Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| genome construction between bacterial species in vitro: replication and expression of staphylococcus plasmid genes in escherichia coli. | genes carried by ecori endonuclease-generated fragments of staphylococcus plasmid dna have been covalently joined to the e. coli antibiotic-resistance plasmid psc101, and the resulting hybrid molecules have been introduced into e. coli by transformation. the newly constructed plasmids replicate as biologically functional units in e. coli, and express genetic information carried by both of the parent dna molecules. in addition, electron microscope heteroduplex analysis of the recombinant plasmids ... | 1974 | 4598290 |
| replication and transcription of eukaryotic dna in escherichia coli. | fragments of amplified xenopus laevis dna, coding for 18s and 28s ribosomal rna and generated by ecori restriction endonuclease, have been linked in vitro to the bacterial plasmid psc101; and the recombinant molecular species have been introduced into e. coli by transformation. these recombinant plasmids, containing both eukaryotic and prokaryotic dna, replicate stably in e. coli. rna isolated from e. coli minicells harboring the plasmids hybridizes to amplified x. laevis rdna. | 1974 | 4600264 |
| the structures and fidelity of replication of mouse mitochondrial dna-psc 101 ecori recombinant plasmids grown in e. coli k12. | recombinant dnas containing the e. coli plasmid psc101 and mouse cell (la9) mitochondrial dna (mtdna) were formed in vitro via ligation of dna fragments from limit ecori endonuclease digests and were used to transform e. coli k12. four structurally different recombinant plasmid dnas from transformed clones were characterized. two of these were analyzed extensively and the mtdna portions compared with mtdna from la9 cells. no differences were detected in the physical or chemical properties examin ... | 1976 | 782720 |
| altered tetracycline resistance in psc101 recombinant plasmids. | investigation of tetracycline resistance genetically determined by the plasmid psc101 and several recombinants of psc101 containing ecori generated dna fragments inserted at the ecori site has revealed significant differences in the phenotypic expression of that resistance. the altered phenotypes of the recombinant plasmids may be the result of the location of the ecori site of psc101, which has been determined to be near the genetic elements involved with tetracycline resistance. | 1977 | 325378 |
| mutations of temperature sensitivity in r plasmid psc101. | temperature-sensitive (ts) mutant plasmids isolated from tetracycline resistance r plasmid psc101 were investigated for their segregation kinetics and deoxyribonucleic acid (dna) replication. the results fit well with the hypothesis that multiple copies of a plasmid are distributed to daughter cells in a random fashion and are thus diluted out when a new round of plasmid dna replication is blocked. when cells harboring type i mutant plasmids were grown at 43 degrees c in the absence of tetracycl ... | 1977 | 328479 |
| replication of plasmid psc101 in escherichia coli k12: requirement for dnaa function. | replication of psc101 was analyzed by using dna-dna hybridization and alkaline sucrose gradient centrifugation. mutants of the dnaa gene were tested for their capacity to replicate psc101 dna at a non-permissive temperature. only a small amount of radioactive precursor was incorporated into psc101 dna in dnaa mutants at 42 degrees c whereas active incorporation into plasmid dna took place in dnaa+ strain under the same conditions. the effect of the dnaa mutation was grater on plasmid dna synthes ... | 1977 | 337104 |
| sequence organization and expression of a yeast plasmid dna. | saccharomyces cerevisiae strain a364a d5 contains circular double-stranded dna molecules of 6230 +/- 30 base pairs (2mu dna) which are present in 68 copies per cell and make up 2.4% of the haploid genome. about 0.4% of non-poly a containing yeast rna hybridizes to the yeast dna circles. when denatured and then self-annealed, the dna molecules assume a characteristic "dumbbell" shape in the electron microscope indicating that each circle possesses a non-tandem inverted repeat sequence of 630 +/- ... | 1977 | 338416 |
| on the nature of tetracycline resistance controlled by the plasmid psc101. | in vitro enzymatic alteration of plasmid phenotype and in vitro construction of recombinant plasmids containing genetic information derived from the plasmid psc101 have been used to investigate the mechanism of function of tetracycline resistance determined by the plasmid psc101. the resistance has been shown to be inducible and involves the increased synthesis of membrane-associated polypeptides of 34,000, 26,000 and 14,000 daltons that are encoded for by the plasmid. the 34,000 dalton polypept ... | 1978 | 340050 |
| cloned dna fragment specifying major outer membrane protein a in escherichia coli k-12. | plasmid pmc44 is a recombinant plasmid that contains a 2-megadalton ecori fragment of escherichia coli k-12 dna joined to the cloning vehicle, psc101. the polypeptides specified by plasmid pmc44 were identified and compared with those specified by psc101 to determine those that are unique to pmc44. three polypeptides specified by plasmid pmc44 were localized in the cell envelope fraction of minicells: a sarkosyl-insoluble outer membrane polypeptide (designated m2), specified by the cloned 2-mega ... | 1978 | 361698 |
| the isolation and characterization of an in vivo recombinant between the filamentous bacteriophage f1 and the plasmid psc101. | 1978 | 362695 | |
| effect of dna mutations on the replication of plasmid psc101 in escherichia coli k-12. | escherichia coli strains with mutations in genes dnab, dnac, and dnag were tested for their capacity to replicate psc101 deoxyribonucleic acid (dna) at a nonpermissive temperature. only a small amount of radioactive thymine was incorporated into psc101 dna in the dna mutants at 42 degrees c, whereas active incorporation into plasmid dna took place in wild-type strains under the same conditions. the effects of the dnab and dnac mutations were greater on plasmid dna synthesis than on host chromoso ... | 1979 | 374337 |
| identification by deletion analysis of an inducible protein required for plasmid psc101-mediated tetracycline resistance. | 1979 | 384420 | |
| the effects of an escherichia coli dnaats mutation on the replication of the plasmids cole1 psc101, r100.1 and rtf-tc. | the rate of replication of the plasmids cole1, psc101, r100.1 and par132 (an rtf-tc derivative of the drug resistance factor r100.1) has been investigated directly by dna:dna hybridization. these rates have been compared, in a dnaats strain, to that of various markers of the host chromosome at permissive and non-permissive temperatures. chromosome initiation in the dnaats strain stops rapidly after a shift to the non-permissive temperature, but plasmids r100.1 and par132 do not seem to be affect ... | 1979 | 386040 |
| transposition of the escherichia coli insertion element gamma generates a five-base-pair repeat. | we have determined dna sequences surrounding the termini of the escherichia coli insertion element gamma delta, both at its normal locus on the f (fertility) factor and at three different sites of insertion into the plasmid pbr322. after transposition, a five-base-pair pbr322 sequence is duplicated and appears in direct orientation adjacent to each end of the element. no such duplication flanks the ends of gamma delta in f, and there is no apparent homology between the sequences surrounding gamm ... | 1979 | 388421 |
