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genetic analysis of the nitrogen fixation system in klebsiella pneumoniae.fine structure mapping of nif mutations of klebsiella pneumoniae was accomplished by means of pl-transductional crosses and the plasmid r144 drd mediated conjugations. the physical distance between nif mutations based on the percentage of co-transduction with hisd of the nif mutations was estimated. the maximal distance between two mutations was calculated about 3 kb, and the average distance between different nif mutations was about 1 to 2 kb. so no "silent region" was shown within the nif clus ...197724272
[expression of deo-operon escherichia coli k-12 genes in the makeup of hybrid plasmid rp4::mu-deo in pseudomonas trifolii and pseudomonas putida]. 1979113191
[transposition of chromosomal fragments of escherichia coli in plasmid rp4 by means of bacteriophage mu-1]. 1978344016
chromosomal transfer promoted by the promiscuous plasmid rp4. 1978372964
spontaneous formation of cointegrates of the oncogenic ti-plasmid and the wide-host-range p-plasmid rp4. 1978372976
spontaneous degradation of prd1 dna into unique size classes is reca dependent.the his and nif genes of the p1 type plasmid prd1 were lost at a high frequency in a reca+ but not in a reca- escherichia coli host during growth in a non-selective medium. 92% of the his- nif- segregants after 6 subcultures retained the genetic markers of the precursor plasmid rp4, while the remainder lost all of the prd1 markers with the concomitant loss of ccc-dna. plasmids purified from the his- nif- segregants resembled rp4 in the physical and genetic properties examined. the contour length ...1979375020
plasmid rp4, with escherichia coli dna inserted in vitro, mediates chromosomal transfer. 1979382198
[introduction of the bacteriophage mu into a nitrogen-fixing strain klebsiella pneumoniae m 5 a 1].mu cts 62 a thermo-inductible mutant of phage mu was integrated in e. coli in to the broad host range rp4 plasmid. the hybrid plasmid rp4::mu cts 62 was then transferred by mating to the dinitrogen-fixing strain k. pneumoniae m5al. in klebsiella mu cts 62 is still heat inducible and the phage production is similar to that observed in e. coli. mu should be a useful tool for the genetic analysis of nitrogen fixation.1976825294
plasmid rp4 as a vector replicor in genetic engineering. 19751055860
influence of glycine betaine on the transfer of plasmid rp4 between escherichia coli strains in marine sediments.the conjugative transfer of plasmid rp4 between two strains of escherichia coli in a sterile marine sediment was enhanced by the presence of glycine betaine (frequency increased 20 to 40 times). the conjugation was also facilitated by the osmoprotection of donor cells. glycine betaine is a universal osmolyte and has been found in marine sediments at high concentrations. so this phenomenon could have epidemiological and sanitary importance by increasing the possibility of dissemination of some pl ...19901366575
[mu-induced deletions and mutations of erwinia carotovora chromosomes, including resident prophages e105 and 59].the plasmid rp4::mu cts62 in stably inherited by erwinia carotovora 268 strain. under the conditions of thermoinduction bacteriophage mu is segregated and completely eliminated more intensively than in escherichia coli cells. at thermoinduction the transposition of bacteriophage mu cts62 into different chromosomal sites takes place, causing the induction of chlorate resistant and auxotrophic mutants with the frequency of 10(-4). two clones deficient in production of 2 of the 4 resident prophages ...19921406759
regional specificity of illegitimate recombination by the translocatable ampicillin-resistance element tn1 in the genome of phage p22.insertions of the translocatable ampicillin-resistance element tn1 were selected in the genome of the temperate salmonella phage p22 by growing the phage on hosts carrying the resistance plasmid rp4. insertions of tn1 into phage p22 are rare (10(-10) per phage) and nonrandomly distributed in the p22 genome. they are found mainly in the vicinity of the p22 ant gene. insertions within the ant gene are found at many (at least 15) genetically separable sites, are found equally frequently in both ori ...1979395016
