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At least 631 records · Page 35Linked to original sources
PubMed1994

Plasmid pSC101 harbors a recombination site, psi, which is able to resolve plasmid multimers and to substitute for the analogous chromosomal Escherichia coli site dif.

Plasmid pSC101 harbors a 28-bp sequence which is homologous to dif, the target site of the XerC/XerD-dependent recombination system in Escherichia coli. Using a technique which allows very sensitive detection of plasmid loss, we show that recombination at this site, termed psi for pSC101 stabilized inheritance, causes a moderate increase in pSC101 stability. The role of the psi sequence in site-specific recombination has been explored in two other contexts. It was cloned in a derivative of plasmid p15A and inserted into the chromosome in place of dif. In the first situation, psi activity requires accessory sequences and results in multimer resolution; in the second situation, it suppresses the effects of the dif deletion and can promote intermolecular exchanges. Thus, psi is a site whose recombinational activity depends on the context, the first in the cer/dif family known to exhibit such flexibility.

Base Sequence↗
PubMed1996

The nucleotide sequence of a linear plasmid of Borrelia burgdorferi reveals similarities to those of circular plasmids of other prokaryotes.

A linear plasmid of Borrelia burgdorferi had 16,927 bp, a G+C content of 23.1%, a relative deficiency of CpG dinucleotides, and open reading frames A to O. The OrfC and OrfE proteins were similar to hypothetical proteins encoded by circular plasmids of B. burgdorferi. The OrfM and OrfN proteins were similar to replication proteins of circular plasmids of other bacteria.

Amino Acid Sequence↗
PubMed1997

Maintenance of broad-host-range incompatibility group P and group Q plasmids and transposition of Tn5 in Bartonella henselae following conjugal plasmid transfer from Escherichia coli.

The first demonstration of conjugal plasmid transfer from Escherichia coli to Bartonella henselae is reported. Transconjugants bearing plasmids of incompatibility groups P (IncP) and Q (IncQ), expressing various resistance markers, were generated. Tn5 transposons delivered on suicide plasmids by conjugation showed transpositional insertion into random chromosomal sites.

Bartonella henselae↗
PubMed1998

The Arcanobacterium (Actinomyces) pyogenes plasmid pAP1 is a member of the pIJ101/pJV1 family of rolling circle replication plasmids.

The 2.4-kb plasmid pAP1 from Arcanobacterium (Actinomyces) pyogenes had sequence similarity within the putative replication protein and double-stranded origin with the pIJ101/pJV1 family of plasmids. pJGS84, a derivative of pAP1 containing a kanamycin resistance gene, was able to replicate in Escherichia coli and Corynebacterium pseudotuberculosis, as well as in A. pyogenes. Detection of single-stranded DNA intermediates of pJGS84 replication suggested that this plasmid replicates by the rolling circle mechanism.

Actinomyces↗
PubMed2000

Minimal and contributing sequence determinants of the cis-acting locus of transfer (clt) of streptomycete plasmid pIJ101 occur within an intrinsically curved plasmid region.

Efficient interbacterial transfer of streptomycete plasmid pIJ101 requires the pIJ101 tra gene, as well as a cis-acting plasmid function known as clt. Here we show that the minimal pIJ101 clt locus consists of a sequence no greater than 54 bp in size that includes essential inverted-repeat and direct-repeat sequences and is located in close proximity to the 3' end of the korB regulatory gene. Evidence that sequences extending beyond the minimal locus and into the korB open reading frame influence clt transfer function and demonstration that clt-korB sequences are intrinsically curved raise the possibility that higher-order structuring of DNA and protein within this plasmid region may be an inherent feature of efficient pIJ101 transfer.

Bacterial Proteins↗
PubMed2001

Expression characteristics of the transfer-related kilB gene product of Streptomyces plasmid pIJ101: implications for the plasmid spread function.