| plasmid psc101 replication in integratively suppressed cells requires dnaa function. | maintenance of plasmid pkc17, a derivative of plasmid psc101, in e. coli requires a functional dnaa gene product. this was demonstrated by segregation experiments using an e. coli dnaa46 mutant, at various temperatures. growth of this mutant at elevated temperature was allowed by the presence of a p2sig5 prophage. rpob mutations, which suppress the temperature sensitivity of a dnaa46 mutant permit efficient maintenance of plasmid pkc17 at temperatures up to 40 degrees, conditions which normally ... | 1979 | 390317 |
| cloning of the structural gene (ompa) for an integral outer membrane protein of escherichia coli k-12. | the gene (ompa) for the major outer membrane protein ii* from escherichia coli k-12 has been cloned on a 5-megadalton ecori fragment by using phage lambda as vector. the gene is expressed during the lytic cycle of the recombinant phage and the insoluble membrane-bound protein was detected in phage plaques with a simple radioimmunoassay. transfer of the ecori fragment into plasmid psc101 and expression in a host lacking protein ii* led to overproduction of protein ii* and decreased production of ... | 1979 | 159455 |
| organization of a hybrid between phage f1 and plasmid psc101. | we have characterized the 200-nucleotide-long insertion found in f1 after segregation of a chimeric phage containing the genomes of f1 and psc101 [ohsumi, m., vovis, g.f. & zinder, n.d. (1978) virology 89, 438--449]. the insertion in this novel f1 species, called f1', is derived from psc101 and has the potential to form an extended base-paired secondary structure, as determined by nucleotide sequence analysis. a five-nucleotide direct repeat, derived from f1 sequences, is present in f1'. the 200 ... | 1979 | 287058 |
| organization of chimeras between filamentous bacteriophage f1 and plasmid psc101. | 1980 | 6265643 | |
| insertion element is102 resides in plasmid psc101. | in vivo recombination was found to occur between plasmid phs1, a temperature-sensitive replication mutant of psc101 carrying tetracycline resistance, and plasmid cole1 after selection for tetracycline resistance at the restrictive temperature, 42 degrees c. extensive analysis of the physical structures of three of these recombinant plasmids, using restriction endonucleases and the electron microscope heteroduplex method, revealed that the plasmid phs1 was integrated into different sites on cole1 ... | 1980 | 6252187 |
| structure of a promotor on plasmid pmb9 derived from plasmid psc101. | the dna sequence of a 354 basepair ecori-hindiii fragment of plasmid pmb9 which has originally been derived from plasmid psc101 has been resolved. this fragment contains a promoter for transcription directed towards the ecori site. escherichia coli rna polymerase binds to a region within the ecori-hindiii fragment which contains the heptamer 5' tatggtg (132-126) and the duodecamer 5' tgatgaacatca (158-147). based on commonalities with other promotors these dna sequences probably function as, res ... | 1980 | 6253940 |
| cloning of an ecori-generated fragment of the leucine operon of salmonella typhimurium. | recombinant plasmids carrying part of the leucine operon of salmonella typhimurium were isolated following transformation of an escherichia coli leucine auxotroph to prototrophy with a ligated mixture of ecori-treated salmonella dna and plasmid psc101 dna. plasmids pcv11 and pcv13, containing a 3.4-10(6) dalton dna fragment ligated to the vector, had the leu operon oriented in opposite directions. the orientation of the leu operon relative to plasmid genes was determined. the 3.4-10(6) dalton fr ... | 1980 | 6987127 |
| phenotypic stability of trp operon recombinant plasmids in escherichia coli. | the recombinant plasmids rsf2124-trp and psc101-trp were examined for their phenotypic stability in escherichia coli w3110 and its derivatives under various culture conditions. rsf2124-trp and psc101-trp were stable in a trpae1 strain. in an amber mutant of the tryptophan repressor gene, rsf2124-trp was fairly stable, whereas psc101-trp was unstable. all trp- segregants from the psc101-trp carrier had lost the entire plasmid. in a mutant carrying the tnaa mutation, rsf2124-trp was unstable in ri ... | 1980 | 6999123 |
| effect of nalidixic acid and novobiocin on pbr322 genetic expression in escherichia coli minicells. | the effects of two deoxyribonucleic acid (dna) gyrase inhibitors, nalidixic acid and novobiocin, on the gene expression of plasmid pbr322 in escherichia coli minicells were studied. quantitative estimates of the synthesis of pbr322-coded polypeptides in novobiocin-treated minicells showed that the synthesis of a polypeptide of molecular weight of 34,000 (the tetracycline resistance protein) was reduced to 11 to 20% of control levels, whereas the amount of a polypeptide of 30,500 (the beta-lactam ... | 1981 | 7031033 |
| site-specific deletions in the recombinant plasmid psc101 containing the redb-ori region of phage lambda. | large deletions occur in the hybrid plasmid formed by psc101 and the ecori fragment f2 of phage lambda (redb-ori region) under well defined growth conditions (bernardi and bernardi, 1980). we have sequenced the novel joints of the four deletions so obtained and shown that they have one endpoint in psc101, identical in all four cases, the other endpoint being located in four different lambda sequences. furthermore, the nucleotide sequences of the novel joints show homologies between the conserved ... | 1981 | 6263749 |
| complete sequence of an is element present in psc101. | recently a new insertion element (is102)b ha been described in plasmid psc101. we have determined its complete sequence: it consists of 1057 bp; 338 bp at one end are identical to those already determined for the kanamycin resistance transposon tn903. it is not flanked by any direct repeat. its coding capabilities are discussed, and compared to those of is903. | 1981 | 6269064 |
| specific-purpose plasmid cloning vectors. i. low copy number, temperature-sensitive, mobilization-defective psc101-derived containment vectors. | two cloning vector plasmids, phsg415 (7100 bp) and a lambda phage cos site-containing derivative (cosmid) thereof, phsg422 (8760 bp), were constructed from a low copy number plasmid (psc101) replicon to permit the propagation of cloned dna segments at low gene dosage levels. two features of the vectors, namely temperature sensitivity of replication and inability to be mobilized by conjugative plasmids, cause them to exhibit a high level of "biological containment". the essential characteristics ... | 1981 | 6282694 |
| new approach to tryptophan production by escherichia coli: genetic manipulation of composite plasmids in vitro. | for the purpose of studying the production of l-tryptophan by escherichia coli, the deletion mutants of the trp operon (trpae1) were transformed with mutant plasmids carrying the trp operon whose anthranilate synthase and phosphoribosyl anthranilate transferase (anthranilate aggregate), respectively, had been desensitized to tryptophan inhibition. in addition to release of the anthranilate aggregate from the feedback inhibition required for plasmids such as psc101 trp.i15, the properties of trp ... | 1982 | 7036897 |