transfection and transformation of agrobacterium tumefaciens.the freeze thaw transfection procedure of dityatkin et al. (1972) was adapted for the transfection and transformation of a. tumefaciens. transfection of the strains b6s3 and b6-6 with dna of the temperate phage ps8cc186 yielded a maximum frequency of 2 10(-7) transfectants per total recipient population. in transformation of the strain gv3100 with the p type plasmid rp4 a maximum frequency of 3.5 10(-7) transformants per total recipient population was obtained. agrobacterium ti-plasmids were int ...1978355847
[isolation of nontransmissible deletion variants and the genetic map of pas8 plasmid (rp4-cole1)]. 1977348571
korb protein of promiscuous plasmid rp4 recognizes inverted sequence repetitions in regions essential for conjugative plasmid transfer.we have constructed a rp4 korb overproducing strain and purified the protein to near homogeneity. korb is a dna binding protein recognizing defined palindromic 13-bp sequences (tttagcsgctaaa). inverted sequence repetitions of this type, designated ob, are present on rp4 12 times. ob-sequences are localized in replication and maintenance regions as well as in the regions tra1 and tra2 essential for conjugative transfer. all sites found in tra regions by computer search act as targets for specific ...19921579485
suppressor mutation in pseudomonas aeruginosa.suppressor mutations were identified in pseudomonas aeruginosa, and a comparison was made with escherichia coli suppressor systems. a suppressor-sensitive (sus) derivative of a plasmid, rp4 trp, and several sus mutants of incp1 plasmid-specific phages, were isolated by using e. coli. plasmid rp4 trp (sus) was transferred to p. aeruginosa strains carrying trp markers which did not complement rp4 trp(sus), and trp+ variants were selected. some, but not all such revertants, could propagate prd1 sus ...1979110767
[effect of plasmid f'col+trp+ on the transfer of plasmid rp4].interaction of conjugative plasmids f'colv colb trp and pr4 in escherichia coli host was studied during the transfer of the plasmids from cell to cell. the plasmid f'colv colb trp is found to stimulate the transfer of rp4 from the diplasmid strain. this seems to be due to stabilization of the conjugating pairs which require normal pili coded by the plasmid f'colv colb trp.197941796
the divergent promoters mediating transcription of the par locus of plasmid rp4 are subject to autoregulation.the partitioning region of broad-host-range plasmid rp4 contains four genes (para, parb, parc, and pard) that encode products essential for partition activity. two divergently arranged promoters located in the intercistronic region between parc and pard mediate transcription of these genes. the transcriptional initiation sites for both promoters were determined by primer extension. transcriptional fusions were used to show that para, parb, and parc are combined in an operon, while pard constitut ...19921508044
[conjugative transfer of plasmid dna between bacteria in soil].conjugative transfer of plasmid rp4 between populations of azospirilla and between escherichia coli and azospirillum brasilense in nonsterile soil has been investigated. the process of genetic exchange was realized at the early stages of interpopulational interactions, further on the process intensity was obviously rather low. population dynamics of azospirilla transconjugates in soil depends on the presence or the absence of additional food substrate.19921474945
a thiostrepton-inducible expression vector for use in streptomyces spp.a shuttle expression vector containing the thiostrepton-inducible streptomyces lividans promoter, ptipa, and the origin of transfer from plasmid rp4 was constructed. cassettes containing a promoterless xyle gene upstream from a hyg gene were used to demonstrate thiostrepton-inducible expression from ptipa in both s. lividans and streptomyces ambofaciens, ptipa was estimated to be induced 60-fold or more in streptomyces ambofaciens.19911879704
sequence similarities between the rp4 tra2 and the ti virb region strongly support the conjugation model for t-dna transfer.transfer genes of the incp plasmid rp4 are grouped in two separate regions, designated tra1 and tra2. tra2 gene products are proposed to be mainly responsible for the formation of mating pairs in conjugating cells. to provide information relevant to understanding the function of tra2 gene products, the nucleotide sequence of the entire rp4 tra2 region is presented here. twelve open reading frames were identified in the tra2 core region, being essential for intraspecific escherichia coli matings. ...19921400366
