IS4 is still found at its chromosomal site after transposition to galT

Klaer, R.; Pfeifer, Dietrich; Starlinger, Peter

doi:10.1007/bf00270473

Cited by 16 publications

(6 citation statements)

References 23 publications

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“…IS2 insertion occurs at only two sites in the operator domain (29), and IS4 has been repeatedly observed to integrate into a single site in the galTgene (30). Thus, the apparent specificity of insertion in eps is consistent with integration properties of IS.…”

Section: Discussionmentioning

confidence: 83%

“…Cosmid vector "arms" were ligated with donor DNA by the method of Franklin (18). Sau3A partially digested donor DNA in the size range of [25][26][27][28][29][30][31][32][33][34][35][36][37] kilobase pairs (kbp) was prepared as described by Maniatis et al (19). In vitro packaging of ligated DNA was accomplished by using Gigapack Plus (Stratagene) A DNA packaging extracts according to the manufacturer's instructions.…”

Section: Methodsmentioning

confidence: 99%

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Variable expression of extracellular polysaccharide in the marine bacterium Pseudomonas atlantica is controlled by genome rearrangement

Bartlett

Wright

Silverman

1988

Proc. Natl. Acad. Sci. U.S.A.

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Production ofextracellular polysaccharide by the marine bacterium Pseudomonas atantica is a variable trait. Strains that produce extracellular polysaccharide (EPS +) have a mucoid colony phenotype, but during cultivation in the laboratory nonmucoid, EPS -variants arise that have a crenated colony morphology. This change is reversible since crenated variants rapidly switch to the original mucoid phenotype. We have cloned the locus (eps) controlling variable expression of EPS production by screening a recombinant cosmid library for clones that restore EPS production in the crenated variant. By using eps as a probe of genomic structure in variant strains, expression of EPS production was found to be controlled by a specific DNA rearrangement. Insertion of a 1.2-kilobase-pair DNA sequence in the eps locus results in EPS -, whereas excision of the sequence restores the EPS + phenotype. Properties of the rearrangement suggest the involvement of a mobile genetic element. The possible significance of this DNA rearrangement to the survival ofP. atlantica in the ocean is discussed.Pseudomonas atlantica attaches to and colonizes a variety of surfaces in the marine environment (1). The ability of a bacterium to elaborate adhesins for binding to a given substratum may be critical to its survival in the ocean because nutrients, which are scarce in seawater, are more abundant on animate surfaces, biofilms, or surfaces with adsorbed organic matter (2). Components associated with the cell envelope such as flagellar and fimbrial appendages, outer membrane proteins, lipopolysaccharides, and extracellular polysaccharides (EPS) function in a large variety of interactions between bacteria and surfaces. With P. atlantica, production of an acidic EPS is thought to be a primary determinant of cell adhesiveness (3).As part of an investigation of the genetic regulation of polysaccharide synthesis in P. atlantica we sought to isolate mutants defective in EPS production. However, EPSstrains were observed to arise spontaneously at frequencies greater than those expected for mutational events. The EPS "variants" are distinguished by their colony morphology. The parental EPS + phenotype is mucoid (M), and the EPSvariants display either a crenated (C) or translucent (T) colony morphology. M and nonmucoid (non-M) variants of Pseudomonas aeruginosa and Pseudomonas fluorescens have also been described (4,5). The genetic mechanisms regulating variable expression of some properties of pathogenic bacteria-i.e., phase variation of flagella in Salmonella and pili variation in Escherichia coli and Neisseria-have been determined (6-8). These variable systems are controlled by complex genomic rearrangements that apparently function to generate antigenic diversity in surface components to allow the pathogens to evade the host immune system. Mechanisms that generate diversity-for example, of adhesive forms-could be important to the survival of marine bacteria as well. Furthermore, insight into novel strategies regulating gene expression might be dis...

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Section: Discussionmentioning

confidence: 83%

Section: Methodsmentioning

confidence: 99%

Variable expression of extracellular polysaccharide in the marine bacterium Pseudomonas atlantica is controlled by genome rearrangement

Bartlett

Wright

Silverman

1988

Proc. Natl. Acad. Sci. U.S.A.

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“…Furthermore, by position effect analysis (7), Asheshov and Dykes concluded that the penicilhinase gene, originally located on the chromosome, was duplicated, with one copy being retained on the chromosome and the second being incorporated into the plasmid, and that both of the genes expressed their trait simultaneously. (202), has been observed with IS4 in gram-negative bacteria (97). Up to this time, among plasmids containing the 8-lactamase gene, precise physical genetic maps of plasmids pI258, pI524, and pI6187 of incompatibility group I and pII147 of group II VOL.…”

Section: Pathogenic Bacteriamentioning

confidence: 97%

Antibiotic resistance in pathogenic and producing bacteria, with special reference to beta-lactam antibiotics.

Ogawara¹

1981

Microbiological Reviews

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“…Secondly, excision could also account for the loss, as has been observed with other insertion elements (15). For instance, IS1mediated excision in E. coli removed more than 1 kb of flanking chromosome from either side of the element (34), while IS4 excision has been observed to delete chromosomal sequences from both sides of this element (24). Excision would typically involve the transposase of the insertion sequence and would not involve homologous recombination, so the losses here of intact DVR units would not be compatible with such a mechanism.…”

Section: Discussionmentioning

confidence: 99%

IS 6110 Transposition and Evolutionary Scenario of the Direct Repeat Locus in a Group of Closely Related Mycobacterium tuberculosis Strains

et al. 1998

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In recent years, various polymorphic loci and multicopy insertion elements have been discovered in the Mycobacterium tuberculosis genome, such as the direct repeat (DR) locus, the major polymorphic tandem repeats, the polymorphic GC-rich repetitive sequence, IS6110, and IS1081. These, especially IS6110 and the DR locus, have been widely used as genetic markers to differentiate M. tuberculosis isolates and will continue to be so used, due to the conserved nature of the genome ofM. tuberculosis. However, little is known about the processes involved in generating these or of their relative rates of change. Without an understanding of the biological characteristics of these genetic markers, it is difficult to use them to their full extent for understanding the population genetics and epidemiology of M. tuberculosis. To address these points, we identified a cluster of 7 isolates in a collection of 101 clinical isolates and investigated them with various polymorphic genetic markers, which indicated that they were highly related to each other. This cluster provided a model system for the study of IS6110 transposition, evolution at the DR locus, and the effects of these on the determination of evolutionary relationships among M. tuberculosis strains. Our results suggest that IS6110 restriction fragment length polymorphism patterns are useful in grouping closely related isolates together; however, they can be misleading if used for making inferences about the evolutionary relationships between closely related isolates. DNA sequence analysis of the DR loci of these isolates revealed an evolutionary scenario, which, complemented with the information from IS6110, allowed a reconstruction of the evolutionary steps and relationships among these closely related isolates. Loss of the IS6110 copy in the DR locus was noted, and the mechanisms of this loss are discussed.

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IS4 is still found at its chromosomal site after transposition to galT

Cited by 16 publications

References 23 publications

Variable expression of extracellular polysaccharide in the marine bacterium Pseudomonas atlantica is controlled by genome rearrangement

Variable expression of extracellular polysaccharide in the marine bacterium Pseudomonas atlantica is controlled by genome rearrangement

Antibiotic resistance in pathogenic and producing bacteria, with special reference to beta-lactam antibiotics.

IS 6110 Transposition and Evolutionary Scenario of the Direct Repeat Locus in a Group of Closely Related Mycobacterium tuberculosis Strains

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