| temperature sensitive replication plasmids are passively distributed during cell division at non-permissive temperature: a new model for replicon duplication and partitioning. | to see whether plasmid molecules in bacteria are equally partitioned or randomly distributed at cell division, the segregation properties of temperature sensitive replication mutants of the e. coli plasmid psc101 were tested at non-permissive temperature. the results support the idea that at least unreplicated molecules are passively distributed and thus the equipartition model is unlikely even under physiological conditions if plasmids replicate randomly. therefore, we developed a new model whi ... | 1982 | 6757666 |
| primary structure of the essential replicon of the plasmid psc101. | the replicon of the low copy number plasmid psc101 has an obligatory requirement for the dnaa initiator protein of escherichia coli as well as a plasmid-encoded initiator protein. we have identified the cistron of the plasmid-encoded initiator by dna sequence analysis. fusion of the initiator cistron with the lacz gene of e. coli yielded a fusion protein of approximately equal to 150 kilodaltons, thus confirming that the open reading frame detected by dna sequence analysis actually encoded a 37. ... | 1983 | 6579542 |
| the use of a partition locus to increase stability of tryptophan-operon-bearing plasmids in escherichia coli. | the stability of different derivatives of plasmid vectors pbr322 and pacyc184 carrying the tryptophan operon of escherichia coli was monitored in various media. it was found that in the absence of any special selective pressure, all plasmids were lost from the culture. the stability varied depending both on the orientation of the inserted tryptophan fragment and the growth media used. the pbr322::trp+ plasmids were lost at an average frequency of 0.3 to 0.8% per cell generation, while the pacyc1 ... | 1983 | 6352412 |
| nucleotide sequence of the partition locus of escherichia coli plasmid psc101. | we report here the sequence of a 375-bp ecori-avai dna fragment that previously has been shown to contain a locus (termed partition or par) responsible for stable maintenance of the psc101 plasmid in growing cell populations. the dna sequence of the par region encodes no obvious proteins and contains no segments having the structural characteristics of transcriptional or translational start signals. however, segments of the par locus appear capable of forming regions of intra-strand secondary st ... | 1983 | 6357952 |
| the nucleotide sequence of replication and maintenance functions encoded by plasmid psc101. | the nucleotide sequence of 1100bp around the origin of replication of the psc101 plasmid has been determined. this segment of dna is capable of replication in the presence of a helper plasmid. the sequence data reveal similarities between psc101 and several other replicons. the origin of replication contains three direct repeats of an 18bp sequence associated with a segment exceptionally rich in a-t base pairs. a promotor that probably directs transcription of a gene encoding an essential plasmi ... | 1983 | 6310509 |
| plasmid psc101 replication mutants generated by insertion of the transposon tn1000. | a derivative of psc101, plc709, was constructed by ligation of the hincii-a fragment of psc101 to the mini-colei plasmid pvh51 and to a dna fragment encoding resistance to the antibiotics streptomycin and spectinomycin. insertions of the transposon tn1000 (gamma-delta) into the psc101 replication region of plc709 were isolated following cotransfer of the plasmid with the sex factor f. the sites of insertion of the transposon were determined by restriction enzyme analysis and the replication and ... | 1983 | 6313942 |
| dna-protein interaction at the origin of dna replication of the plasmid psc101. | the initiation of dna replication of the low copy number plasmid psc101 is dependent on the dnaa initiator protein encoded by escherichia coli. we have previously reported that the minimum essential replicon of the plasmid encodes a approximately 37.5 kd protein and that the protein is necessary along with host-encoded proteins for the replication of the plasmid chromosome. in this communication we show that the plasmid-encoded protein has sequence-specific dna-binding activity. the protein bind ... | 1983 | 6317193 |
| a 37 x 10(3) molecular weight plasmid-encoded protein is required for replication and copy number control in the plasmid psc101 and its temperature-sensitive derivative phs1. | nucleotide sequences were determined for a region essential for autonomous replication and partitioning of psc101, a plasmid whose replication is dependent on the escherichia coli dnaa gene product. the essential replication region contains one long coding sequence, rep101 , for a protein composed of 316 amino acids, and a polypeptide approximately 37 x 10(3) mr in size was identified as the rep101 gene product. rep101 is preceded by two inverted repeat sequences, three directly repeated sequenc ... | 1984 | 6327996 |
| construction and characterization of new cloning vehicles. vii. construction of plasmid pbr327par, a completely sequenced, stable derivative of pbr327 containing the par locus of psc101. | in vitro recombinant dna experiments, using plasmid pbr327 and a dna fragment derived from plasmid psc101 containing the par region, resulted in the construction of plasmid pbr327par. this new cloning vehicle has all the cloning properties of the parental plasmid, and is more stable than pbr327. since the nucleotide sequence of the par region has been determined, this new vector is completely characterized. some features of the sequence with possible functional significance are discussed. | 1984 | 6329912 |
| in vitro deletions in the partition locus of plasmid psc101. | deletion mutants in the 375-base-pair ecori-avai fragment carrying the partition locus of plasmid psc101 were formed by the combined action of exonuclease iii and nuclease s1. six deletion mutants were isolated, and the endpoints of the deletions were sequenced. one of the deletions extended 69 base pairs from the ecori site without impairing plasmid stability. the other five deletions caused the plasmid to be unstable and extended 199 to 251 base pairs from the ecori site. | 1984 | 6090432 |
| the replication origin of psc101: the nucleotide sequence and replication functions of the ori region. | the nucleotide sequence of a 770-bp ori region of plasmid psc101 is presented. the sequence shows homologies to some parts of escherichia coli oric and phage g4 ori. several other features are an 80-bp a + t-rich region overlapping a part of the region homologous to oric, three direct repeats of an 18-bp sequence adjacent to the a + t-rich region, a typical promoter sequence just upstream of the longest open reading frame (orf) and a long inverted repeat sequence overlapping the putative promote ... | 1984 | 6092223 |
| staphylococcal plasmid cointegrates are formed by host- and phage-mediated general rec systems that act on short regions of homology. | cointegrates involving pairs of compatible staphylococcal plasmids can be isolated either by co-selection during transduction (novick et al. 1981) or by selection for survival at the restrictive temperature of a thermosensitive, replication defective plasmid in the presence of a stable one. cointegrates are formed by recombination at two specific sites, rsa and rsb. rsb is present on each of six plasmids analyzed, namely pt181, pe194, pc194, ps194, pub110, and psn2, and rsa is present on two of ... | 1984 | 6092862 |