competition between strains of escherichia coli with and without plasmid rp4 during chemostat growth.escherichia coli strains j53(nal) and j53(rp4) were grown together in glucose-limited continuous cultures. based on the measured growth kinetic constants of the two strains, take-over of the cultures by j53(rp4) was predicted. however, in practice, an initial period of predominance by j53(rp4) was always followed by a prolonged period in which relative numerical proportions of the two strains oscillated widely. this period of oscillation was removed or greatly reduced when the difference between ...19911913355
sequence analysis and characterization of the mobilization region of a broad-host-range plasmid, ptf-fc2, isolated from thiobacillus ferrooxidans.the nucleotide sequence of a 5,317-bp fragment which includes the region required for mobilization of broad-host-range plasmid ptf-fc2 was determined. a region of approximately 3.5 kb was required for plasmid mobilization, and orit was localized on a 138-bp fragment. polypeptides which corresponded in size and location to several of the open reading frames were detected in an in vitro transcription-translation system. three open reading frames essential for plasmid mobilization and two which aff ...19921400173
virulence plasmid pjm1 prevents the conjugal entry of plasmid dna into the marine fish pathogen vibrio anguillarum 775.studies involving the introduction of cloned homologous genes into vibrio anguillarum revealed that several plasmids could not be conjugally introduced into v. anguillarum 775(pjm1), but were transmissible to the pjm1-cured derivative h775-3. recombinant pbr322 plasmids containing v. anguillarum genomic dna inserts were mobilized from escherichia coli donors, using prk2013, into v. anguillarum h775-3 recipients at frequencies of 10(-6) to 10(-5) per recipient. when identical matings were perform ...19921336793
mechanism of integration of the broad-host-range plasmid rp4 into the chromosome of myxococcus xanthus.the site-specific recombination mechanism through which the plasmid rp4 has been previously shown to integrate into the chromosome of myxococcus xanthus has been investigated further. once integrated in one of the numerous chromosomal sites from two different strains, through a precise site on the plasmid, the latter can be excised either precisely or after a definite 14.5-kb deletion. in some cases, the integration is followed by different dna rearrangements that yield a higher rate of excision ...19902120716
a directional, high-frequency chromosomal mobilization system for genetic mapping of rhizobium meliloti.a system for mapping of the rhizobium meliloti chromosome that utilizes transposon tn5-mob, which carries the mobilization site of incp plasmid rp4 (r. simon, mol. gen. genet. 196:413-420, 1984), was developed. insertions of tn5-mob that were located at particular sites on the r. meliloti chromosome were isolated and served as origins of high-frequency chromosomal transfer when incp tra functions were provided in trans. this approach is, in principle, applicable to any gram-negative bacterium in ...19921309521
conjugation in agrobacterium tumefaciens in the absence of plant tissue.a general, reliable conjugation system for agrobacterium tumefaciens in the absence of plant tissue is described in which a. tumefaciens can serve either as the donor or recipient of plasmid deoxyribonucleic acid with reasonable efficiency. plasmid rp4 was transferred from escherichia coli to a. tumefaciens and from strain of a. tumefaciens. both rp4 and the a. tumefaciens virulence-associated plasmids were detected by alkaline sucrose gradients in a. tumefaciens strains a6 and c58 after mating ...1976783141
[expression of the gene for tetracycline resistance of plasmids r6 and rp4 in bacteria of the family enterobacteriaceae].it was found that manifestation of the tetracycline resistance gene depended on the type of the plasmid containing the gene. the tetracycline resistance gene was subject to less repression in plasmid r6 than in plasmid rp4. sensitivity of the initial plasmid-free bacteria varied within lower dose ranges than that of the plasmid-carrying strains. regulation of the tetracycline resistance gene manifestation in the given plasmid may change in different bacterial hosts, i.e. in different cytoplasmic ...1979375821
