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At least 721 records · Page 40Linked to original sources
PubMed1991

Structural and functional comparison between the stability systems ParD of plasmid R1 and Ccd of plasmid F.

The stability determined by the systems ParD of plasmid R1 and Ccd of plasmid F is due to the concerted action of two proteins, a cytotoxin and an antagonist of this function. In this paper we report that CcdA and Kis proteins, the antagonists of the Ccd and ParD systems respectively, share significant sequence homologies at both ends. In Kis, these regions seem to correspond to two different domains. Despite the structural similarities, Kis and CcdA are not interchangeable. In addition we have shown that the cytotoxins of these systems, the Kid and CcdB proteins, do not share structural homologies. In contrast to CcdB, the Kid protein of the ParD system induces RecA-dependent cleavage of the cI repressor of bacteriophage lambda very inefficiently or not at all. The functional implications of these results are discussed.

Amino Acid Sequence↗
PubMed1978

Instability of plasmid DNA sequences: macro and micro evolution of the antibiotic resistance plasmid R6-5.

Detailed examination of the structure of cloned DNA fragments of the R6-5 antibiotic resistance plasmid has revealed a substantial degree of polynucleotide sequence heterogeneity and indicates that sequence rearrangements in plasmids and possible other replicons occur more frequently than has hitherto been appreciated. The sequences changes in cloned R6-5 fragments were shown in some instances to have occurred prior to cloning, i.e. existing in the original population of R6-5 molecules that was obtained from a single bacterial clone and by several different criteria judged to be homogeneous, and in others to have occurred either during the cloning procedure or during subsequent propagation of hybrid molecules. The molecular changes that are described involved insertion/deletion of the previously characterized IS2 insertion element, formation of a new inverted repeat structure probably by duplication of a preexisting R6-5 DNA sequence, sequence inversion, and loss and gain of restriction endonuclease cleavage sites.

Anti-Bacterial Agents↗
PubMed1988

Identification of psiB genes of plasmids F and R6-5. Molecular basis for psiB enhanced expression in plasmid R6-5.

PsiB protein of plasmid R6-5 inhibits the induction of the SOS pathway. The F sex factor also carries a psiB gene homologous to that of R6-5. Yet, it fails to inhibit SOS induction. In order to solve this difference, we characterized the psiB genes of R6-5 and F. We found that (i) the sequences of the two psiB genes share extensive homology the predicted amino acid sequences of the two proteins differing by 5 residues, (ii) the expression of R6-5 psiB is 4 times higher than F psiB gene, (iii) in plasmid R6-5, a Tn10 transposon upstream from the psiB gene enhances psiB expression. Hence, the F sex factor may be unable to prevent SOS induction for two non-exclusive reasons: (i) F PsiB protein, being slightly different from R6-5, may be less active, (ii) the level of synthesis of F PsiB protein may be insufficient to prevent SOS induction.

Amino Acid Sequence↗
PubMed1985

Molecular analysis of an antibiotic resistance plasmid, pAV5, and its derivative plasmids in Acinetobacter calcoaceticus.

The non-conjugative plasmid pAV5 specifies resistance to kanamycin/neomycin (KmR) and tetracycline (TcR). Physical evidence is presented to show that pAV5 gives rise to two plasmids, pAV51 (KmR) and pAV52 (TcR), which are formed by deletion of apparently non-overlapping segments of pAV5. Expression of TcR has been obtained in Escherichia coli and is associated with a 1.9 kb HindIII fragment found in pAV5 and in pAV52. Expression of KmR has been obtained in E. coli and is associated with a 1.3 kb PstI fragment found in pAV5 and pAV51. Evidence is presented that the KmR gene is flanked by inverted repeat sequences and is therefore tentatively identified as a transposon, designated Tn4411. The KmR gene specifies an aminoglycoside 3'-phosphotransferase-type I (APH(3')-I) enzyme.

Acinetobacter↗
PubMed1989

Nucleotide sequence of an OXA-2 beta-lactamase gene from the R-plasmid R1767 derived plasmid pBP11 and comparison to closely related resistance determinants found in R46 and Tn2603.

Plasmid pBP11 contains a sequence homologous to Tn21-like element Tn2410 encoding dihydropteroate synthetase and beta-lactamase OXA-2. The nucleotide sequence of a 1.5 kb segment of this region has been determined including the bla gene. It reveals strong sequence homology with the OXA-2 operon of plasmid R46. The implications of an additional 319 bp segment in pBP11 for the different evolution of R46/pKM101 and pBP11 are discussed.

