K. Maneewannakul et al., CONSTRUCTION OF DERIVATIVES OF THE F-PLASMID POX-TRA715 - CHARACTERIZATION OF TRAY AND TRAD MUTANTS THAT CAN BE COMPLEMENTED IN TRANS, Molecular microbiology, 22(2), 1996, pp. 197-205
A derivative of the F plasmid, pOX38-tra715, expresses the entire F tr
a operon from a foreign promoter (P-T7) derived from phage T7, A serie
s of plasmids related to pOX38-tra715 were constructed which carry eit
her deletion mutations or point mutations in traY. When the P-T7 promo
ter was induced, these plasmids expressed the F pilus but were transfe
r deficient unless TraY was supplied in trans from compatible plasmids
. Insertion of a kanamycin-resistance cassette in the traY gene of the
pOX38 plasmid, which contains the wild-type P-Y promoter, resulted in
loss of F piliation and transfer ability. Introduction of TraY in tra
ns partially restored piliation and transfer suggesting that TraY has
a role in positively regulating the P-Y promoter. pOX38-fra719-traD411
, which contains a chloramphenicol-resistance cassette in place of the
kanamycin-resistance cassette in pOX38-tra715 and a mutation in traD,
was constructed to demonstrate the utility of this series of plasmids
in studying the long (30 kb) F tra operon.