properties of r plasmid r772 and the corresponding pilus-specific phage pr772.r plasmid r772 was isolated from a strain of proteus mirabilis and is a self-transmissible p-1 incompatibility group plasmid having a molecular weight of about 27 x 10(6). it renders bacterial hosts resistant to kanamycin. phage pr772 was isolated as a phage dependent on the presence of r772 in bacterial hosts. it is hexagonal-shaped with a diameter of 53 nm, has a thick inner membrane and no tail. vaguely defined appendages are sometimes apparent at some vertices and the phage possesses double- ...1979374677
a gene near the plasmid psa origin of replication encodes a nuclease.we have cloned and sequenced a gene (nuc) from the incw plasmid psa which shows amino acid sequence similarity to staphylococcal nuclease (ec 3.1.4.7) and to the parb locus of plasmid rp4. the 525 bp open reading frame encodes a 174-amino-acid potential polypeptide of 19.7 kda. expression of the gene was confirmed using an in vitro transcription-translation assay which produced a protein of identical size. nuclease activity was demonstrated using dna as the substrate in toluidine blue-dna agar p ...19921560781
[erwinia carotovora as a recipient system for the natural hybrid plasmid rp4::mu cts62].the plasmid rp4::mu cts62 is transferred from escherichia coli cells into a recipient strain erwinia carotovora 268 by conjugation with the frequency 1.5-5 x 10(-7) per donor cell. the maximal frequencies of transfer are obtained by cultivation of donor and recipient cells for 3-5 h on the filters. structural and functional validity of the plasmid in transconjugants is expressed in preservation of all antibiotic-resistant markers of rp4, thermosensitivity to growth at 42 degrees c as well as spo ...19902175013
transposon-mediated insertion of r factor into bacterial chromosome.insertion of transposon t n1 into the e. coli jc411 chromosome results in a sharp increase of plasmid rp4 integration frequency. this effect is absent in jc1553 reca cells. the rp4 integration with the chromosome is probably accomplished via reca-dependent recombination between transposon tn1 inserted into the chromosome and the same transposon in the rp4 plasmid.1978353520
a natural mutant of plasmid rp4 that confers phage resistance and reduced conjugative transfer.a natural isolate of rp4 (prc#116) acquired from the stanford university plasmid reference center differed from the wild-type incompatibility group p plasmid in several respects. cells of escherichia coli harboring prc#116 were resistant to the incp pili-specific bacteriophage prd1 and gu5, and transferred this plasmid at a lower efficiency than the wild-type rp4. phage sensitivity was restored, and transfer considerably improved in prc#116+ bacteria transformed with plasmid constructs containin ...19921587464
conjugal transfer system of plasmid rp4: analysis by transposon 7 insertion.we have begun an analysis in escherichia coli of the conjugal transfer functions of the broad-host-range plasmid rp4. we have isolated 19 tra mutants of rp4, generated by insertion of transposon 7, and mapped their insertion sites by restriction endonuclease analysis. these sites fall into two separate regions on either side of the kanamycin resistance determinant. the transfer rates of the mutants range from 10% of that of rp4 to an undetectable level. spot tests with the p-1 pilus-specific pha ...1978338595
[isolation of transmissible cointegrates of yersinia pestis plasmids pyv and pyt with the plasmid rp4::mu cts 62, incp1].the transmissible cointegrates of the yersinia pestis plasmids pyv and pyt with the broad host range plasmid rp4::mu cts62 of the incompatibility group incp have been constructed by the in vivo recombination. the cointegrative plasmid pkr14 (pyv76 omega rp4::mu cts62) conferred on the transconjugants the properties of ca2(+)-dependence at 37 degrees c, v-antigen synthesis, rp4 plasmid markers (apr, kmr, tcr), immunity to the lysis by the bacteriophage mu cts62 and incompatibility with the homolo ...19902233780
[transposition of the deo operon structural genes in escherichia coli k-12 to plasmid rp4 using bacteriophage mu].transposition of the structural genes of the deo operon of escherichia coli k-12 into plasmid rp4 by means of temperate bacteriophage mu was carried out. some variants of composite rp4-deo-mu plasmids were obtained and the expression of the deo genes integrated into the rp4 plasmid genome was studied. it was shown that the expression of these genes remains under the control of the chromosomal regulatory genes (deor and cytr); although the activity of thymidine phosphorilase in the strain e. coli ...1979157908