| replication functions encoded by the plasmid psc101. | we describe the mapping of several genetic loci involved in the replication of the psc101 plasmid. these include the origin of replication and a short segment of dna that encodes a psc101 incompatibility function. this short segment lies within the origin region. flanking the incompatibility segment are two loci, repa and repb, which are required for replication. the product of the repa locus is shown to be trans-acting. | 1984 | 6098153 |
| a psc101-derived plasmid which shows no sequence homology to other commonly used cloning vectors. | we have constructed a plasmid cloning vector, pgb2, which is derived from the escherichia coli plasmid psc101. the plasmid, which specifies resistance to spectinomycin and streptomycin, contains unique restriction sites for the enzymes hindiii, psti, sali, bamhi, smai and ecori. pgb2 shows no sequence homology, as detected by dna-dna hybridization, to several widely used vectors such as pbr322, puc8 and phage lambda l47.1. amongst other applications, dna fragments can be cloned into the plasmid ... | 1984 | 6098521 |
| characterization of the escherichia coli ssb-113 mutant single-stranded dna-binding protein. cloning of the gene, dna and protein sequence analysis, high pressure liquid chromatography peptide mapping, and dna-binding studies. | the ssb-113 (formerly lexc113) gene encoding a mutant single-stranded dna binding protein (ssb) has been cloned into plasmid psc101 resulting in 5- to 10-fold more mutant protein than strains carrying only one (chromosomal) copy of the gene. analysis of tryptic and chymotryptic peptides of the mutant protein by high pressure liquid chromatography and solid phase protein sequencing has shown that the ssb-113 mutation results in the substitution of serine for proline at residue 176 of ssb. this ch ... | 1984 | 6363409 |
| overinitiation of chromosome and plasmid replication in a dna acos mutant of escherichia coli k12. evidence for dnaa-dnab interactions. | the dnaacos mutations are phenotypic suppressors of dnaats46 that are co-transduced with dnaa, render the cell cold sensitive, and cause an excess of chromosome replication relative to cell mass when the cells are shifted from 42 degrees c to 32 degrees c. we have used pulse labelling and dna-dna hybridization to follow the effect of a temperature shift on the replication of the chromosome and of the plasmids psc101, rtf-tc, and lambda dv in such strains. after a shift of a dnaacos strain from 4 ... | 1984 | 6389885 |
| maintenance of plasmid psc101 in escherichia coli requires the host primase. | the abilities of three escherichia coli strains with thermosensitive dnag alleles to maintain plasmids psc101 or pbr322 or an rp4 derivative were studied at elevated growth temperatures. under these conditions, psc101 segregated from cells to a greater extent than did pbr322. no segregation of the primase-encoding rp4 derivative was observed. | 1985 | 3900047 |
| an essential replication gene, repa, of plasmid psc101 is autoregulated. | measurements of the rate of replication of a mutant psc101 plasmid, cloned into a cole1 vector, showed that insertions of the transposon tn1000 into the repa gene of psc101 abolished replication activity, but could be complemented in trans, albeit at a low level. the promoter of the repa gene was mapped by the construction of repa-lacz gene fusions, and one of the fusions was used to demonstrate that repa protein, provided in trans, could repress expression of beta-galactosidase activity. this r ... | 1985 | 2984435 |
| the replication initiator protein of plasmid psc101 is a transcriptional repressor of its own cistron. | the plasmid-encoded replication initiator protein of psc101 specifically repressed initiation of transcription of its own cistron from its natural promoter. addition of the purified initiator had little or no visible effect on transcription initiated from a heterologous promoter. dnase protection experiments revealed that the rna polymerase recognition sequence was overlapped by the initiator protein recognition sequences, which are vicinal to the replication origin. using the labeled promoter s ... | 1985 | 2986108 |
| cointegration and resolution mediated by is101 present in plasmid psc101. | a certain class of cointegrate plasmids was found to occur between a psc101 derivative and a second plasmid pbv320 in e. coli f- cells. cleavage analysis and dna sequencing showed that the cointegrate plasmid contained direct repeats of an insertion sequence is101 at the recombination junctions, indicating that formation of cointegrates was mediated by is101, which is a natural constituent of psc101. these cointegrates were formed only in cells which contained the transposon gamma-delta, suggest ... | 1985 | 2993789 |
| autogenous regulation of synthesis of the replication protein in plasmid psc101. | a 1.3-kb segment of plasmid psc101 includes the replication origin (ori) and the gene (rep) encoding the 37 kilodalton (k) protein required for autonomous replication of the plasmid. the present work describes the regulation of the rep gene expression. the gamma promoters pr and pl fail to promote rep gene expression when located upstream of a sequence with dyad symmetry overlapping the rep promoter, whereas elimination of this sequence allows expression and results in over-production of the rep ... | 1985 | 2995761 |
| orientation and sequence analysis of right ends and target sites of bacteriophage mu and d108 insertions in the plasmid psc101. | we have isolated four independent insertions of the entire 37-kb d108cts 10 genome in the low-copy-number plasmid psc101 in vivo. they were all formed by replicative transposition during the d108 lytic cycle. the orientation of these four insertions was found to be the same, with the left ends facing towards psc101 replication, and the right end facing in the direction of all psc101 transcription, as was previously found for a mucts62 insertion in psc101, pmc321. the exact sites of insertion of ... | 1986 | 3011604 |
| regions associated with the stable maintenance of plasmid psc101 and its tetracycline resistance. | two regions tentatively called unsa and unsr were identified on psc101. one, unsa, corresponds to less than 650 bp of the n-terminal in the tetracycline resistance structural gene and seems to inhibit stable maintenance of psc101. the other, unsr, is defined within the 1 kb xhoi-ecori region located upstream of the tetracycline resistance structural gene and is a regulatory gene clearly distinct from tetr (unger et al. 1984); it serves as a suppressor of the unsa function. | 1986 | 3018437 |
| selection of lambda spi- transducing phages using the p2 old gene cloned onto a plasmid. | the old gene product of the p2 prophage interferes with plaque formation by lambda wild type phage but allows lambda phages whose red and gam genes have been deleted to form small, visible plaques (the lambda spi- phenotype). the old gene product also kills escherichia coli recb or recc mutants. we have cloned the old gene into the high-copy-number plasmid pbr322, where it prevents plaque formation by both lambda spi+ and lambda spi- phages. we transferred a dna fragment that carries the old gen ... | 1986 | 3026928 |
