a transcription terminator signal necessary for plasmid colib-p9 replication.replication of the inci alpha plasmid colib-p9 requires the repz gene, which encodes an essential, unstable initiator protein termed repz. although many functional features of the colib-p9 replicon resemble those of structurally unrelated incfii plasmids r1 and nr1, the role of transcription of repz towards the replication origin is poorly understood. using a series of deletion and substitution mutants of the colib-p9 replicon, we found that repz prefers to act in cis and that a spacer sequence ...19957494478
evidence for two genetically distinct dna primase activities specified by plasmids of the b and i incompatibility groups.plasmid colib-p9 of the i alpha incompatibility group is known to encode a dna primase that acts in the conjugal transfer of the plasmid and can substitute for mutant dnag gene product in vegetative replication of the escherichia coli chromosome. the relevant genetic determinant (sog) has previously been cloned into a small multicopy vector plasmid. prototype incb plasmid r16 also suppresses host dnag mutations. the equivalent gene(s) (pri) of r16 was cloned into plasmid pbr325 and shown by filt ...19827045070
[organization of the genes responsible for colicin ib synthesis and immunity to it in plasmid colib-p9].to study the localization and expression of the colib-p9 plasmid genes responsible for colicin ib synthesis and immunity to it, we isolated a series of tn5 insertion mutants of recombinant plasmid piv41 containing the colicin ib gene in ecori fragment of colib-p9 (2.7 kb) and the deletion plasmid carrying only a part of the colicin gene. the direction of colicin ib gene transcription was determined by the analysis of the polypeptides synthesized in minicells carrying the mutant plasmids. the piv ...19852989085
[molecular cloning of plasmid colib-p9 genes responsible for its mutator function].the localization of plasmid colib-p9 muc genes mediating the plasmids protective and mutagenesis-increasing activity has been determined. the increase of muc genes dose by cloning them within the multicopy vector has been shown to repress the mutator function of the plasmid. no essential homology has been revealed between colib-p9 muc gene nucleotide sequences, pkm101 muc genes with a similar function, and umudc chromosome genes. it has been shown that the synthesis of 38 kd protein is essential ...19883062392
role of sog polypeptides specified by plasmid colib-p9 and their transfer between conjugating bacteria.the sog gene of the conjugative plasmid colib-p9 specifies two sequence-related polypeptides with the n-terminal third of the larger product having dna primase activity. to resolve the function of the c-terminal portion of the polypeptides, we constructed a colib mutant containing a tn5 insertion in the 3' region of sog. the mutation truncated sog gene products without inactivating dna primase and rendered the plasmid defective in conjugation. tests for the presence of conjugative pili, for comp ...19863024972
the ssb gene of plasmid colib-p9.the inci1 plasmid colib-p9 was found to carry a single-stranded dna-binding (ssb) protein gene (ssb) that maps about 11 kilobase pairs from the origin of transfer in the region transferred early during bacterial conjugation. the cloned gene was able to suppress the uv and temperature sensitivity of an ssb-1 strain of escherichia coli k-12. the nucleotide sequence of the colib ssb gene was determined, giving a predicted molecular weight of 19,110 for the ssb protein. sequence data show that colib ...19892651402
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