[change in the ultrastructure of the cell wall of bacillus cereus, determined by rp4 mucts62 plasmid].the influence of plasmid rp4 mucts62, heterologous for b. cereus, on the growth rate of b. cereus strains ga 682 and 319 obtained in our earlier experiments and on changes in the ultrastructure of their cell walls in comparison with b. cereus initial strains gp 7 and dsm 318 has been studied. plasmid rp4 mucts62 with a wide spectrum of action has been found not only to determine the functional signs of resistance to antibiotics and thermal sensitivity in the heterologous host, but also to take p ...19892499144
trak protein of conjugative plasmid rp4 forms a specialized nucleoprotein complex with the transfer origin.conjugative transfer of the self-transmissible incp plasmid rp4 requires the product of the rp4 trak gene. by using the phage t7 expression system, the trak gene product was efficiently overproduced and purified to near homogeneity. trak encodes a basic protein (pi = 10.7) of 14.6 kda that, as shown by dna fragment retention assay, interacts exclusively with its cognate transfer origin. the apparent equilibrium constant k(app) for the complex of trak and orit-dna was estimated to be 4 nm. footpr ...19921324929
establishment of gene transfer systems for and construction of the genetic map of a marine vibrio strain.two gene transfer systems were established for a marine bacterium, vibrio sp. strain 60. one was generalized transduction with a newly isolated bacteriophage, as3, and the other was conjugal gene transfer by the use of newly constructed transposon-facilitated recombination (tfr) donors. as3 transduced various chromosomal markers at frequencies of 10(-4) to 10(-6). tfr donors, which were constructed by introducing transposon tn10 into both plasmid rp4 and the chromosome, mediated the polarized tr ...19892539353
isr1, a transposable dna sequence resident in rhizobium class iv strains, shows structural characteristics of classical insertion elements.isr1 is a small transposable element, identified in rhizobium class iv strains by its high frequent mutagenic insertion into plasmid rp4. hybridization studies showed that isr1 is present in, multiple copies in rhizobium class iv strains. nucleotide sequence analysis revealed that isr1 has a length of 1260 bp and is characterized by perfect inverted repeats of 13 nucleotides followed by a stretch of 28/29 nucleotides with imperfect homology. the insertion under study generated a target site dupl ...19892544911
direct selection for curing and deletion of rhizobium plasmids using transposons carrying the bacillus subtilis sacb gene.we have constructed derivatives of the transposon tn5 carrying the mob site (orit) of plasmid rp4, and an npti-sacb-sacr cassette [ried and collmer, gene 57 (1987) 239-246]. the mob site, in conjunction with the antibiotic-resistance markers carried on the transposons, allows identification of transposon inserts in cryptic plasmids by mobilisation to other strains. the sacb-sacr genes allow direct selection for the loss or curing of plasmids, because only strains which no longer contain an activ ...19892548927
anaerobic growth of escherichia coli on glycerol by importing genes of the dha regulon from klebsiella pneumoniae.the dha regulon of klebsiella pneumoniae specifying fermentative dissimilation of glycerol was mobilized by the broad-host-range plasmid rp4:mini mu and introduced conjugatively into escherichia coli. the recipient e. coli was enabled to grow anaerobically on glycerol without added hydrogen acceptors, although its cell yield was less than that of k. pneumoniae. the reduced cell yield was probably due to the lack of the coenzyme-b12-dependent glycerol dehydratase of the dha system. this enzyme in ...19892559947
[transmissible hybrid plasmid rp4-cole1].hybrid plasmid rp4-cole1 was obtained by joining dna plasmids rp4 and cole1, each of which possessed only one site of restriction for ecor1. these plasmid molecules were restricted by endonuclease ecor1 and then treated by ligase. the hybrid plasmid retained the property of transmissibility typical for drug factor resistance rp4. non-transmissible mutant of the hybrid plasmid selected by the character of the resistance of escherichia coli c600 (rp4-cole1) to the phage prr1 is used for subsequent ...1976795717
