De. Rawlings et al., A MOLECULAR ANALYSIS OF A BROAD-HOST-RANGE PLASMID ISOLATED FROM THIOBACILLUS-FERROOXIDANS, FEMS microbiology reviews, 11(1-3), 1993, pp. 3-8
A 12.4-kb plasmid, pTF-FC2, that was isolated from Thiobacillus ferroo
xidans and which is capable of replication in a wide range of Gram-neg
ative bacteria, has been sequenced. The extent of the regions involved
in both replication and mobilization have been delineated. The site o
f initiation of replication (oriV) has been localized on a 185-bp frag
ment and the origin of transfer (oriT) on a 138-bp fragment. Three pro
teins that were essential for replication and four that were essential
for mobilization have been identified. The origin of replication was
clearly similar to that of the IncQ plasmids although no complementati
on or incompatibility between pTF-FC2 and the IncQ plasmid, R300B, was
detected. There was a clear similarity in the size, location and amin
o acid sequence of the proteins of the pTF-FC2 mobilization region wit
h those of the Tral region of the IncP plasmids, RP4 and R751. Two inv
erted repeated sequences which had 37/38-bp and 38/38-bp sequence iden
tity with the Tn21 transposon were identified. The C-terminal part of
a transposase and the N-terminal portion of a resolvase were located b
etween the inverted repeats. These open reading frames are most likely
the remnants of a defective transposon. A protein with homology to a
mercury-resistance regulator was also present within the transposon-li
ke element although no gene encoding for mercury reductase could be in
dentified.