pools rather than with the degree of esterification of the individual sterols, i.e., resistance increased with the presence of Δ8- and 4,14-methyl sterols. Our data indicate that factors other than or in addition to alterations in sterol and phospholipid patterns account for polyene resistance.

scholarly journals Transposable Element Loads in a Bacterial Symbiont of Weevils Are Extremely Variable

2008 ◽  
Vol 74 (24) ◽  
pp. 7832-7834 ◽  
Author(s):  
Kevin M. Dougherty ◽  
Gordon R. Plague
Keyword(s):  
Homologous Recombination ◽  
Transposable Elements ◽  
Transposable Element ◽  
Insertion Sequence ◽  
Bacterial Symbiont ◽  
Genomic Variation ◽  
Bacterial Endosymbiont

ABSTRACT Not only are transposable elements profuse in the bacterial endosymbiont of maize weevils, but we found that their quantities also vary ∼10-fold among individual weevils. Because multicopy elements can facilitate homologous recombination, this insertion sequence (IS) load variability suggests that these essentially asexual bacteria may exhibit substantial intraspecific genomic variation.

Ineffectiveness of viomycin-resistant mutants of Rhizobium meliloti

1969 ◽  
Vol 15 (7) ◽  
pp. 671-675 ◽  
Author(s):  
G. S. Hendry ◽  
D. C. Jordan
Keyword(s):  
Cell Wall ◽  
Nitrogen Fixation ◽  
Parent Strain ◽  
Rhizobium Meliloti ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Effective Strain ◽  
One Step ◽  
Increased Sensitivity ◽  
Resistant Mutants

Under clearly defined conditions one-step acquisition of viomycin resistance by a normally effective strain of Rhizobium meliloti resulted in one-step acquisition of ineffectiveness in nitrogen fixation, which probably occurred with a one-gene change in the R. meliloti genome. Two-step mutants retained their ability to produce root nodules but such nodules also were ineffective. Increased sensitivity of the viomycin-resistant mutants to glycine and D-alanine was not noted. Bacteroids were not seen in nodules formed by the viomycin-resistant mutants on their homologous host plant. Nitrogenase activity was not detected, by acetylene reduction, in detached ineffective nodules, whereas effective nodules formed 10.6 μmoles of ethylene per hour per gram of nodules. Growth of the effective parent strain in a low concentration of viomycin resulted in elongation and swelling of the cells so that they appeared as artificially produced bacteroids. Viomycin-resistant mutants did not undergo this transformation. Antigens could be readily extracted by hot- and cold-saline extraction of wet packed cells of both resistant and sensitive cultures but antigenic differences, which may have indicated cell wall differences, were not noted.

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