fertility inhibition in rhizobium lupini by the resistance plasmid rp4.r plasmid rp4 inhibits the fertility of r. lupini. an rp4 carrying r. lupini donor strain is no longer capable of transferring chromosomal genes. after loss of rp4 the r. lupini fertility reappears. plasmid rp4 spontaneously mutates at high frequency in r. lupini. rp4 mutants which do not inbibit fertility were isolated. these mutants were always transfer-defective, too. it is postulated that the genetic information for fertility inhibition in r. lupini is a substantial part of the transfer unit ...1978672901
r-plasmid-mediated chromosomal gene transfer in agrobacterium tumefaciens.although several techniques are available for transferring the ti plasmids from one strain of agrobacterium tumefaciens to another, there are no reproducible methods for analysis of chromosomal markers in this phytopathogen. the r plasmid, r68.45, is known to show chromosomal mobilizing ability in several bacterial genera including the closely related rhizobia. r68.45 was transferred into the prototrophic a. tumefaciens strain 15955. ten kanamycin-resistant transconjugant clones were tested for ...1979457601
dissection of incp conjugative plasmid transfer: definition of the transfer region tra2 by mobilization of the tra1 region in trans.we constructed a transfer system consisting of two compatible multicopy plasmids carrying the transfer regions tra1 and tra2 of the broad-host-range incp plasmid rp4. in this system, the plasmid containing the tra1 region with the origin of transfer (orit) was transferred, whereas additional functions essential for the conjugative process were provided from the tra2 plasmid in trans. the tra2 region, as determined for matings between escherichia coli cells, maps between coordinates 18.03 and 29. ...19921556069
map of plasmid rp4 derived by insertion of transposon c. 1977328901
mini-mu transposition of bacterial genes on the transmissible plasmid.using the prm30 plasmid, an aps deletion derivative of broad host range plasmid rp4 with integrated new minimu 5 (11 kb), we followed the transfer of escherichia coli chromosomal genes to the recipient strain. the minimu 5-mediated transposition of chromosomal genes occurs onto the plasmid with integrated minimu 5 rather than onto the "recipient" plasmid pnh602. the plasmid dna in recipient cells was detected by electrophoresis. one of the acquired hybrid plasmids ptb2 was analyzed genetically a ...19872826318
in vitro insertion of the lambda attachment site into the plasmid rp4.the region of the phage lambda chromosome containing the attachment site (p.p') and the genes int and xis, excised by the action of endonuclease r.ecori, has been inserted into the unique site for that enzyme on the promiscuous conjugative plasmid, rp4, generating the recombinant plasmid rp4att lambda. transformants containing the hybrid plasmid were recognised by their ability to allow efficient lysogenization by phage lambda b2 (weil and signer, 1968; echols et al., 1968) containing the mutant ...1979231725
acquisition of a sucrose utilization system in escherichia coli k-12 derivatives and its application to industry.an escherichia coli strain, b-62, that was isolated from a clinical source and was epidemiologically unrelated to e. coli k-12 was the source of chromosomal dna for a sucrose utilization system (scr+) in the construction of a plasmid, pst621. the cloned insert of a gene encoding scr+ in pst621 conferred a sucrose-positive phenotype onto transformed cells of e. coli k-12 derivatives. sucrase activity of the transformants was as high as that which would correspond to a "gene dosage effect" of a ve ...19921622287
nucleotide sequence and organization of genes flanking the transfer origin of promiscuous plasmid rp4.the nucleotide sequence of the relaxase operon and the leader operon which are part of the tra1 region of the promiscuous plasmid rp4 was determined. these two polycistronic operons are transcribed divergently from an intergenic region of about 360 bp containing the transfer origin and six close-packed genes. a seventh gene completely overlaps another one in a different reading frame. conjugative dna transfer proceeds unidirectionally from orit with the leader operon heading the dna to be transf ...19911665997
