Complete Nucleotide Sequence and Analysis of Two Conjugative Broad Host Range Plasmids from a Marine Microbial Biofilm

Abstract

The complete nucleotide sequence of plasmids pMCBF1 and pMCBF6 was determined and analyzed. pMCBF1 and pMCBF6 form a novel clade within the IncP-1 plasmid family designated IncP-1 ς. The plasmids were exogenously isolated earlier from a marine biofilm. pMCBF1 (62 689 base pairs; bp) and pMCBF6 (66 729 bp) have identical backbones, but differ in their mercury resistance transposons. pMCBF1 carries Tn5053 and pMCBF6 carries Tn5058. Both are flanked by 5 bp direct repeats, typical of replicative transposition. Both insertions are in the vicinity of a resolvase gene in the backbone, supporting the idea that both transposons are “res-site hunters” that preferably insert close to and use external resolvase functions. The similarity of the backbones indicates recent insertion of the two transposons and the ongoing dynamics of plasmid evolution in marine biofilms. Both plasmids also carry the insertion sequence ISPst1, albeit without flanking repeats. ISPs1is located in an unusual site within the control region of the plasmid. In contrast to most known IncP-1 plasmids the pMCBF1/pMCBF6 backbone has no insert between the replication initiation gene (trfA) and the vegetative replication origin (oriV). One pMCBF1/pMCBF6 block of about 2.5 kilo bases (kb) has no similarity with known sequences in the databases. Furthermore, insertion of three genes with similarity to the multidrug efflux pump operon mexEF and a gene from the NodT family of the tripartite multi-drug resistance-nodulation-division (RND) system in Pseudomonas aeruginosa was found. They do not seem to confer antibiotic resistance to the hosts of pMCBF1/pMCBF6, but the presence of RND on promiscuous plasmids may have serious implications for the spread of antibiotic multi-resistance.

Complete Genome Sequence of 3-Chlorobenzoate-Degrading Bacterium Cupriavidus necator NH9 and Reclassification of the Strains of the Genera Cupriavidus and Ralstonia Based on Phylogenetic and Whole-Genome Sequence Analyses

“…Therefore, the results of the current study support the previous classification of pENH91 as an IncP-1 plasmid. Five putative TrfA-binding sites (iterons) (Norberg et al, 2014) [(A/C/G)(A/C/T)GCCCC(C/T)CA(A/T)GTGTCA consensus sequences] were located between hypothetical protein-coding gene (BJN34_0385) and addiction module antitoxin-coding gene (BJN34_37215) (Figure S1C), suggesting that oriV was located in this region.…”

Environmentally co‐occurring mercury resistance plasmids are genetically and phenotypically diverse and confer variable context‐dependent fitness effects

“…Both pQBR44 and pQBR55 appear to have acquired mobile elements from the P. putida host used to isolate these plasmids during a relatively short period, and transposition can vary accessory genes between otherwise essentially identical plasmids (e.g. Eikmeyer et al, 2012;Norberg et al, 2014). Like other accessory genes, the genetic basis of mercury resistance is nested in a hierarchy of mobility: the mer operon is often associated with transposable elements, which in turn are often on mobilizable and conjugative elements such as plasmids (Norman et al, 2009;Partridge et al, 2009).…”

Roles of Extracellular Polysaccharides and Biofilm Formation in Heavy Metal Resistance of Rhizobia

“…A well-known and efficient mechanism of mercury resistance among Gram-positive and Gram-negative microorganisms (including S. meliloti ) [ 32 ] involves mercury reduction encoded by the microbial mer operon located on mobile genetic elements [ 33 , 34 ].…”