Identification and Distribution of Insertion Sequences of Paracoccus solventivorans

Abstract

ABSTRACT Three novel insertion sequences (ISs) (IS Pso1 , IS Pso2 , and IS Pso3 ) of the soil bacterium Paracoccus solventivorans DSM 11592 were identified by transposition into entrapment vector pMEC1. IS Pso1 (1,400 bp) carries one large open reading frame (ORF) encoding a putative basic protein (with a DDE motif conserved among transposases [Tnps] of elements belonging to the IS 256 family) with the highest levels of similarity with the hypothetical Tnps of Rhodospirillum rubrum and Sphingopyxis macrogoltabida . IS Pso2 (832 bp) appeared to be closely related to IS Ppa2 of Paracoccus pantotrophus DSM 11072 and IS 1248 of Paracoccus denitrificans PdX22, both of which belong to the IS 427 group (IS 5 family). These elements contain two overlapping ORFs and a putative frameshift motif (AAAAG) responsible for production of a putative transframe Tnp. IS Pso3 (1,286 bp) contains a single ORF, whose putative product showed homology with Tnps of ISs classified as members of a distinct subgroup of the IS 5 group of the IS 5 family. The highest levels of similarity were observed with IS Ssp126 of Sphingomonas sp. and IS 1169 of Bacteroides fragilis . Analysis of the distribution of ISs of P. solventivorans revealed that IS Pso2 -like elements are the most widely spread of the elements in nine species of the genus Paracoccus . IS Pso1 and IS Pso3 are present in only a few paracoccal strains, which suggests that they were acquired by lateral transfer. Phylogenetic analysis of Tnps of the novel ISs and their closest relatives showed their evolutionary relationships and possible directions of lateral transfer between various bacterial hosts.