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PubMed1994

Lack of correlation between the presence of 70 kb plasmid and plasmid-associated determinants of Yersinia enterocolitica.

The relatedness between the plasmids from Yersinia enterocolitica 0:4.32 and 0.9 was examined. Plasmid 0:4.32 was found in many clinical isolates of Y. enterocolitica and was related to pYV plasmid of Y. enterocolitica 0:9. The homology between the plasmid and chromosomal DNAs of strains 0:4.32 and 0:9 was examined. The Ca(2+)-dependent expression of the OmpF and OmpC proteins is described.

Animals↗
PubMed1993

Characteristics and significance of DNA binding activity of plasmid stabilization protein ParD from the broad host-range plasmid RK2.

A region of the plasmid RK2 has been shown to stabilize plasmid replicons in a broad host-range manner. This region encodes two divergently transcribed operons: parCBA and parDE. The parCBA operon specifies a multimer resolution system, while the parDE operon alone is capable of stabilizing an RK2-derived minireplicon under defined growth conditions in several different Gram-negative bacteria. The observed autoregulation of the parDE operon is most likely the result of ParD protein binding within the PparDE region. The characteristics of ParD binding to this region and the role of such binding in plasmid stabilization were examined with purified ParD protein. The results indicate that the binding of a single dimer of ParD protein to the promoter region most likely blocks interaction of RNA polymerase holoenzyme with the promoter. DNase I protection experiments indicate that ParD binds to a discrete sequence of 48 base pairs in length. While the binding of ParD to PparDE is essential for proper regulation of expression of the ParD and ParE proteins in vivo, the analyses of binding properties of mutant ParD proteins suggest that binding to this region does not play a direct role in plasmid stabilization.

Amino Acid Sequence↗
PubMed1993

[The role of phospholipids and their fatty acids in the structural organization of membranes of plasmid-containing and plasmid-less Salmonella derby cells].

The effect of R-plasmid on the qualitative and quantitative compositions of phospholipids and their fatty acids in bacterial (S. derby) cells has been studied. It has been found that the lack of R-plasmid in bacterial cells leads to a sharp decrease in the phospholipid content, in the phosphatidylcholine content in particular, and causes an increase in the per cent content of lysophosphatidylcholines. The per cent content of saturated and nonsaturated fatty acids of phospholipids in plasmid-free cells does not change appreciably. In the plasmid-free strain of S. derby the intensity of lipid peroxidation is associated with a relatively high content of alpha-tocopherol.

Cell Membrane↗
PubMed1977

Replication of Fpoh+ plasmid in mafA mutants of Escherichia coli defective in plasmid maintenance.

A class of F' plasmids, designated Fpoh+, was previously shown to be able to replicate extra-chromosomally on Hfr strains by virtue of carrying the specific site or region poh+ (permissive on Hfr) of the E. coli chromosome (Hiraga, 1975, 1976a). These plasmids were now found to replicate on E. coli mafA mutants (mafA1 and mafA23) that cannot support vegetative replication of F and some other F-like plasmids. The derivatives of Fpoh+ that have lost the poh+ site, on the other hand, failed to replicate on mafA mutants. These mutants harboring Fpoh+ (but not Poh- derivatives thereof) exhibit abnormal cell division and form elongated cells, presumably due to competition between Fpoh+ and the host chromosome for some factor(s) essential for the initiation of DNA replication of the both replicons. It is tentatively concluded that the poh+ site is required for F' plasmids to replicate on mafA mutants as well as on Hfr strains. In view of the fact that the mechanism of inhibition of autonomous F DNA replication in mafA mutants and in Hfr strains are clearly different, the present data seem to provide strong support to the notion that the poh+ region contains the replication origin of the E. coli chromosome.

Conjugation, Genetic↗
PubMed1988

The F factor of Escherichia coli carries a locus of stable plasmid inheritance stm, similar to the parB locus of plasmid RI.

We found that a 1.4 kb fragment of the F factor of Escherichia coli (coordinates 62.8-64.2) considerably increased the stable inheritance of different plasmids which carried it. The fragment has a 589 bp DNA sequence (coordinates 63.3-63.9) with extensive homology to the parB locus of plasmid RI and, probably like the parB region, ensures the presence of plasmids in bacterial populations by killing those cells which have lost the plasmid.

Base Sequence↗
PubMed1982

Analysis of plasmid genome evolution based on nucleotide-sequence comparison of two related plasmids of Escherichia coli.