Intermycelial transfer of Streptomyces plasmid pIJ101 occurs prior to cellular differentiation and is mediated by plasmid functions that are also required for production of zones of growth-inhibited recipient cells (i.e., pocks) that develop around individual donors during mating on agar medium. Several other pIJ101 functions, including that of the kilB gene, whose unregulated expression on pIJ101 is lethal, are required for normal pock size and so have been postulated to mediate intramycelial spread of the plasmid throughout recipient cells. Using antibodies raised against a KilB fusion protein expressed in Escherichia coli, native KilB protein was detected throughout development of pIJ101-containing Streptomyces lividans cells, with the concentration of KilB increasing dramatically and reaching a maximum during the final stages (i.e., sporulation and secondary metabolism) of cellular differentiation. Insertion of the kilB gene of pIJ101 into the S. lividans chromosome in cells lacking the pIJ101 KorB protein, which normally represses kilB gene transcription, resulted in elevated but still temporally increasing amounts of KilB. The increased expression or accumulation of the KilB spread protein throughout cellular differentiation of S. lividans, which leads to maximum KilB concentrations during developmental stages that occur far later than when intermycelial transfer of pIJ101 is mediated, supports the existence of a subsequent intramycelial component to the pIJ101 spread function. The results also suggest that intramycelial spread of pIJ101 molecules within the recipient extends beyond intercompartmental movements within the substrate mycelia and includes undetermined steps within the spore-yielding aerial hyphae as well.

Bacterial Proteins↗
PubMed2001

Genomic sequence and transcriptional analysis of a 23-kilobase mycobacterial linear plasmid: evidence for horizontal transfer and identification of plasmid maintenance systems.

Linear plasmids were unknown in mycobacteria until recently. Here, we report the complete nucleotide sequence of 23-kb linear plasmid pCLP from Mycobacterium celatum, an opportunistic pathogen. The sequence of pCLP revealed at least 19 putative open reading frames (ORFs). Expression of pCLP genes in exponential-phase cultures was determined by reverse transcriptase PCR (RT-PCR). Twelve ORFs were expressed, whereas no transcription of the 7 other ORFs of pCLP was detected. Five of the 12 transcribed ORFs detected by RT-PCR are of unknown function. Sequence analysis revealed similar loci in both M. celatum pCLP and the Mycobacterium tuberculosis chromosome, including transposase-related sequences. This result suggests horizontal transfer between these two organisms. pCLP also contains ORFs that are similar to genes of bacterial circular plasmids involved in partition (par operon) and postsegregational (pem operon) mechanisms. Functional analysis of these ORFs suggests that they probably carry out similar maintenance roles in pCLP.

Amino Acid Sequence↗
PubMed2002

Complete nucleotide sequence of plasmid Rts1: implications for evolution of large plasmid genomes.

Rts1, a large conjugative plasmid originally isolated from Proteus vulgaris, is a prototype for the IncT plasmids and exhibits pleiotropic thermosensitive phenotypes. Here we report the complete nucleotide sequence of Rts1. The genome is 217,182 bp in length and contains 300 potential open reading frames (ORFs). Among these, the products of 141 ORFs, including 9 previously identified genes, displayed significant sequence similarity to known proteins. The set of genes responsible for the conjugation function of Rts1 has been identified. A broad array of genes related to diverse processes of DNA metabolism were also identified. Of particular interest was the presence of tus-like genes that could be involved in replication termination. Inspection of the overall genome organization revealed that the Rts1 genome is composed of four large modules, providing an example of modular evolution of plasmid genomes.

Bacterial Proteins↗
PubMed1991

Interactions of plasmid-encoded replication initiation proteins with the origin of DNA replication in the broad host range plasmid RK2.

