Nucleotide sequences of five IncF plasmid finP alleles

Abstract

The nucleotide sequences of fivefinP alleles from various IncF plasmids (finP types I to V) as well as of three finP mutations were determined and compared. ThefinP gene specificity could be attributed to a variable, sixto-seven-nucleotide loop located between inverted repeats, and the sequence data were consistent with the product offinP being an RNA molecule rather than a protein. ThefinP mutations interrupted a proposedfinP promoter or destabilized a predicted stem-and-loop structure in the finP RNA molecule.Conjugal DNA transfer requires expression of the transfer (tra) operon which is regulated in a two-stage process involving the fertility inhibition system (finO and finP) and the traJ gene (4, 5). The products offinO and finP (FinO and FinP) are regulatory elements that act together at the fisO site (otherwise designated Oj or traO) to prevent traJ transcription. The traJ gene product, a positive control element, interacts with the pyz promoter, increasing transcription of the tra YZ operon (6,11,21).All finO products from IncF plasmids studied to date are capable of complementing the naturalfinO mutation of the F plasmid (22) and inhibiting its transfer. 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.FinP is plasmid specific, since six finP alleles were found among the 12 IncF plasmids studied (22 (11,22). Wild-type finP regions of types II to V (22) from the IncF plasmids R124, ColVBtrp, R1-19, R100-1, and ColB4 were cloned, sequenced, and compared with the sequence of the finP region of the F plasmid (type I) (Fig. 1). In addition, the sequences of three finP mutations, plasmid pED236 (ColB2Fdr, type II), plasmid pED200 (R124 finP, type II), and plasmid pED202 (R386finP, type VI, or R386fisO, type VI, or both), which lead to derepression of the transfer operon in these plasmids were determined (Fig. 1) The finP promoter was located within a BglII-TaqI fragment in F corresponding to positions 1 to 84 in Fig. 1 (11) and may overlap the BamHI site at position 35 in R100-1 (type IV) (B. E. Fee and W. B. Dempsey, submitted for publication). It is evident that the -35 and -10 regions of a putative promoter are highly conserved in all the finP alleles examined (positions 10 to 38). Except for position 15, the -35 region of this finP promoter matches the procaryotic consensus sequence TTGACa (7). The sequence at the proposed -10 region is conserved in four of the five alleles; only R100-1 differs at position 35. This sequence also strongly resembles the proposed consensus sequence for...

Regulation of finP Transcription by DNA Adenine Methylation in the Virulence Plasmid of Salmonella enterica

“…The GGTC mutation produced an inactive finP promoter (data not shown). The latter observation is in agreement with data reported for other F-like plasmids (16,30).…”

“…The GGTC mutation produced an inactive finP promoter (data not shown). The latter observation is in agreement with data reported for other F-like plasmids (16,30).The failure of GATC3GATG and GATC3GCTC mutations to make finP transcription Dam independent was further supported by their effects on the expression of a traJ::lac translational fusion (Table 3). Neither mutation altered the expression pattern typical of the traJ::lac fusion (always higher in a …”

Identification and characterization of the products from the traJ and traY genes of plasmid R100

“…(B) The strategy used to determine the nucleotide sequence of the region carried by pS187-ES3 is shown by arrows. The nucleotide sequences in the two regions containing finP and traA of R100 were identical to those of its derivative, R100-1, which have been previously reported (10,14). McIntire and Dempsey (29) have reported the nucleotide sequence containing oriT, which shows the following differences from ours: A at position 7 in McIntire and Dempsey (29) was G in our sequence; T at position 8 was C; T at 12 was C; C at 377 was T; G at 510 was A.…”

Genetic and nucleotide sequence analysis of the gene htdA, which regulates conjugal transfer of IncHI plasmids

“…The methodology used in this study selected only for derepressed derivatives, and therefore the possibility exists that other transpositions in this region can abolish transfer. In the IncF plasmid system, most of the transfer genes are encoded by one transcript, whose transcription is both positively and negatively regulated by several components (12,16,17,30). One of these genes, finO, produces a 22-kDa protein which is required for full repression of IncF transfer (13,37).…”