Plasmid Rsc13, a small derivative of the plasmid R1, contains a region necessary for replication as well as a complete copy (4957 bp) of the ampicillin resistance transposon, Tn3. We determined the nucleotide sequence of the replication region of Rsc13 to be 2937 bp and then compared this region (designated the 2.9-kb region) to the analogous region of pSM1, a small derivative of the plasmid R100 which has common ancestry with R1. Rsc13 and pSM1 were 96% homologous in this 2.9-kb region except for a discrete region of about 250 bp which showed only 44% homology. The sequence and distribution of nucleotide substitutions between Rsc13 and pSM1 supported a map of possible genes and sites which have previously been seen in the replication region of Rsc13 and pSM1 which showed only 44% homology. Analysis of the amino acid sequence and predicted conformation of the two RepA2 polypeptides, however, suggested that they were very similar. We proposed that the repA2 region of R1 and R100 was replaced by a substitution of a short DNA segment from another plasmid which was evolutionarily related to R1 and R100 but had more divergence. This event may have been mediated by a mechanism similar to that of gene conversion as described in eukaryotic systems.

Ampicillin↗
PubMed1973

Temperature-sensitive mutants for the replication of plasmids in Escherichia coli. II. Properties of host and plasmid mutations.

Host mutations in Escherichia coli K12 selected for the temperature-sensitive replication of the bacterial plasmid colicinogenic factor E(1) (ColE(1)) exhibit a pleiotropic effect with respect to the effect of the mutation on other extra-chromosomal elements. The mutations also vary with respect to the time of incubation of the cells at 43 degrees C required for complete cessation of ColE(1) DNA synthesis. While the synthesis of the bacterial chromosome appears unaffected, supercoiled ColE(1) DNA replication stops immediately in some mutants and gradually decreases during several generations of cell growth before stopping in others. Mutations isolated in the ColE(1) plasmid resulted in only a gradual cessation of ColE(1) DNA synthesis over several generations of cell growth at 43 degrees C. Conjugal transfer of the ColE(1) and ColV factors occurs normally in the host mutants when the transfer is carried out at the permissive temperature; however, the presence of a group I mutation in the donor cell prohibited conjugal transfer of either plasmid DNA at 43 degrees C to a normal recipient cell. Similarly, the presence of this mutation in the recipient prevented the establishment of ColE(1) or ColV in the mutant recipient cell upon conjugation with a normal donor at 43 degrees C. Various host ColE(1) replication mutants carrying either ColE(1) or ColE(2) were also defective in the mitomycin C-induced production of colicin E(1) or colicin E(2) at 43 degrees C. The majority of the host mutations examined exhibited a temperature sensitivity to growth in deoxycholate in addition to the inhibition of plasmid DNA replication, suggesting a membrane alteration in these mutants when grown at the restrictive temperature.

Coliphages↗
PubMed1981

Antibiotic resistance and R-plasmids in food chain Salmonella: evidence of plasmid relatedness.

A large number of strains (1,783) belonging to 15 Salmonella serovars isolated, in Canada, from the three major links of the human food chain were screened for multiple antibiotic resistance and the presence of R-plasmids. Multiresistant strains occurred among animal feed, livestock, and human isolates at frequencies of 4, 22, and 14%, respectively. Conjugation analysis revealed that 58% of the isolates from feeds, 87% of those from livestock, and 89% of the human strains carried all or part of their resistance determinants extrachromosomally on R-plasmids. Conjugative plasmids representing nine different incompatibility groups were detected, with the Inc I alpha group being predominant. Within the limits of the parameters measured, certain of these plasmids show a degree of relatedness suggestive of a common ancestry.

Anti-Bacterial Agents↗
PubMed1973

Plasmid in Bacillus pumilus and the enhanced sporulation of plasmid-negative variants.

Approximately 3% of the deoxyribonucleic acid (DNA) of Bacillus pumilus NRS576 can be isolated as covalently closed, circular duplex molecules of homogeneous size. The mol wt of the 576 plasmid is approximately 30 million. NRS576 (plasmid(+)) is oligosporogenic; less than 1% of the cells form spores during incubation in liquid AK sporulation medium. Variants that form spores at a high frequency (greater than 50% spores in 24 h) occur spontaneously at a frequency of approximately 10(-5). More than 25 such variants have been examined and all lack detectable plasmid DNA. A relationship appears to exist between the oligosporogenic properties of NRS576 and the presence of the 576 plasmid.