| host participation in plasmid maintenance: dependence upon dnaa of replicons derived from p1 and f. | nonparticipation of the bacterial dnaa gene in plasmid replication has been assumed to be the general rule. in conditional dnaa mutants of escherichia coli, only plasmid psc101 has been shown to have a dnaa requirement. experiments with dnaa null mutants of e. coli, presented here, show that dnaa plays a critical and direct role in the replication of miniplasmids derived from p1 and f as it does in the initiation of bacterial replication. evidence is also presented for the existence of a dnaa-in ... | 1986 | 3520571 |
| replication of psc101: effects of mutations in the e. coli dna binding protein ihf. | we have shown that the plasmid psc101 is unable to be maintained in strains of e. coli carrying deletions in the genes hima and hip which specify the pleitropic heterodimeric dna binding protein, ihf. we show that this effect is not due to a modulation of the expression of the psc101 repa protein, required for replication of the plasmid. inspection of the dna sequence of the essential replication region of psc101 reveals the presence of a site, located between the dnaa binding-site and that of r ... | 1986 | 3528758 |
| the integration host factor of escherichia coli binds to bent dna at the origin of replication of the plasmid psc101. | the integration host factor (ihf) of escherichia coli is necessary for maintenance of psc101. the protein binds specifically to the replication origin of the plasmid, in the at-rich region located immediately adjacent to the left, weak binding site for the plasmid-encoded initiator protein. dnaase i and oh- radical footprinting experiments showed that ihf protects 49 bp of the dna at the origin region. methylation protection analyses revealed that ihf contacts purine residues in both the major a ... | 1987 | 3555843 |
| fate of the dna in plasmid-containing escherichia coli minicells ingested by human neutrophils. | escherichia coli minicells containing the plasmid psc101 (approximately 10 kb) or pbr322 (approximately 4 kb) were opsonized and incubated with human neutrophils. the neutrophils responded to the minicells as they would to native e coli: they ingested the minicells, discharged their granule contents into the minicell-containing phagosomes, and expressed a respiratory burst. after one hour of incubation, the fate of the ingested plasmid dna was examined. no dna degradation was detected by trichlo ... | 1987 | 3032306 |
| the partition locus of plasmid psc101 is a specific binding site for dna gyrase. | a protein in extracts of escherichia coli that specifically binds the stabilizing par sequence of psc101 was identified as dna gyrase. the purified enzyme protects par against digestion by dnase i and exonuclease iii. competition assays demonstrate that gyrase has a 40-fold higher affinity for the 100-bp par sequence than for nonspecific dna and that par is the major gyrase-binding site in psc101 derivatives used in this and other studies. within par, at-rich sequences occur with a pronounced 10 ... | 1988 | 2844527 |
| involvement of integration host factor (ihf) in maintenance of plasmid psc101 in escherichia coli: characterization of psc101 mutants that replicate in the absence of ihf. | escherichia coli mutants defective in the stable maintenance of plasmid psc101 have been isolated following tn10 insertion mutagenesis. one class of mutations affecting psc101 replication was located in the genes hima and himd (hip), which encode the two subunits of integration host factor (ihf), a small histonelike dna-binding protein that has multiple cellular functions. mutants of psc101 that could replicate in the absence of ihf were isolated and characterized; four independent mutational al ... | 1989 | 2539358 |
| involvement of integration host factor (ihf) in maintenance of plasmid psc101 in escherichia coli: mutations in the topa gene allow psc101 replication in the absence of ihf. | integration host factor (ihf), encoded by the hima and himd genes, is a histonelike dna-binding protein that participates in many cellular functions in escherichia coli, including the maintenance of plasmid psc101. we have isolated and characterized a chromosomal mutation that compensates for the absence of ihf and allows the maintenance of wild-type psc101 in him mutants, but does not restore ihf production. the mutation is recessive and was found to affect the gene topa, which encodes topoisom ... | 1989 | 2539359 |
| nucleotide sequences from the colicin e5, e6 and e9 operons: presence of a degenerate transposon-like structure in the cole9-j plasmid. | the nucleotide sequences of 1288 bp of plasmid cole5-099, 1609 bp of cole6-ct14 and 2099 bp of cole9-j were determined. these sequences encompass the structural genes for the c-terminal receptor-binding and nuclease domains of colicins e5, e6 and e9, their cis- or trans-acting immunity proteins and four lysis proteins including an atypical one of non-lipoprotein nature (lys) present in the cole9-j plasmid. the cole6 gene organisation, in the order col-imm-e8imm-lys, is identical to that found in ... | 1989 | 2549375 |
| transcription events in the origin of replication of plasmid psc101. | insertion mutations were isolated in the origin fragment of the plasmid psc101 after random cleavage with dnase i. the replication properties of the resulting plasmids confirmed previous findings and extended the characterization of the essential regions. using these plasmids, we analyzed by various methods the transcription events in the psc101 origin. in addition to the mrna of repa, a gene coding for the self-regulated repa protein which is essential for replication of the plasmid, we charact ... | 1989 | 2556365 |
| effect of the pem system on stable maintenance of plasmid r100 in various escherichia coli hosts. | we cloned the pem segment of plasmid r100 containing the two genes pemi and pemk, which are responsible for stable maintenance of r100 in dividing cells, into phs1, a temperature-sensitive replication mutant of plasmid psc101. we then examined the effect of the pem system on the maintenance of the resultant pem+ plasmid pdom17 in various escherichia coli host strains upon inhibition of replication of the plasmid at a high temperature. we show that the pem+ plasmid was maintained stably in the ce ... | 1989 | 2651892 |
| [transposition of the composite synthetic transposon tnv (tn5-rep(psc101)) is accompanied by the formation of the mini-plasmid ptnv, containing defective is50-elements]. | using thermoelimination (at 42 degrees c) of the thermoinducible coliphage p1tscmr omega::tnv (tnv is a tn5 derivative which contains the replication origin (rep) of plasmid psc101), more than 110 kmrcms escherichia coli k12 clones were selected. it was supposed that the kmrcms phenotype could result only from insertion of tnv (kmr) into e. coli chromosome and the loss of phage (cms). it was found that the majority of kmrcms clones (35-90%) contained miniplasmids. their molecular sizes did not e ... | 1990 | 1963206 |
| dna binding properties of purified replication initiator protein (rep) encoded by plasmid psc101. | we have purified the replication initiator protein (rep) coded by plasmid psc101. the purified protein was confirmed to be rep by its amino-terminal sequence. rep exists as a dimer and has a sequence-specific dna-binding property. protection experiments with dna against cleavage by dnase i or exonuclease iii showed that rep bound preferentially to two nearly dyad-symmetric sequences overlapping the promoter of the rep gene, a structure gene of rep. transcripts in vitro from the rep promoter were ... | 1990 | 2187857 |
