title: Novel miniature transposable elements in thermophilic Synechococcus strains and their impact on an environmental population.
abstract: The genomes of the two closely related freshwater thermophilic cyanobacteria Synechococcus sp. strain JA-3-3Ab and Synechococcus sp. strain JA-2-3B'a(2-13) each host several families of insertion sequences (ISSoc families) at various copy numbers, resulting in an overall high abundance of insertion sequences in the genomes. In addition to full-length copies, a large number of internal deletion variants have been identified. ISSoc2 has two variants (ISSoc2∂-1 and ISSoc2∂-2) that are observed to have multiple near-exact copies. Comparison of environmental metagenomic sequences to the Synechococcus genomes reveals novel placement of copies of ISSoc2, ISSoc2∂-1, and ISSoc2∂-2. Thus, ISSoc2∂-1 and ISSoc2∂-2 appear to be active nonautonomous mobile elements derived by internal deletion from ISSoc2. Insertion sites interrupting genes that are likely critical for cell viability were detected; however, most insertions either were intergenic or were within genes of unknown function. Most novel insertions detected in the metagenome were rare, suggesting a stringent selective environment. Evidence for mobility of internal deletion variants of other insertion sequences in these isolates suggests that this is a general mechanism for the formation of miniature insertion sequences.
authors.affiliation: Dana and David Dornsife College of Letters, Arts and Sciences, Department of Biological Sciences, Marine Environmental Division, University of Southern California, Wrigley Marine Science Center, Avalon, California, USA. wcnelson@usc.edu
authors.forename: William C
authors.initials: WC
authors.lastname: Nelson
authors.forename: Devaki
authors.initials: D
authors.lastname: Bhaya
authors.forename: John F
authors.initials: JF
authors.lastname: Heidelberg
mesh_terms: D001483:Base Sequence; D004251:DNA Transposable Elements / Q000235:genetics*; D004269:DNA, Bacterial; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D046940:Synechococcus / Q000378:metabolism*
chemical_list: D004251:DNA Transposable Elements; D004269:DNA, Bacterial