Bacillus↗
PubMed1974

Characterization of three plasmid deoxyribonucleic acid molecules in a strain of Streptococcus faecalis: identification of a plasmid determining erythromycin resistance.

Three plasmids designated alpha, beta, and gamma, distinguishable by their molecular weights (6, 17, and 34 million, respectively) were isolated from Streptococcus faecalis strain DS-5 (ATCC 14508). Derivatives of this strain "cured" for erythromycin resistance lacked the beta-plasmid. In the parent strain the beta-plasmid was estimated to be present to the extent of one to two copies per chromosomal genome equivalent whereas the alpha- and gamma-plasmids were about nine and five copies, respectively.

Acridines↗
PubMed1975

Polynucleotide sequence relationships among Ent plasmids and the relationship between Ent and other plasmids.

Deoxyribonucleic acid-deoxyribonucleic acid hybridization studies reveal that the plasmids coding for the production of heat stable and heat labile enteroxtoxins of Escherichia coli, regardless of their origin, have a majority of their polynucleotide sequences in common, but are not related in any significant way to those plasmids coding for the synthesis of only ST toxin. The heat stable and heat labile plasmids also share a significant degree of their polynucleotide sequences with plasmids of the FI and FII incompatibility groups, but not with R factors belonging to the I, N, W, P, or X incompatibility groups.

Animals↗
PubMed1976

Electron microscope study of a plasmid chimera containing the replication region of the Escherichia coli F plasmid.

pML31, a plasmid chimera constructed to contain the replication genes of an Flac plasmid, has been studied by electron microscope methods. Heteroduplex analysis shows that the only F sequence present in pML31 is that with corrdinates 40.3-49.3F. This region has previously been identified as essential for plasmid maintenance. The sequence of pML31, which was derived originally from R6-5, carries the km gene(s) and an inverted duplication of a 1.0-kilobase sequence. On the basis of length measurements, the repeated sequence is different from IS1, IS2, IS3, and an inverted repeat associated with the km gene(s) of plasmid JR67.

Base Sequence↗
PubMed1978

Viral R plasmid Rphi6P: properties of the penicillinase plasmid prophage and the supercoiled, circular encapsidated genome.

Properties of the viral R plasmid Rphi6P are described. As a temperate bacteriophage, it plaques on the facultative phototroph Rhodopseudomonas sphaeroides. Under aerobic conditions the phage had a latent period of 180 min, a burst time of 200 min, and a burst size of 15 to 20 particles per infective center. The encapsidated viral genome occurred as a supercoiled, circular DNA duplex with a mean contour length of 16.5 +/- 10 micron. Percent guanine plus cytosine, as calculated from thermal denaturation profiles, was 63.5. Mitomycin C-induced loss of the prophage suggested an extrachromosomal location in the host cell. Use of this curing agent enabled the isolation of a plasmid-free strain of R. sphaeroides. Biophysical analysis of the plasmid-free strain lysogenized with Rphi6P confirmed that the prophage occurred as a plasmid in the host cell.

Adsorption↗
PubMed1985

Some mercurial resistance plasmids from different incompatibility groups specify merR regulatory functions that both repress and induce the mer operon of plasmid R100.

Transcription of the mer genes of plasmid R100 is regulated by the product of the merR gene. The merR gene negatively regulates its own expression and also controls the transcription of the merTCA operon both negatively (in the absence of inducer) and positively (in the presence of inducer). We used transcriptional mer-lac fusions of R100-1 in complementation tests to measure the ability of the merR products of different mercury-resistant transposons and plasmids to functionally interact with R100-1. Plasmids from incompatibility groups C, B, S, L, and P, as well as the Pseudomonas transposons Tn501 and Tn3401, regulated the expression of the R100 mer genes in a similar fashion to the R100-1 merR product itself, suggesting that these elements are closely related. Only plasmid R391 (IncJ) did not complement.

DNA, Recombinant↗
PubMed1986

Nucleotide sequence of the constitutive macrolide-lincosamide-streptogramin B resistance plasmid pNE131 from Staphylococcus epidermidis and homologies with Staphylococcus aureus plasmids pE194 and pSN2.