| the mobilization and origin of transfer regions of a thiobacillus ferrooxidans plasmid: relatedness to plasmids rsf1010 and psc101. | the components for the mobilization function of a plasmid dna during conjugation include a cis-acting sequence (the origin of transfer, orit) and a transacting sequence coding for mobilization (mob) proteins. by genetic and deletion analysis, we have located the mobilization region of ptf1, a cryptic plasmid previously isolated from a thiobacillus ferrooxidans strain. within a 2797 bse-pair sequenced region, several open reading frames (orfs) were predicted; two of the orfs are divergently trans ... | 1990 | 2280689 |
| use of a dual-origin temperature-controlled amplifiable replicon for optimization of human interleukin-1 beta synthesis in escherichia coli. | a new dual-replicon recombinant plasmid, ppr53-tsr, has been constructed; it is a derivative of the expression vector ppr-tgatg-1 [mashko et al., gene 88 (1990) 121-126]. in contrast to its progenitor, ppr53-tsr is a low-copy-number (low-cop) plasmid amplifiable in temperature-dependent fashion. in addition to both the replicon and the par locus from plasmid psc101, providing segregational stability and a low cop at 28 degrees c, the new plasmid contains a mutant cole1 replicon whose rnaii is sy ... | 1991 | 1999290 |
| the replication of plasmid psc101. | the origin of replication of plasmid psc101 presents features reminiscent of those found in a number of plasmids. as for those plasmids, many details about the way it initiates its replication are beginning to be known, but the regulation of this process will not be easily understood. | 1991 | 2041467 |
| a copy-number mutant of plasmid psc101. | copy-number mutants of plasmid psc101 were isolated by u.v. mutagenesis and selection for elevated expression of ampicillin resistance. three independent mutations were identical and mapped in codon 93 of the initiation protein repa. the mutated plasmids were maintained at a level four to five times higher than that of the wild type. for one of them, it was determined that: (i) the mrna of the autoregulated repa gene, cloned onto a puc19 plasmid under the control of its own promoter, was express ... | 1991 | 1710758 |
| a single-stranded region located downstream of the repeated sequence in the ori region of psc101 is required for binding of the rep protein in vitro. | purified replication initiator protein (rep) of plasmid psc101 binds preferentially to two inverted repeats (ir) overlapping the promoter of its own structure gene, rep. however, the protein has much lower binding affinity for directly repeated (dr) sequences in the replication origin (ori) that are similar to the symmetric sequences. exonuclease iii (exo iii) promotes in vitro binding of rep to the origin repeats. in the present studies, dna containing the dr sequences was degraded unidirection ... | 1991 | 1838376 |
| exonuclease iii promotes in vitro binding of the replication initiator protein of plasmid psc101 to the repeated sequences in the ori region. | purified rep protein, a replication initiator protein of plasmid psc101, has less binding affinity for the direct repeats (dr) in the replication origin region (ori) than that for the inverted repeats (ir) in the promoter region of the structure gene of rep (rep) (sugiura, s. et al. (1990) j. biochem. 107, 369-376). we found a protein factor that promotes binding of purified rep to the dr sequence in the cell extract of escherichia coli. in the presence of the factor, dna fragments containing th ... | 1991 | 1859836 |
| analysis of a copy number mutant of plasmid psc101: co-maintenance of wild type and mutant plasmids. | we have isolated a high copy number mutant of plasmid psc101 which is maintained at a level 4 times higher than that of the wild type. the mutation is a single base change that maps in codon 93 of the initiation protein repa. we find that the mutation relaxes the autoregulation of the protein but increases its affinity for the repeated sequences in the origin. the wild type and the mutant repa genes are co-dominant and the mutated protein acts in trans even in the presence of the wild type prote ... | 1991 | 1925012 |
| propagation of psc101 plasmids defective in binding of integration host factor. | integration host factor (ihf), a multifunctional protein of e. coli, normally is required for the replication of plasmid psc101. t. t. stenzel, p. patel, and d. bastia (cell 49:709-717, 1987) have reported that ihf binds to a dna locus near the psc101 replication origin and enhances a static bend present in this region; mutation of the ihf binding site affects the plasmid's ability to replicate. we report here studies indicating that the requirement for ihf binding near the psc101 replication or ... | 1992 | 1310092 |
| a psc101-par sequence-mediated study on the intracellular state of supercoiling of the pbr322 genome in escherichia coli dna topoisomerase i deletion mutant. | in escherichia coli dna topoisomerase i deletion mutant dm800, transcription of the tetracycline-resistance gene (tet) in the pbr322 genome is thought to create and maintain two domains of positive supercoils ahead, and negative supercoils behind, the transcription complex. to assess the actual intracellular state of twin-supercoiled domains, par sequence (365 bp) of plasmid psc101, which shows a high affinity for dna gyrase, was inserted into the ecori site upstream, or the avai site downstream ... | 1992 | 1324199 |
| monomers and dimers of the repa protein in plasmid psc101 replication: domains in repa. | the replication of plasmid psc101 requires the plasmid-encoded protein repa. this protein has a double role: it binds to three directly repeated sequences in the psc101 origin and promotes replication of the plasmid; it binds to two inversely repeated sequences in its promoter region and regulates its own transcription. a series of repa protein derivatives carrying deletions of the c-terminal region were assayed for specific binding. we found that the last third of the protein is not needed for ... | 1992 | 1409587 |
| replication of the promiscuous plasmid pls1: a region encompassing the minus origin of replication is associated with stable plasmid inheritance. | deletion of a region of the promiscuous plasmid pls1 encompassing the initiation signals for the synthesis of the plasmid lagging strand led to plasmid instability in streptococcus pneumoniae and bacillus subtilis. this defect could not be alleviated by increasing the number of copies (measured as double-stranded plasmid dna) to levels similar to those of the wild-type plasmid pls1. our results indicate that in the vicinity of, or associated with the single-stranded origin region of pls1 there i ... | 1993 | 8232217 |
| a pseudo-symmetric dna binding motif of purified rep dimer of plasmid psc101. | the rep protein, a replication initiator of plasmid psc101, also functions as an autorepressor for its own structure gene, rep, through binding to the operator which consists of imperfectly dyad-symmetric (pseudo-symmetric) sequences, ir-1 and ir-2. in order to define the dna binding motif of rep, we have analyzed its binding affinity for each half repeat of the ir sequences and found that the right half of ir-2 was the preferred sequence for rep, although its affinity was much lower than those ... | 1993 | 8276766 |
