title: Analysis of insertion sequences in thermophilic cyanobacteria: exploring the mechanisms of establishing, maintaining, and withstanding high insertion sequence abundance.
abstract: Insertion sequences (ISs) are simple mobile genetic elements capable of relocating within a genome. Through this transposition activity, they are known to create mutations which are mostly deleterious to the cell, although occasionally they are beneficial. Two closely related isolates of thermophilic Synechococcus species from hot spring microbial mats are known to harbor a large number of diverse ISs. To explore the mechanism of IS acquisition within natural populations and survival in the face of high IS abundance, we examined IS content and location in natural populations of Synechococcus by comparing metagenomic data to the genomes of fully sequenced cultured isolates. The observed IS distribution in the metagenome was equivalent to the distribution in the isolates, indicating that the cultured isolates are appropriate models for the environmental population. High sequence conservation between IS families shared between the two isolates suggests that ISs are able to move between individuals within populations and between species via lateral gene transfer, consistent with models for IS family accumulation. Most IS families show evidence of recent activity, and interruption of critical genes in some individuals was observed, demonstrating that transposition is an ongoing mutational force in the populations.
authors.affiliation: College of Letters, Arts & Sciences, Department of Biological Sciences, Marine Environmental Biology Division, University of Southern California, Wrigley Marine Science Center, P.O. Box 5069, Avalon, CA 90704-5069, USA. wcnelson@usc.edu
authors.forename: William C
authors.initials: WC
authors.lastname: Nelson
authors.forename: Lori
authors.initials: L
authors.lastname: Wollerman
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*; D022761:Gene Transfer, Horizontal / Q000235:genetics*; D014644:Genetic Variation; D016678:Genome; D016680:Genome, Bacterial; D045482:Hot Springs / Q000382:microbiology; D056186:Metagenomics; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D046940:Synechococcus / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004251:DNA Transposable Elements