Base Sequence↗
PubMed1979

Binding of ColE1-kan Plasmid DNA by Tobacco Protoplasts: Nonexpression of Plasmid Gene.

Protoplasts prepared from cultured tobacco cells were treated with ColE1-kan plasmid DNA, a hybrid of ColE1 and pSC105 plasmids bearing a gene for kanamycin resistance. The conditions employed permitted the uptake or irreversible binding of 2.9% of the added DNA in acid-insoluble form. Upon commencement of division, the treated cells were plated in agar medium containing kanamycin and differentiating hormones. Plantlets or shoots obtained as presumptive transformants were further tested on kanamycin medium by subculturing small leaf pieces. No evidence was obtained for expression of the kanamycin resistance gene of ColE1-kan in tobacco tissue.

Journal Article↗
PubMed1988

Conjugal transfer of group B streptococcal plasmids and comobilization of Escherichia coli-Streptococcus shuttle plasmids to Lactobacillus plantarum.

The antibiotic resistance group B streptococcal plasmids, pIP501 and pVA797, were conjugally transferred from Streptococcus faecalis to Lactobacillus plantarum. The Escherichia coli-Streptococcus shuttle plasmids, pVA838 and pSA3, were mobilized from S. sanguis to L. plantarum by pVA797 via cointegrate formation. pVA838 readily resolved from pVA797 and was present in L. plantarum as deletion derivatives. The pVA797::pSA3 cointegrate failed to resolve in L. plantarum.

Conjugation, Genetic↗
PubMed1973

Stimulation by cyclic adenosine monophosphate of plasmid deoxyribonucleic acid replication and catabolite repression of the plasmid deoxyribonucleic acid-protein relaxation complex.

Colicinogenic factors ColE1 and ColE2 are bacterial plasmids that exist in Escherichia coli as supercoiled deoxyribonucleic acid (DNA) and as strand-specific, relaxation complexes of supercoiled DNA and protein. Newly replicated ColE1 DNA becomes complexed with protein after the replication event. This association of DNA and protein can take place under conditions in which DNA or protein synthesis is arrested. The addition of cyclic adenosine monophosphate (c-AMP) to normal cells growing in glucose medium results in a six- to tenfold stimulation in the rate of synthesis of the protein component(s) of the complex and a three- to fivefold stimulation in the rate of ColE1 DNA replication. Employing mutants deficient in catabolite gene activator protein or adenylate cyclase, it was shown that synthesis of both the plasmid-determined protein colicin E1 and the protein component(s) of the ColE1 relaxation complex is mediated through the c-AMP-catabolite gene activator protein system. Addition of c-AMP to ColE2-containing cells results in the stimulation of synthesis of ColE2 DNA and relaxation protein(s) as well as in the production of a protein component of the ColE2 relaxation complex that renders it sensitive to induced relaxation by heat treatment. In the case of ColE2, synthesis of the relaxation protein(s) is not dependent upon catabolite gene activator protein.

Bacterial Proteins↗
PubMed1984

Enzymatic and nucleotide sequence studies of a kanamycin-inactivating enzyme encoded by a plasmid from thermophilic bacilli in comparison with that encoded by plasmid pUB110.

The product of a kanamycin resistance gene encoded by plasmid pTB913 isolated from a thermophilic bacillus was identified as a kanamycin nucleotidyltransferase which is similar to that encoded by plasmid pUB110 from a mesophile, Staphylococcus aureus. The enzyme encoded by pTB913 was more thermostable than that encoded by pUB110. In view of a close resemblance of restriction endonuclease cleavage maps around the BglII site in the structural genes of both enzymes, ca. 1,200 base pairs were sequenced, followed by amino-terminal amino acid sequencing of the enzyme. The two nucleotide sequences were found to be identical to each other except for only one base in the midst of the structural gene. Each structural gene, initiating from a GUG codon as methionine, was composed of 759 base pairs and 253 amino acid residues (molecular weight, ca. 29,000). The sole difference was transversion from a cytosine (pUB110) to an adenine (pTB913) at a position + 389, counting the first base of the initiation codon as + 1. That is, a threonine at position 130 for the pUB110-coded kanamycin nucleotidyltransferase was replaced by a lysine for the pTB913-coded enzyme. The difference in thermostability between the two enzymes caused by a single amino acid replacement is discussed in light of electrostatic effects.

Amino Acid Sequence↗
PubMed1987

Repressor gene finO in plasmids R100 and F: constitutive transfer of plasmid F is caused by insertion of IS3 into F finO.