The complete nucleotide sequence of the Staphylococcus epidermidis plasmid pNE131 is presented. The plasmid is 2,355 base pairs long and contains two major open reading frames. A comparison of the pNE131 DNA sequence with the published DNA sequences of five Staphylococcus aureus plasmids revealed strong regional homologies with two of them, pE194 and pSN2. The region of pNE131 containing the reading frame which encodes the constitutive ermM gene is almost identical to the inducible ermC gene region of pE194, except for a 107-base-pair deletion which removes the mRNA leader sequence required for inducible expression. A second region of pNE131 contains an open reading frame with homology to the small cryptic plasmid pSN2 and potentially encodes a 162-amino-acid protein.

Amino Acid Sequence↗
PubMed1997

Chemical analysis of poly-gamma-glutamic acid produced by plasmid-free Bacillus subtilis (natto): Evidence that plasmids are not involved in poly-gamma-glutamic acid production.

It has been postulated that the psf gene on a small plasmid, pUH1 (5.8 kb), regulates positively the synthesis of capsular poly-gamma-glutamic acid (gammaPGA) in Bacillus subtilis (natto) Asahikawa. We found that this strain harbored a second plasmid, named pNAGL1 (ca. 50 kb), in addition to pUH1. The growth conditions that cure pUH1 or pNAGL1 were established. The plasmid-free NAF4 strain derived from B. subtilis (natto) Asahikawa was found to produce gammaPGA which was the same as the parent strain in terms of quantity and chemical properties having the same molecular mass and content of D-glutamic acid. Furthermore, as in the case of the parent cells, the D-glutamic acid in gammaPGA, which is known to increase up to ca. 80% of the total glutamic acid as Mn(2+) ion concentration increases in growth medium, was found to make up 80% of the total glutamic acid of the gammaPGA produced by NAF4 cells grown in the presence of 0.1 mm MnCl(2). Thus, these results led us to conclude that the plasmids do not encode any gene important for gammaPGA production.

Journal Article↗
PubMedDate not supplied

Characterisation of the ColE8 plasmid, a new member of the group E colicin plasmids.

We have determined the restriction map of the ColE8-J plasmid after cloning it into the pBR322 vector. By subcloning and transposon mutagenesis we have localized the colicin immunity gene, the colicin structural gene, and lys, the region that determines MC sensitivity. In contrast to the ColE3-CA38 plasmid, the genes coding for colicin E8 production and immunity cannot be cloned on a single EcoRI fragment. Insertion of Tn5 transposons into the colicin structural gene region of the recombinant plasmid inactivated colicin production and MC sensitivity. Insertion of transposons into the lys region reduced colicin E8 production and MC induced lysis, the extent of which was dependent upon the precise site of insertion. We propose that the colicin E8 structural gene and lys must be transcribed from a common promoter situated proximal to the structural gene, whilst the colicin E8 immunity gene is transcribed from a second promoter. The lys region is responsible both for cell lysis after MC induction and positive regulation of colicin E8 synthesis.

Bacteriocin Plasmids↗
PubMed1996

An unusually long-lived antisense RNA in plasmid copy number control: in vivo RNAs encoded by the streptococcal plasmid pIP501.

The main regulator of pIP501 replication is an antisense RNA (RNAIII) that induces transcriptional attenuation of the essential RNAII. Previous studies identified the termination point in vivo and demonstrated attenuation in vitro. This in vivo analysis confirms the appearance of attenuated RNAII dependent on RNAIII. Half-lives and intracellular levels of RNAII and RNAIII were determined: in a Bacillus subtilis cell harboring a wild-type pIP501 plasmid, approximately 50 molecules RNAII and 1000 to 2000 molecules of RNAIII were measured, respectively. The half-life of RNAII was in the range of that of other target RNAs, whereas that of RNAIII (approximately 30 minutes) was unusually long, representing a so far unprecedented case of a metabolically stable antisense RNA regulating plasmid copy number. Long antisense RNA half-life is predicted to yield sluggish control and instability of maintenance. We propose a model for how plasmid pIP501 may avoid this problem by using both the repressor CopR and the antisense RNAIII for control. Four stem-loop mutants of RNAII/RNAIII with elevated copy numbers were characterized for in vitro antisense/target RNA binding, RNAIII half-life, incompatibility, and attenuation in vivo. Two classes were found: interaction mutants and half-life mutants. The former suggest a key function for loop LIII of RNAIII as recognition loop in the primary steps of RNAII/RNAIII interaction.

Bacterial Proteins↗