title: Transposase-Mediated Excision, Conjugative Transfer, and Diversity of ICE6013Elements in Staphylococcus aureus.
abstract: ICE6013represents one of two families of integrative conjugative elements (ICEs) identified in the pan-genome of the human and animal pathogenStaphylococcus aureusHere we investigated the excision and conjugation functions of ICE6013and further characterized the diversity of this element. ICE6013excision was not significantly affected by growth, temperature, pH, or UV exposure and did not depend onrecAThe IS30-like DDE transposase (Tpase; encoded byorf1andorf2) of ICE6013must be uninterrupted for excision to occur, whereas disrupting three of the other open reading frames (ORFs) on the element significantly affects the level of excision. We demonstrate that ICE6013conjugatively transfers to differentS. aureusbackgrounds at frequencies approaching that of the conjugative plasmid pGO1. We found that excision is required for conjugation, that not allS. aureusbackgrounds are successful recipients, and that transconjugants acquire the ability to transfer ICE6013Sequencing of chromosomal integration sites in serially passaged transconjugants revealed a significant integration site preference for a 15-bp AT-rich palindromic consensus sequence, which surrounds the 3-bp target site that is duplicated upon integration. A sequence analysis of ICE6013from different host strains ofS. aureusand from eight other species of staphylococci identified seven divergent subfamilies of ICE6013that include sequences previously classified as a transposon, a plasmid, and various ICEs. In summary, these results indicate that the IS30-like Tpase functions as the ICE6013recombinase and that ICE6013represents a diverse family of mobile genetic elements that mediate conjugation in staphylococci.IMPORTANCEIntegrative conjugative elements (ICEs) encode the abilities to integrate into and excise from bacterial chromosomes and plasmids and mediate conjugation between bacteria. As agents of horizontal gene transfer, ICEs may affect bacterial evolution. ICE6013represents one of two known families of ICEs in the pathogenStaphylococcus aureus, but its core functions of excision and conjugation are not well studied. Here, we show that ICE6013depends on its IS30-like DDE transposase for excision, which is unique among ICEs, and we demonstrate the conjugative transfer and integration site preference of ICE6013A sequence analysis revealed that ICE6013has diverged into seven subfamilies that are dispersed among staphylococci.
authors.affiliation: Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson, Mississippi, USA.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Sansevere
authors.affiliation: Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson, Mississippi, USA.
authors.forename: Xiao
authors.initials: X
authors.lastname: Luo
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Joo Youn
authors.initials: JY
authors.lastname: Park
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Sunghyun
authors.initials: S
authors.lastname: Yoon
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Keun Seok
authors.identifier: http://orcid.org/0000-0001-9280-9680
authors.initials: KS
authors.lastname: Seo
authors.affiliation: Department of Microbiology and Immunology, University of Mississippi Medical Center, Jackson, Mississippi, USA darobinson@umc.edu.
authors.forename: D Ashley
authors.initials: DA
authors.lastname: Robinson
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003227:Conjugation, Genetic / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D014644:Genetic Variation; D000072417:Protein Domains; D013211:Staphylococcus aureus / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D019895:Transposases / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D019895:Transposases
keywords: Staphylococcus; Staphylococcus aureus; conjugation; gene transfer; mobile genetic elements