Biomedical subjects

M Konarska-Kozlowska

Publications and source records attributed to M Konarska-Kozlowska.

5 recordsLinked to original sources

PubMed1983

Sequence homology between Inc N group plasmids.

DNA-DNA hybridization combined with "Southern blotting" was used to analyse the genetic organization and the nucleotide sequence homology between different regions of a previously characterized Inc N group plasmid pCUI and nine other Inc N group plasmids. The following conclusions could be reached: (1) N plasmids isolated from different parts of the world share substantial DNA sequence homology and also some similarity of overall genetic organization, (2) the majority of the N plasmids used in this study showed conservation of distribution of BglII and KpnI cleavage sites. Often, restriction endonuclease fragments of similar electrophoretic mobility encoded the same genetic function, (3) in one case, the N-specific properties appear to be integrated into the bacterial chromosome. (4) the plasmid DNA in strains carrying two Inc N plasmids, R199 and R113 were each composed of two molecular species only one of which constituted an N group plasmid.

Base Sequence↗

PubMed1983

Inverted repeats in the DNA of plasmid pCU1.

Renaturable regions in the DNA strands of the N group plasmid pCU1 have been visualized as stem-loop structures by electron microscopy. Four such distinct structures are described, the smallest of which is within the loop of a larger one. The region of pCU1 in which these structures occur has several restriction sites. This and the availability of plasmid deletions and recombinants has permitted the mapping of these structures relative to one another and to the restriction and functional map of the plasmid. The replication and maintenance region of the plasmid is located within one of these stem-loop structures.

DNA, Bacterial↗

PubMed1983

Comparison of plasmids Co1E2-P9 and Co1E2-CA42 and their immunity proteins.

Plasmids ColE2-CA42 (6.1 kilobases) and ColE2-P9 (6.8 kilobases) were found to have homologous (4.3-kilobase) DNA segments which contain their colicin and immunity genes. The relatedness of their immunity proteins was verified by determining their amino acid compositions and N-terminal sequences. These characteristics were compared with those of ColE3-CA38.

Bacteriocin Plasmids↗

PubMed1981

Physical and genetic organization of the IncN-group plasmid pCU1.

A restriction endonuclease-cleavage map of the IncN group plasmid pCU1 was constructed. Deletion mutants of the plasmid were obtained by in vivo or in vitro methods. Comparison of the restriction maps of these mutants to that of pCU1 enables one to assign the known functions of the plasmid to particular regions on the plasmid DNA. For different enzymes, the number and distribution of restriction sites on pCU1 is compared to that of other IncN and related plasmids.

DNA Restriction Enzymes↗

PubMed1981

The genetic and physical basis of variability in Escherichia coli strains carrying a reference Inc N group plasmid.

The nature of basis of variability in the conjugational behaviour of RM98+ (RM98-carrying) strains of Escherichia coli K-12 that are otherwise similar in phenotype was studied. An explanation for such variability is provided. Some RM98+ strains of E. coli have a plasmid aggregate, which upon conjugation yields two different conjugative plasmids. The first (pCU1) is an N conjugative group plasmid by all available criteria. The second (pCU2) could not be placed in any conjugative group known among the Enterobacteriaceae. Reciprocal DNA hybridization experiments and the gel patterns displayed by the two plasmid DNAs upon digestion with different restriction endonucleases indicate no extensive sequence homology between pCU1 and pCU2. PCU2 DNA is much longer than pCU1 DNA. Despite the absence of extensive homology, the DNA of pCU1 and pCU2 can interact. Derivatives can be selected that have all the antibiotic markers of the aggregate plasmid but that neither contain nor segregate pCU2. It is shown that in such strains a DNA fragment of molecular weight 7.9 X 10(6) has been added to pCU1 concurrently with a tetracycline resistance marker originally present in pCU2 and absent in pCU1. These observations suggest that tetracycline resistance in pCU2 may be part of a large translocatable element. RM98 has been used to designate a reference Inc N group plasmid. The results presented indicate that this can lead to ambiguity. pCU1 would now be the appropriate reference plasmid.

Anti-Bacterial Agents↗