Fertility factor F confers bacterial conjugation, a process which involves at least 20 tra genes. Resistance plasmids such as R100, R6-5, and R1 have homology with F in the tra region. Conjugal transfer of these plasmids is, however, repressed, while transfer of F is constitutive. Repression of R transfer is due to the existence of the two genes, called finO and finP; constitutive transfer of F is believed to be due to a lack of finO in F. In this paper, we report the identification and DNA sequence of the finO gene of R100, encoding a protein of 21,265 daltons. We show that F does actually encode finO, but the gene has been inactivated by insertion of IS3. Lederberg and Tatum (Nature [London] 158:558, 1946), who discovered sexuality in bacteria, may have had an Escherichia coli K-12 strain harboring such an finO F factor, which facilitated the generation of recombinant progeny useful for genetic analysis of bacteria and established the foundation for molecular genetics.

Amino Acid Sequence↗
PubMed1987

Influence of plasmids on bacterial susceptibility to the bactericidal activity of sera. II. Relation between transfer frequency of R plasmids and their protective activity to the lethal effect of normal rabbit serum.

The plasmid pAM-Ia separated from the aggregate R588 protected E. coli K12 cells from the bactericidal action of normal rabbit serum much stronger when carried alone than in the aggregate. When aggregated with R100.1, its protective effect was also weakened. These decreases in protective effect are correlated qualitatively with inhibition of conjugational fertility. On the other hand the plasmid aggregate causing increase in protective activity showed no influence on their fertility.

Animals↗
PubMed1977

Genetic properties of the Salmonella enteritidis R404 plasmid aggregate I. Conjugational separation of different derivative plasmid aggregates and their genetic properties.

Conjugational transfer of R404 factor, found in Salmonella enteritidis strain, was examined. Six derivative forms differing in resistance pattern were isolated. The manner of conjugational separation during transfer of R404 factor from E. coli to E. coli strain was the same as from the original strain of S. enteritidis to E. coli strain. During following conjugation, all isolated forms except one, could give forms differing in a resistance pattern from the parenteral ones. This one form, from which different conjugational forms could not be separated, was assumed to be a single plasmid and was designated pCK2. All other forms, including the original R404 factor were assumed to be plasmid aggregates.

Conjugation, Genetic↗
PubMed1996

The terminal protein of the linear DNA plasmid pGKL2 shares an N-terminal domain of the plasmid-encoded DNA polymerase.

The 36K protein attached at the 5' end of the linear DNA plasmid pGKL2 from the yeast Kluyveromyces lactis was first purified and characterized. The terminal protein was purified from cells (1 kg wet weight) by ammonium sulphate precipitation and two rounds of centrifugation to equilibrium in CsCl gradients. The pGKL2 was present only in the post-microsomal supernatant. Approximately 10 mg of the purified pGKL2 was recovered and digested with DNase I. The terminal protein (final ca. 0 center dot 8 mg) was homogeneous by electrophoresis and we determined the N-terminal amino acid sequence up to ten residues, showing that it existed in the cryptic N-terminal domain of pGKL2-ORF2 (DNA polymerase) sequence.

Amino Acid Sequence↗
PubMed1990

Electroporation and expression of plasmid pBR322 in Klebsiella aerogenes NCTC 418 and plasmid pRK2501 in Pseudomonas putida CYM 318.

Klebsiella aerogenes NCTC 418 and Pseudomonas putida CYM 318 were transformed via high-voltage electroporation with plasmids pBR322 and pRK2501, respectively. The number of transformants obtained was dependent on the applied voltage, capacitance, and cell recovery procedure. For example, 7.87 x 10(4) transformants/micrograms DNA were obtained at 2500 V, 25 muF when K. aerogenes cells were electroporated with pBR322 DNA. A lower voltage (1500) and capacitance (3 muF) yielded 2.4 x 10(3) transformants/micrograms DNA. P. putida CYM 318 required a 24 h outgrowth period to assist in the recovery of transformants containing pRK2501. Electroporation may be a useful protocol to transform bacterial strains that are not easily transformed by traditional methods.

Electricity↗
PubMed1996

Nucleotide sequence of plasmid p4028, a cryptic plasmid from Leuconostoc oenos.

The Leuconostoc oenos plasmid p4028 was cloned in pBlueScript (SK+), and its complete nucleotide sequence was determined. The analysis of the nucleotide sequence revealed five open reading frames, all of them located on the same strand and grouped in two clusters separated by a short noncoding stretch. A similarity search against the other sequences deposited in the EMBL and GenBank databases showed that p4028 has no significant similarity with any of the sequences checked. Nevertheless, a putative ATP-binding motif was found in ORF2. A more detailed analysis of this ORF suggests that it could encode for a DNA-dependent ATPase.

Amino Acid Sequence↗