Sequence analysis of plasmid pTF5, a 19.8-kb geographically widespread member of the Thiobacillus ferrooxidans pTFI91-like plasmid family.

The most important features of plasmid pTF5, a 19,793-bp plasmid that was isolated from Thiobacillus ferrooxidans ATCC33020, are presented. The plasmid contained at least 14 complete open reading frames (ORFs), most of which had clear amino acid sequence similarity to previously identified proteins. The majority of ORFs were related to proteins commonly found on plasmids such as replication-, partition-, and stability-associated proteins or on transposons such as transposases, an invertase, and a resolvase. Products of three of the ORFs were related to redox-active proteins and possibly constitute an electron transport system. Plasmids with restriction endonuclease maps identical to that of pTF5 have been widely reported among T. ferrooxidans strains, and in this study, pTF5 was itself shown to be a member of the widely distributed pTFI91 T. ferrooxidans plasmid family. A comparison of restriction endonuclease maps indicated that a pTFI91-like plasmid (9.8 kb) appeared to be contained entirely within pTF5.