title: IS Rm31, a new insertion sequence of the IS 66 family in Sinorhizobium meliloti.
abstract: Sinorhizobium meliloti natural populations show a high level of genetic polymorphism possibly due to the presence of mobile genetic elements such as insertion sequences (IS), transposons, and bacterial mobile introns. The analysis of the DNA sequence polymorphism of the nod region of S. meliloti p SymA megaplasmid in an Italian isolate led to the discovery of a new insertion sequence, IS Rm31. IS Rm31 is 2,803 bp long and has 22-bp-long terminal inverted repeat sequences, 8-bp direct repeat sequences generated by transposition, and three ORFs (A, B, C) coding for proteins of 124, 115, and 541 amino acids, respectively. ORF A and ORF C are significantly similar to members of the transposase family. Amino acid and nucleotide sequences indicate that IS Rm31 is a member of the IS 66 family. IS Rm31 sequences were found in 30.5% of the Italian strains analyzed, and were also present in several collection strains of the Rhizobiaceae family, including S. meliloti strain 1021. Alignment of targets sites in the genome of strains carrying IS Rm31 suggested that IS Rm31 inserts randomly into S. meliloti genomes. Moreover, analysis of IS Rm31 insertion sites revealed DNA sequences not present in the recently sequenced S. meliloti strain 1021 genome. In fact, IS Rm31 was in some cases linked to DNA fragments homologous to sequences found in other rhizobia species.
authors.affiliation: Dipartimento di Biologia animale e Genetica, via Romana 17, 50125, Florence, Italy.
authors.forename: Emanuele G
authors.initials: EG
authors.lastname: Biondi
authors.forename: Angelo Pietro
authors.initials: AP
authors.lastname: Femia
authors.forename: Filippo
authors.initials: F
authors.lastname: Favilli
authors.forename: Marco
authors.initials: M
authors.lastname: Bazzicalupo
mesh_terms: D001482:Base Composition; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D016680:Genome, Bacterial; D016366:Open Reading Frames; D010957:Plasmids; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D016962:Sinorhizobium meliloti / Q000235:genetics*; D020079:Terminal Repeat Sequences
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial