Plasmid 58 (2007) 31–43 www.elsevier.com/locate/yplas 0147-619X/$ - see front matter  2006 Elsevier Inc. All rights reserved. doi:10.1016/j.plasmid.2006.11.007 The multiple antibiotic resistance IncP-1 plasmid pKJK5 isolated from a soil environment is phylogenetically divergent from members of the previously established ,  and  sub-groups Martin Iain Bahl a , Lars Hestbjerg Hansen a , Alexander Goesmann b , Søren J. Sørensen a,¤ a Department of Microbiology, University of Copenhagen, Sølvgade 83H, 1307 Copenhagen K, Denmark b Bielefeld University, Center for Biotechnology (CeBiTec), D-33594 Bielefeld, Germany Received 29 June 2006, revised 7 November 2006 Available online 16 February 2007 Communicated by A. Mark Osborn Abstract The 54,383bp plasmid pKJK5 was recovered from a soil environment by exogenous plasmid isolation and conveys resis- tance towards tetracycline and trimethoprim. Sequencing and annotation revealed a high level of structural similarity of the backbone genes to other IncP-1 plasmids containing a Tra1 and Tra2 region, a central control module and a replication initia- tion module. A considerable degree of divergence was associated with the backbone genes of pKJK5 as compared to homolo- gous genes in the ,  and  subgroups, which indicates that pKJK5 may belong to a novel subgroup of IncP-1 plasmids, which may also accommodate the partially sequenced non-subgroup classiWed plasmid pEMT3. Individual backbone genes in pKJK5 have a GC-content, which is consistently lower (average 6.3%) than the homologous genes from the archetype IncP-1 plasmid R751 indicating homogenous amelioration of IncP-1 plasmid backbone genes. Two discrete accessory elements of 2145 bp (load 1) and 11678 bp (load 2) respectively are situated between the Tra1 and Tra2 regions of pKJK5, both bounded by inverted repeats and direct Xanking repeats indicative of transposon-mediated insertion. Load 1 consists of an insertion sequence ISPa17 and load 2 is a Tn402-derivative containing a class 1 integron, IS1326 and a fragment identical to a region of plasmid pTB11 harboring a tetracycline resistance determinant and part of an IncP-1 oriV region.  2006 Elsevier Inc. All rights reserved. Keywords: Plasmid; IncP-1; Transposable element; Integron; Antibiotic resistance 1. Introduction During the past few decades it has become increasingly apparent that extra-chromosomal plas- mids contribute immensely to the phenotypic diver- sity of bacterial communities in environmental settings (Smit et al., 1998; Droge et al., 2000; Berg- strom et al., 2004; Hansen et al., 2004). Extensive anthropogenic use of antibiotics in clinical settings, aquaculture and farming has drastically increased the selective pressure of these compounds and * Corresponding author. Fax: +45 35 32 20 40. E-mail address: sjs@bi.ku.dk (S.J. Sørensen).