The TrfA proteins, encoded by the broad host range plasmid RK2, are required for replication of this plasmid in a variety of Gram-negative bacteria. Two TrfA proteins, 33 and 44 kDa in molecular mass (designated TrfA-33 and TrfA-44, respectively), are expressed from the trfA gene of RK2 through the use of two alternative in-frame start codons within the same open reading frame. The two proteins have been purified from Escherichia coli to near homogeneity as a mixture of wild-type TrfA-44/33, as TrfA-33 alone and as a functional variant form of TrfA-44, designated TrfA-44(98L), which contains a leucine in place of the TrfA-33 methionine start codon. Cross-linking experiments demonstrated that TrfA-33 can multimerize in solution. By using gel mobility shift and DNase I footprinting techniques the binding properties of TrfA-33, TrfA-44(98L), and TrfA-44/33 to the origin of replication of plasmid RK2 were analyzed. All three protein preparations were able to bind very specifically to the cluster of five direct repeats (iterons) contained in the minimal origin of replication. Each protein preparation produced a ladder of TrfA/minimal oriV complexes of decreasing electrophoretic mobility. The DNase I protection pattern on the five iterons was identical for all three protein preparations and extended from the beginning of the first iteron to 5 base pairs upstream of the fifth iteron. Studies on the affinity of the proteins for DNA fragments containing one, two, or all five iterons of the origin revealed a strong preference of TrfA protein for DNA containing at least two iterons. To study the stability of TrfA.DNA complexes, association and dissociation rates of TrfA-33 and DNA fragments with one, two, or five iterons were measured. This analysis showed that unlike complexes involving two or five iterons the TrfA/one iteron complexes were highly unstable, suggesting some form of cooperativity between proteins or iterons in the formation of stable complexes and/or the requirement of specific sequences bordering the iterons at the RK2 origin of replication for the stabilization of TrfA/DNA complexes.

Bacterial Proteins↗
PubMed1989

[The effect of thiocyanate on bacterial plasmids using the plasmid screening test].

A plasmid screening test (alkaline lysis and agarose gel electrophoresis) was used to assess the effect of thiocyanate on the plasmid replication on two bacterial strains with plasmids of different size, Klebsiella pneumoniae and Acinetobacter calcoaceticus. At concentrations physiologic for mammals (5-50 mg SCN-/l) no effect on the replication of extrachromosomal DNA was noted. This reaffirms the concept that a physiologic anion may be responsible for biological regulatory processes but will not affect the synthesis of extrachromosomal DNA when applied in vitro in physiologic concentrations.

Acinetobacter↗
PubMedDate not supplied

[Effect of a fragment of pBR322 plasmid in the region of tetracycline resistance gene on the stability of this plasmid].

A fragment destabilizing the pBR322 plasmid has been localized in the region of pBR322 tet gene promoter. On the basis of stability analysis of pBR322 derivatives comprising the modified region of tet gene, we deduced that it is the DNA sequence localized at the beginning of tet gene in the region of HindIII splitting site that ensures the plasmid destabilization, and not tet gene product or the active transcription of this region. The destabilizing effect of this fragment of the plasmid is manifested both in cis and in trans. Possible molecular mechanisms of the phenomenon are discussed.

DNA, Bacterial↗
PubMedDate not supplied

[Plasmid R1drd-19-mediated superoligomerization of the plasmid pACYC184in the recB mutant of Escherichia coli K12].

It was found that monomers of the pACYC184 plasmid undergo superoligomerization in a recB mutant of Escherichia coli K12 which is deficient in ATP-dependent RecBC nuclease and carries the drug resistance plasmid R1drd-19. The observed effect is specifically related to the ability of R1drd-19 to determine an ATP-dependent exonucleolytic activity which is functionally similar but not identical to the RecBC nuclease. The oligomerization of pACYC184 is accompanied by the formation of high-order circular structures, and this leads to elimination of the plasmid from cells growing under non-selective conditions.

Escherichia coli↗
PubMed1977

[Transgenosis with participation of plasmid RP1; indications of the presence of a "composit plasmid" in an interspecies hybrid of Escherichia coli].

