Fertility repression of F-like conjugative plasmids: Physical mapping of the R6-5 finO and finP cistrons and identification of the finO protein

Abstract

The locations of the fertility inhibition genes finO and finP of the F-like conjugative multiple antibioticresistance plasmid R6-5 have been determined. As found previously for that of the fertility plasmid F, the finPgene of R6-5 is located close to the origin of DNA transfer, oMT, and to the promoter-proximal segment of the tra operon. Thus, finP is close to the site of action of the FinOP fertility inhibition system. In contrast, the finO gene is located on the other side of the tra operon, greater than 35 kilobases from the finP gene; finO is very close to the origin of vegetative replication, oriV, and to cistrons encoding functions involved in autonomous plasmid replication and plasmid incompatibility. A 4.5-kilobase fragment of R6-5 DNA containing the finO gene has been cloned on the high-copy amplifiable vector plasmid pBR322. This hybrid plasmid, desigated pKTO31, causes severe repression of conjugal transfer of plasmid F, indicating the production of high cellular levels of finO protein. Two indepndent fino mutant derivatives were obtained after mutagenesis of the pKTO3l plasmid. Comparison of proteins synthesized by minicells carrying finO mutant plasmids with those carrying various finO+ plasmids enables the finO gene product to be tentatively identified as a 22,000-dalton protein.

Complete DNA Sequence of a ColBM Plasmid from Avian Pathogenic Escherichia coli Suggests that It Evolved from Closely Related ColV Virulence Plasmids

“…Also found within this region were sok and mok, involved in postsegregational killing to ensure plasmid stability (46). Downstream of the traX gene was finO, a fertility inhibition gene (47), srnB, a modulator of postsegregational killing (13), and a putative toxin-antitoxin plasmid stability system. Downstream of the transfer region was one of the two plasmid replicons of pAPEC-O1-ColBM.…”

Nucleotide sequences of five IncF plasmid finP alleles

“…There may be two types offinO products, differentiated by their various abilities to inhibit this transfer (22). ThefinO genes from plasmids R100 and R6-5 have been cloned, but the finO product remains undefined (2,3,18).The finP gene is located between traM and traJ (8), and the nucleotide sequence of this region from the F plasmid has been determined (17). Mullineaux and Willetts (11) suggested that finP is transcribed from a potential promoter within the translated region of the traJ transcript and that it is transcribed in the opposite direction from traJ transcription.…”

“…There may be two types offinO products, differentiated by their various abilities to inhibit this transfer (22). ThefinO genes from plasmids R100 and R6-5 have been cloned, but the finO product remains undefined (2,3,18).…”

Cloning, mapping, and sequencing of plasmid R100 traM and finP genes

“…By using these sizes and a value of 87.2 for the R100 coordinate of the EcoRI B-H fragment junction, as determined by sequencing (37), and the assigned value of 89.3 for the ISMb resistance determinant reference point (29), the EcoRI D-C fragment junction was located at 49.4 kilobases. The EcoRI D fragment of plasmid R100 (R100-1) contains the oriT, traM, finP, and traJ genes and the first part of the tra YZ operon (46) in addition to ISIOR and a portion of the tet gene of TnlO. The DNA sequences for ISIOR (15) and the tet gene (17,33) are known and were used to identify restriction sites in the right half of this fragment.…”

“…The traJ and finP genes from both R100 and the F factor are plasmid specific, but the finP genes of other IncFII plasmids such as R136 and R6-5 appear identical to the finP gene of R100 (9,46). Sex factor F does not have a functional finO gene, but the product of the finO gene of R100 is able to function fully with its own genes and with those of sex factor F to control transfer of both plasmids.…”