The insertion sequence element ISRm2011-2 belongs to the IS630-Tcl family of transposable elements and is abundant in Rhizobium meliloti

Selbitschka, Werner; Arnold, Walter; Jording, Doris; Kosier, Bob; Toro, Nicolás; Pühler, Alfred

doi:10.1016/0378-1119(95)00371-c

Cited by 33 publications

(28 citation statements)

References 17 publications

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“…At least two copies of ISRm1 (39) were found, one only of which is on the chromosome near the ntrB-ntrC operon on BAC27. ISRm2011-2, the only member of the IS630-Tc1/IS3 retroposon superfamily found in S. meliloti (40,41), was more widespread within the genome, with at least seven copies on the chromosome (BAC01, BAC03, BAC05, BAC18, BAC21, BAC22, and BAC25). ISRm3 (ISRm3-2) (42) was found in eight to nine copies on the genome, which is in keeping with previous studies, and we were able to identify three of these loci on the chromosome: near hsp70-recF site (BAC10), between ISRm1 and exoR (BAC27), and between ilvC and ftsZ2 (BAC35).…”

Section: Resultsmentioning

confidence: 99%

A high-density physical map of Sinorhizobium meliloti 1021 chromosome derived from bacterial artificial chromosome library

Capela¹,

Barloy-Hubler²,

Gatius³

et al. 1999

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

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Section: Resultsmentioning

confidence: 99%

A high-density physical map of Sinorhizobium meliloti 1021 chromosome derived from bacterial artificial chromosome library

Capela¹,

Barloy-Hubler²,

Gatius³

et al. 1999

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

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“…It is generally believed that insertion sequence (IS) elements in rhizobia promote genetic diversification through genomic rearrangements and recombination (8,11,17). The use of IS elements as probes for Southern hybridization can provide high-resolution fingerprints of rhizobial strains (26,27,31) and some information for understanding the function of these elements in rhizobial populations (2). An IS-related sequence, closely related to an Agrobacterium transposase from the widely studied plasmid pTiA6NC, has been found in the symbiotic region of R. galegae bv.…”

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confidence: 99%

Symbiotic and Genetic Diversity of Rhizobium galegae Isolates Collected from the Galega orientalis Gene Center in the Caucasus

Andronov

Terefework

Roumiantseva

et al. 2003

Appl Environ Microbiol

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This paper explores the relationship between the genetic diversity of rhizobia and the morphological diversity of their plant hosts. Rhizobium galegae strains were isolated from nodules of wild Galega orientalis and Galega officinalis in the Caucasus, the center of origin for G. orientalis. All 101 isolates were characterized by genomic amplified fragment length polymorphism fingerprinting and by PCR-restriction fragment length polymorphism (RFLP) of the rRNA intergenic spacer and of five parts of the symbiotic region adjacent to nod box sequences. By all criteria, the R. galegae bv. officinalis and R. galegae bv. orientalis strains form distinct clusters. The nod box regions are highly conserved among strains belonging to each of the two biovars but differ structurally to various degrees between the biovars. The findings suggest varying evolutionary pressures in different parts of the symbiotic genome of closely related R. galegae biovars. Sixteen R. galegae bv. orientalis strains harbored copies of the same insertion sequence element; all were isolated from a particular site and belonged to a limited range of chromosomal genotypes. In all analyses, the Caucasian R. galegae bv. orientalis strains were more diverse than R. galegae bv. officinalis strains, in accordance with the gene center theory.Rhizobium galegae (14) is a species that forms an effective symbiosis with plants of Galega orientalis and Galega officinalis, the only species in the genus Galega (Fabaceae) that have been studied for symbiosis. This symbiotic system represents a sharply defined cross-inoculation group. However, there are some differences in symbiotic performance. R. galegae strains are able to infect both Galega species, but strains isolated from G. officinalis form effective nodules on that plant and ineffective nodules on G. orientalis, while the converse is true for strains from G. orientalis (16). This finding, along with a wide range of phenotypic and genotypic approaches using numerical taxonomy (15), phage typing, DNA homology (13, 40), lipopolysaccharide and protein patterns (16), plasmid profiling (29), phylogeny of ribosomal genes (25, 35), randomly amplified polymorphic DNA, and repetitive PCR (21, 28), led to the proposal of two biovars for strains forming an effective symbiosis with G. officinalis (R. galegae bv. officinalis) and G. orientalis (R. galegae bv. orientalis) (24). Symbiosis-related genetic traits were found to be the main factor in genetic divergence between the biovars (24). G. orientalis is a good fodder plant with some widely used cultivars, whereas G. officinalis is rather poisonous because of its high alkaloid content and has no agricultural importance.The interesting symbiotic properties, together with the extensive taxonomic knowledge about R. galegae, prompted us to use the species to answer important questions related to the diversity and evolution of rhizobia and their symbiosis with legumes. A recent study indicated that R.galegae bv. orientalis strains have lower genetic diversity than R. galegae ...

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“…In natural conditions, the RmInt1 intron is found in the region encoding the transposase of an ISRm2011-2 insertion sequence (Selbitschka et al 1995;Martinez-Abarca et al 1998). Several stop codons in the sequence of the intron result in a premature end to the translation of the transposase gene, rendering intron splicing essential for the mobility of the insertion sequence in the host genome (MartinezAbarca et al 1998).…”

Section: Discussionmentioning

confidence: 99%

In vitro characterization of the splicing efficiency and fidelity of the RmInt1 group II intron as a means of controlling the dispersion of its host mobile element

Chillón

Molina-Sánchez

Fedorova

et al. 2014

RNA

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Group II introns are catalytic RNAs that are excised from their precursors in a protein-dependent manner in vivo. Certain group II introns can also react in a protein-independent manner under nonphysiological conditions in vitro. The efficiency and fidelity of the splicing reaction is crucial, to guarantee the correct formation and expression of the protein-coding mRNA. RmInt1 is an efficient mobile intron found within the ISRm2011-2 insertion sequence in the symbiotic bacterium Sinorhizobium meliloti. The RmInt1 intron self-splices in vitro, but this reaction generates side products due to a predicted cryptic IBS1 * sequence within the 3 ′ exon. We engineered an RmInt1 intron lacking the cryptic IBS1 * sequence, which improved the fidelity of the splicing reaction. However, atypical circular forms of similar electrophoretic mobility to the lariat intron were nevertheless observed. We analyzed a run of four cytidine residues at the 3 ′ splice site potentially responsible for a lack of fidelity at this site leading to the formation of circular intron forms. We showed that mutations of residues base-pairing in the tertiary EBS3-IBS3 interaction increased the efficiency and fidelity of the splicing reaction. Our results indicate that RmInt1 has developed strategies for decreasing its splicing efficiency and fidelity. RmInt1 makes use of unproductive splicing reactions to limit the transposition of the insertion sequence into which it inserts itself in its natural context, thereby preventing potentially harmful dispersion of ISRm2011-2 throughout the genome of its host.

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The insertion sequence element ISRm2011-2 belongs to the IS630-Tcl family of transposable elements and is abundant in Rhizobium meliloti

Cited by 33 publications

References 17 publications

A high-density physical map of Sinorhizobium meliloti 1021 chromosome derived from bacterial artificial chromosome library

A high-density physical map of Sinorhizobium meliloti 1021 chromosome derived from bacterial artificial chromosome library

Symbiotic and Genetic Diversity of Rhizobium galegae Isolates Collected from the Galega orientalis Gene Center in the Caucasus

In vitro characterization of the splicing efficiency and fidelity of the RmInt1 group II intron as a means of controlling the dispersion of its host mobile element

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