We isolated a series of Tn5-insertional mutants from the mini-F plasmid, which has a deletion in the origin II region and replicates exclusively from origin 1, and found that the mutants that had Tn5 in either the F4 or the F5 gene were defective in their replication. It is concluded that, in additi
An essential gene for replication of the mini-F plasmid from origin I
β Scribed by Tanimoto, Kouichi ;Iino, Tetsuo
- Publisher
- Springer
- Year
- 1984
- Tongue
- English
- Weight
- 551 KB
- Volume
- 196
- Category
- Article
- ISSN
- 0026-8925
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β¦ Synopsis
We constructed a series of defective mini-F plasmids, which have deletion(s) in the replication origin I and/or origin II, and their derivatives, which do not produce F3 protein, by insertion of the XhoI fragment of Tn5 into the XhoI site at 41.0 F (kilobases on the coordinate map of F-plasmid). Using these mutant mini-F plasmids, we found that F3 protein is essential for the replication of mini-F from origin I, but not from origin II.
π SIMILAR VOLUMES
At the XhoI site (45.08F) of plasmid mini-F a deletion of 649 bp was generated employing exonuclease Bal31. By this deletion nucleotide sequences functioning as origin II and the four 19 bp direct repeats constituting the incB region in front of the E protein gene were removed from the plasmid. Anal
DNA sequencing'shows that the mutational alteration resulting from an amber-suppressible replicationdefective mutation of F plasmid is a single base pair change from C:G to T:A which yields an amber codon in the coding frame for a 29 kd polypeptide located in the minimal replication region. We thus