One of the transconjugants (1-7) obtained by the authors earlier in the conjugation of Escherichia coli J-62 with Pseudomonas aeruginosa 1822, besides the plasmic RP1 has acquired the ability to grow without proline and tryptophan. The detailed analysis has shown that in the conjugation of the transconjugant 1-7 with different strains of E. coli the plasmic RP1 and chromosomal genes were transmitted together, but in transduction--by means of bacteriophage P1, independently of each other. The fertility was found only in the transductants carrying the plasmid RP1. This suggests that in the intergeneric conjugations the transmission of chromosomal genes may occur without any firm link with the plasmid (as in the case of "aggregated plasmids"). In E. coli cells these chromosomal fragments of Ps. aeruginosa apparently formed small nontransmissible replicons.

Chromosomes, Bacterial↗
PubMedDate not supplied

[Cloning of bacteriophage T5 DNA fragments in the plasmid pBR322. Analysis of recombinant plasmids by the method of bonding with RNA-polymerase from Escherichia coli on nitrocellulose filters].

DNA of bacteriophage T5 was hydrolyzed with restriction endonucleases HindIII and BamHI, and subjected to the combined hydrolysis with BamHI+EcoRI and BamHI+ +HindIII. Fragments obtained were cloned in the plasmid pBR322. About 17% of T5 genome were recovered in recombinant plasmids. Cloned fragments were localized on the physical map of the phage by restriction analysis and Southern hybridization. With the aim of direct cloning of T5 promoters, PstI/HindIII fragments were inserted into pBR322 followed by selection of recombinants on ApsTCr phenotype. Binding of BsuRI and AluI fragments of hybrid plasmids with E. coli RNA polymerase was studied by nitrocellulose filter assay. The fragments, which were capable to form heparin resistant complexes were identified.

Base Sequence↗
PubMed1984

[Mobilization for transfer of the nonconjugative plasmid pAP/57Hly by different conjugative plasmids].

The ability for mobilization of E. coli pAP57Hly nonconjugative plasmid which codes for beta-hemolysis production was investigated. It was shown that mobilization of pAP57Hly nonconjugative plasmid does not depend on the incompatibility groups, pili nature, host range of transmissible activity of conjugative plasmids. The data obtained exclude the mechanism of mobilization in which the cointegrative structures are formed.

Conjugation, Genetic↗
PubMed1982

[Integration of the genome of the Mu-like Pseudomonas aeruginosa bacteriophage D3112 into plasmid RP4 and its hybrid plasmid transfer into Pseudomonas putida and Escherichia coli C600 bacteria].

The genome of a Mu-like bacteriophage D3112 specific for Pseudomonas aeruginosa was integrated in vivo into the RP4 plasmid. The fact of integration has been proved by two experiments: 1. The loss of RP4 plasmid is accompanied by loss of D3112 prophage; 2. Transfer of the plasmid by conjugation from Pseudomonas aeruginosa into bacteria of other species - P. putida PgG1 or Escherichia coli C600 leads to the occurrence of clones of these species which liberate phage capable of growing on the lawn of P. aeruginosa bacteria. The integrated state of D3112 inserted into RP4 is stable in P. aeruginosa, E. coli, P. putida. The transfer frequency of RP4 with integrated D3112 prophage into different bacteria which do not contain homoimmune prophage is essentially lower than that of the RP4 having no D3112 prophage. Specific manifestation of D3112 genome activity in E. coli cells is the sensitivity of cell growth to lower temperature (30 degrees C) of incubation.

Bacteriophages↗
PubMed1983

[Comparative study of the plasmid DNA recipient capacity of Escherichia coli K-12 mutants for the main membrane proteins and of mutants with enhanced plasmid transformation efficiency].

The study of the plasmid transformation of E. coli K-12, carried out in mutants with the known damages in the main proteins of the outer membrane, made it possible to reveal the essential role of OmpA protein in this process. The damage of lipoprotein led to a considerable increase in the level of plasmid transformation. The mutants with the enhanced efficiency of plasmid transformation, obtained by the authors, were not connected with lesions in the main proteins of the outer membrane: OmpF, OmpC and OmpA.

Bacterial Outer Membrane Proteins↗