| in vivo and in vitro studies of a copy number mutation of the repa replication protein of plasmid psc101. | the repa replication protein of plasmid psc101 binds as a monomer to three repeated sequences (rs1, rs2, and rs3) in the replication origin of the plasmid to initiate duplication and binds as a dimer to two inversely repeated sequences (ir1 and ir2) in its promoter region (d. manen, l. c. upegui-gonzalez, and l. caro, proc. natl. acad. sci. usa 89:8923-8927, 1992). the binding to ir2 autoregulates repa transcription (p. linder, g. churchward, g. x. xia, y. y. yu, and l. caro, j. mol. biol. 181:3 ... | 1993 | 8320230 |
| minimal essential origin of plasmid psc101 replication: requirement of a region downstream of iterons. | the minimal replication origin (ori) of the plasmid psc101 was defined as an about 220-bp region under the condition that the rep (or repa) protein, a plasmid-encoded initiator protein, was supplied in trans. the dnaa box is located at one end of ori, as in other plasmids, like mini-f and p1. the other border is a strong binding site (ir-1) of rep which is palindromic sequence and lies in an about 50-bp region beyond the repeated sequences (iterons) in ori. this ir-1 is located just upstream of ... | 1993 | 8376344 |
| the psc101 par locus alters protein-dna interactions in vivo at the plasmid replication origin. | we report here direct evidence that mutations in the par locus affect protein-dna interactions in vivo at the replication origin of plasmid psc101. concomitant with par-mediated plasmid stabilization, two sites in the origin region show an altered methylation pattern as detected by in vivo footprinting with dimethyl sulfate. one site is located near an integration host factor-binding sequence adjacent to the first of three direct repeats known to be involved in the initiation of psc101 replicati ... | 1993 | 8376350 |
| a locus involved in the regulation of replication in plasmid psc101. | the origin of replication of plasmid psc101 contains three directly repeated sequences rs1, rs2, and rs3 separated by 22 bp from two palindromic sequences, ir1 and ir2, which are partially homologous to the direct repeats. these inverted repeat (ir) sequences overlap the promoter of the repa gene which encodes a protein essential for plasmid replication. we have shown that repa binds to the rs sites as a monomer and to the ir sites as a dimer. the influence of the ir1 site, and of the dna segmen ... | 1994 | 8022264 |
| neighboring plasmid sequences can affect mini-mu dna transposition in the absence of expression of the bacteriophage mu semi-essential early region. | bacteriophage mu dna, like other transposable elements, requires dna sequences at both extremities to transpose. it has been previously demonstrated that the transposition activity of various transposons can be influenced by sequences outside their ends. we have found that alterations in the neighboring plasmid sequences near the right extremity of a mini-mu, inserted in the plasmid psc101, can exert an influence on the efficiency of mini-mu dna transposition when an induced helper mu prophage c ... | 1994 | 8042905 |
| 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 plasm ... | 1994 | 8195072 |
| boundaries of the psc101 minimal replicon are conditional. | the dna segment essential for plasmid replication commonly is referred to as the core or minimal replicon. we report here that host and plasmid genes and sites external to the core replicon of plasmid psc101 determine the boundaries and competence of the replicon and also the efficiency of partitioning. missense mutations in the plasmid-encoded repa protein or mutation of the escherichia coli topoisomerase i gene enable autonomous replication of a 310-bp psc101 dna fragment that contains only th ... | 1995 | 7665462 |
| two enhancer elements for dna replication of psc101, par and a palindromic binding sequence of the rep protein. | the minimal replication origin (ori) of the plasmid psc101 has been previously defined as an approximately 220-bp region by using plasmids defective in the par region, which is a cis-acting determinant of plasmid stability. this ori region contains the dnaa binding sequence, three repeated sequences (iterons), and an inverted repeat (ir) element (ir-1), one of the binding sites of an initiator protein, rep (or repa). in the present study, we show that plasmids containing par can replicate at a n ... | 1995 | 7836287 |
| effects of the psc101 partition (par) locus on in vivo dna supercoiling near the plasmid replication origin. | previous work has shown that deletion of the partition (par) locus of plasmid psc101 results in decreased overall superhelical density of plasmid dna and concommitant inability of the plasmid to be stably inherited in populations of dividing cells. we report here that the biological effects of par correlate specifically with its ability to generate supercoils in vivo near the origin of psc101 dna replication. using oso4 reactivity of nucleotides adjoining 20 bp (g-c) tracts introduced into psc10 ... | 1995 | 7899092 |
| open strands adjacent to iterons promote the binding of the replication initiator protein (rep) of psc101 to the unit sequence of the iterons in vitro. | the purified dimeric form of the rep protein, a replication initiator protein of the plasmid psc101, has a low affinity for repeated sequences, iterons, in the replication origin of the plasmid, and higher affinities for two inverted repeats in the operator region of the rep gene resulting in its functioning as an autorepressor. studies of binding to various synthetic dna have established that rep can bind to duplex iteron-sequence carrying open (non-complementary) strands at one end proximal to ... | 1996 | 8597604 |
| stable high-copy-number bacteriophage lambda promoter vectors for overproduction of proteins in escherichia coli. | the construction of new high-copy-number (hcn) lambda-promoter expression vectors is described. all these vectors (1) contain tandem lambda pr and pl promoters upstream of an extensive multiple cloning site (mcs) for insertion of genes, (2) direct expression of the lambda cits857 gene, enabling their use in any escherichia coli host strain for thermal induction of gene overexpression, and (3) bear the par locus of plasmid psc101, ensuring their stable maintenance at hcn in the absence of continu ... | 1996 | 8918231 |
| characterization of copy number mutants of plasmid psc101. | we have characterized three copy number mutants of the plasmid psc101. these mutations caused single amino acid substitutions at the 46th, 83rd and 115th codons in the rep gene and an increase in the copy number by 4- to 8-fold. although the in vivo and in vitro repressor activities of these mutated rep proteins were quite different from each other, the intracellular concentrations of the proteins were maintained at higher levels than the wild-type protein. it has been reported that excess amoun ... | 1997 | 12501301 |
| dna bending of psc101 ori induced by rep, a replication initiator protein and ihf. | purified rep (or repa) protein, a replication initiator of plasmid psc101, is present almost solely in the dimer form, and its binding activity for the directly repeated sequences (iterons) in the replication origin (ori) is very low. when rep protein was treated with guanidine hydrochloride followed by renaturation, it was shown to bind to the iterons with very high efficiency. a gel shift experiment suggested that guanidine-treated rep bound to iterons as a monomer form. the rep monomer bound ... | 1997 | 12501319 |