characterization and classification of actinobacillus (haemophilus) pleuropneumoniae plasmids.actinobacillus (haemophilus) pleuropneumoniae plasmids were characterized and classified. they were isolated from a pleuropneumoniae strains different in serotype, year isolated, or location from which isolated. six of 8 plasmids encoded streptomycin (sm) and sulfonamide (su) resistance (smsu). one of the other plasmids, pvm105, encoded ampicillin (ap) resistance and another, phm0, encoded no drug resistance. all smsu plasmids were transferred to escherichia coli strains by transformation. among ...19911785724
electroporation and conjugal plasmid transfer to members of the genus aquaspirillum.electroporation methods and conjugal matings were used to transfer several plasmid vectors to aquaspirillum dispar and aquaspirillum itersonii. the incompatibility p class plasmid rp4 was conjugally transferred from escherichia coli hb101 to these spirilla, and the transconjugants subsequently donated the molecule to plasmid-free e. coli and a. dispar strains via conjugal matings. high-voltage electrotransformation was used to transfer plasmids pucd2, psa151 and rp4 to a. dispar and a. itersonii ...19911907445
transfer of incp plasmids into stigmatella aurantiaca leading to insertional mutants affected in spore development.derivatives of the broad-host-range plasmid rp4, containing the wild-type or modified transposon tn5 were transferred by conjugation to various stigmatella aurantiaca isolates. the transposons and in some cases fragments of the plasmid as well were integrated into the chromosome. thus, insertional mutants have been obtained affected in spore formation in liquid culture.19882853291
construction of a mobilizable cloning vector for site-directed mutagenesis of gram-negative bacteria: application to rhizobium leguminosarum.a mobilizable cloning vector was constructed from defined fragments to serve as a suicide plasmid for site-directed mutagenesis. the new vector, pkok4, closely resembles plasmid pbr325. however, the inverted duplication existing in the latter was not introduced. the useful cloning sites of pbr325 (ecori, hindiii, ecorv, bamhi, sali, psti and pvui) were retained and are located in one of the three resistance markers, apr, cmr or tcr, respectively. also, in pkok4 the cmr gene retains its own promo ...19912013412
[the genetic transfer, heredity and phenotypic expression of plasmid rp4::mu cts genes in bacillus cereus].the transcipients were obtained in intrageneric matings of e.coli donor harbouring the plasmid pr4::mu cts 62 with bac. cereus gp7 recipient cells with the frequency 10(-9). the transcipient clone bac. cereus 682 was selected having stably inherited and expressed the hybrid plasmid pr4::mu cts 62 genes for antibiotic resistance and temperature sensitivity. production of the bacteriophage mu cts 62 particles was not registered in the bacillary transcipient cells. the plasmid rp4::mu cts 62 genes ...19902114185
[transfer of prophage mu into methylotrophic bacteria in the plasmid rp4].bacteriophage mu genome has been transferred into the cells of pseudomonas methanolica and methylobacterium sp. skf240, that are naturally resistant to the bacteriophage, as a fragment of a hybrid plasmid rp4::mu cts62. temperature induction of the bacteriophage results in host cell lysis. plasmid rp::mu cis62 is maintained in methylotrophic cells presenting a cointegrative structure. the genetic and electrophoretic, analyses of the dna isolated from transconjugant cells have confirmed the concl ...19852948119
the dehalogenase gene dehi from pseudomonas putida pp3 is carried on an unusual mobile genetic element designated deh.as a result of the production of two dehalogenases (dehi and dehii), pseudomonas putida pp3 utilized halogenated alkanoic acids, such as 2-monochloropropionic acid (2mcpa), as sole sources of carbon and energy. the dehi gene (dehi) was carried on a mobile genetic element (deh) located on the chromosome of strain pp3. deh recombined with target plasmid dnas at high frequencies (e.g. 3.8 x 10(-4) per rp4.5 plasmid transferred). the regulated expression of dehi was detected in p. putida, pseudomona ...19921312533
plasmid rp4 host-lethal function kila and its repressor kora sequences are part of the cryptic tellurite resistance transposon tn521.the normally silent 4.5 kb tellurite resistance transposon tn521 of rp4 has been shown to carry sequences from both the flanking kila and kora loci of this broad host range plasmid. the major portion of both of these sequences were used as probes to examine dna homology in southern transfer hybridization experiments with plasmid recipients of tn521 chosen from varying incompatibility groups. in the case of every recipients molecule analyzed using either probe, dna homology was observed.19902165965