| mechanism of recruitment of dnab helicase to the replication origin of the plasmid psc101. | although many bacterial chromosomes require only one replication initiator protein, e.g., dnaa, most plasmid replicons depend on dual initiators: host-encoded dnaa and plasmid-encoded rep initiator protein for replication initiation. using the plasmid psc101 as a model system, this work investigates the biological rationale for the requirement for dual initiators and shows that the plasmid-encoded repa specifically interacts with the replicative helicase dnab. mutations in dnab or repa that disr ... | 1999 | 9874774 |
| topology of xer recombination on catenanes produced by lambda integrase. | xer site-specific recombination at the psi site from plasmid psc101 displays topological selectivity, such that recombination normally occurs only between directly repeated sites on the same circular dna molecule. this intramolecular selectivity is important for the biological role of psi, and is imposed by accessory proteins pepa and arca acting at accessory dna sequences adjacent to the core recombination site. here we show that the selectivity for intramolecular recombination at psi can be by ... | 1999 | 10369768 |
| replacement of the bacteriophage mu strong gyrase site and effect on mu dna replication. | the bacteriophage mu strong gyrase site (sgs) is required for efficient replicative transposition and functions by promoting the synapsis of prophage termini. to look for other sites which could substitute for the sgs in promoting mu replication, we have replaced the sgs in the middle of the mu genome with fragments of dna from various sources. a central fragment from the transposing virus d108 allowed efficient mu replication and was shown to contain a strong gyrase site. however, neither the s ... | 1999 | 10482521 |
| separate roles of escherichia coli replication proteins in synthesis and partitioning of psc101 plasmid dna. | we report here that the escherichia coli replication proteins dnaa, which is required to initiate replication of both the chromosome and plasmid psc101, and dnab, the helicase that unwinds strands during dna replication, have effects on plasmid partitioning that are distinct from their functions in promoting plasmid dna replication. temperature-sensitive dnab mutants cultured under conditions permissive for dna replication failed to partition plasmids normally, and when cultured under conditions ... | 1999 | 10601213 |
| identification of the mob genes of plasmid psc101 and characterization of a hybrid psc101-r1162 system for conjugal mobilization. | similarities in dna base sequence indicate that psc101 and r1162 encode related systems for conjugal mobilization, although these plasmids are otherwise very different. the mob region of psc101 was cloned, and two genes that are required for transfer were identified. one gene, moba, encodes a protein similar in amino acid sequence to the dna processing domain of the r1162 moba protein. the other gene, mobx, is within the same transcriptional unit as the psc101 moba and is located just downstream ... | 2000 | 10940031 |
| the interaction domains of the dnaa and dnab replication proteins of escherichia coli. | the initiation of chromosome replication in escherichia coli requires the recruitment of the replicative helicase dnab from the dnabc complex to the unwound region within the replication origin oric, supported by the oric-bound initiator protein dnaa. we defined physical contacts between dnaa and dnab that involve residues 24-86 and 130-148 of dnaa and residues 154-210 and 1-156 of dnab respectively. we propose that contacts between dnaa and dnab occur via two interaction sites on each of the pr ... | 2000 | 10972842 |
| negative control of plasmid psc101 replication by increased concentrations of both initiator protein and iterons. | increased intracellular concentrations of the initiator protein rep (or repa) interfere with psc101 dna replication, and mutated rep proteins that result in an increase in plasmid copy numbers do not inhibit the replication. a rep mutant (rep(inh)) defective in the inhibitory activity was isolated and found to be a new high copy number mutant. the inhibitory function of rep was enhanced by the coexistence of directly repeated sequences (dr; iterons) in the replication origin region (ori), but no ... | 2000 | 12483601 |
| the structure and function of the replication initiator protein (rep) of psc101: an analysis based on a novel positive-selection system for the replication-deficient mutants. | plasmid psc101 encodes a 37.5 kda rep (repa) protein, which binds to three 21-base repeats (dr-1, dr-2, and dr-3) in the replication origin region (ori) of the plasmid to initiate replication. rep also binds to two palindromic sequences (ir-1 and ir-2) which overlap the rep promoter. the binding of rep to ir-2 represses the production of rep itself. it is highly likely that the balance of these functions of rep plays a major role in controlling the copy number of psc101. in this study, we develo ... | 2001 | 11530016 |
| the repa protein of plasmid psc101 controls escherichia coli cell division through the sos response. | although plasmid copy number varies widely among different plasmid species, normally copy number is maintained within a narrow range for any given plasmid. such copy number control has been shown to occur by regulation of the rate of plasmid dna replication. here we report a novel mechanism by which the psc101 plasmid also can detect an imbalance between the cellular level of its replication protein, repa, and plasmid-borne repa binding sites to inhibit bacterial dna replication and delay host c ... | 2001 | 11703672 |
| accessory factors determine the order of strand exchange in xer recombination at psi. | xer site-specific recombination in escherichia coli converts plasmid multimers to monomers, thereby ensuring their correct segregation at cell division. xer recombination at the psi site of plasmid psc101 is preferentially intramolecular, giving products of a single topology. this intramolecular selectivity is imposed by accessory proteins, which bind at psi accessory sequences and activate xer recombination at the psi core. strand exchange proceeds sequentially within the psi core; xerc first e ... | 2002 | 12110600 |
| the toxicity of recombinant proteins in escherichia coli: a comparison of overexpression in bl21(de3), c41(de3), and c43(de3). | two mutant strains of escherichia coli bl21(de3), called c41(de3) and c43(de3) and originally described by miroux and walker, are frequently used to overcome the toxicity associated with overexpressing recombinant proteins using the bacteriophage t7 rna polymerase expression system. even when the toxicity of the plasmids is so high that it prevents transformation in the strain bl21(de3), the toxic proteins can often be expressed successfully in c41(de3) and/or c43(de3). in this work, using a ran ... | 2004 | 15294299 |
| construction of highly efficient e. coli expression systems containing low oxygen induced promoter and partition region. | a series of high-copy-number escherichia coli expression vectors equipped with an oxygen-sensitive promoter p(vgb) of vitreoscilla hemoglobin (encoded by the vgb gene) were constructed and characterized. plasmid pkvp containing p(vgb) was inducible by low oxygen tension, while plasmid pkvpp containing a partition (par) region from plasmid psc101 ligated to p(vgb) provided inheritable stability for the vectors in the absence of ampicillin. plasmid pkvpv had the vitreoscilla hemoglobin operon vgb ... | 2005 | 15711794 |