covalent association of the trai gene product of plasmid rp4 with the 5'-terminal nucleotide at the relaxation nick site.formation of relaxosomes is the first step in the initiation of transfer dna replication during bacterial conjugation. this nucleoprotein complex contains all components capable of introducing a site- and strand-specific nick at a cognate transfer origin (orit) on supercoiled plasmid dna, thus providing the substrate for generation of the strand to be transferred. characterization of the terminal nucleotides at the orit nick site revealed that relaxation occurs by hydrolysis of a single phosphod ...19902191955
transfer of transposable drug-resistance elements tn5, tn7, and tn76 to azotobacter beijerinckii: use of plasmid rp4::tn76 as a suicide vector.transposable elements tn5, tn7, and tn76 were transferred to azotobacter beijerinckii. evidence was obtained for the transposition of tn5 but cells of the majority of presumptive transposition isolates had abnormal morphologies and rapidly lost viability when subcultured. data are presented that indicate that plasmid rp4::tn76 behaves as a suicide vector upon transfer to this host, allowing the isolation of a. beijerinckii::tn76 isolates at a high frequency. nitrogen-fixing mutants and leucine a ...19852999852
mobilization of escherichia coli r1 silver-resistance plasmid pjt1 by tn5-mob into escherichia coli c600.escherichia coli r1 is an ag(+)-resistant strain that, as we have shown recently, harbours at least two large plasmids, pjt1 (83 kb) and pjt2 (77 kb). tn5-mob was introduced into the e. coli r1 host replicon via conjugation on membrane filters. the transfer functions of plasmid rp4-4 were provided in this process and tn5-mob clones mated with e. coli c600 yielded ag(+)-resistant transconjugants. this mobilization procedure allowed transfer and expression of pjt1 ag+ resistance in e. coli c600. p ...19902169281
[the multiple effect of plasmid rp4::mu cts 62 in transcipient bacilli].transfer of conjugative hybrid plasmid rp4::mu cts 62 from escherichia coli into bac. cereus, bac. thuringiensis, bac. mesentericus and bac. polymyxa cells led to the multiple effects on the structure and physiology of bacillus cells. it has resulted in a decrease of the bacillus vitality, in the accelerated autolytic decay of cells, in the delay of cell growth and reproduction rate in liquid and solid media, in the disruption of ultrastructure of the cell membrane and its surface layer.19902273994
vibrio cholerae hybrid sex factor that contains ampicillin transposon tn1.the ampicillin resistance transposon tn1 was translocated from the r plasmid rp4 to the vibrio cholerae conjugative plasmid, p. the hybrid sex factor p::tn1 was highly transmissible and expressed the biological activities of the p factor. in addition, p::tn1 facilitated transfer of rp4 to v. cholerae recipients. physical studies of p::tn1 indicated that the tn1 transposon was added to the otherwise unaltered p plasmid.1979253004
in vitro assembly of relaxosomes at the transfer origin of plasmid rp4.during initiation of conjugative transfer of dna containing the transfer origin (orit) of the promiscuous plasmid rp4, the proteins trai, traj, and trah interact and assemble a specialized nucleoprotein complex (the relaxosome) at orit. the structure can be visualized on electron micrographs. site- and strand-specific nicking at the transfer origin in vitro is dependent on the proteins trai and traj and on mg2+ ions. substrate specificity is directed exclusively towards the cognate transfer orig ...19902168553
partitioning of broad-host-range plasmid rp4 is a complex system involving site-specific recombination.the broad-host-range plasmid rp4 encodes a highly efficient partitioning system (par) that was previously mapped within the 6.2-kb psti c fragment. the essential functions were assigned to a region of 2.2 kb between fiwa and is21 (is8). on the basis of the nucleotide sequence data of the entire par locus and of in vitro and in vivo expression studies, three distinct loci encoding polypeptides of 9, 18, and 24 kda were identified. evidence for the expression of another polypeptide was found. a pu ...19902172207
traj protein of plasmid rp4 binds to a 19-base pair invert sequence repetition within the transfer origin.transfer of plasmid rp4 during bacterial conjugation requires the plasmid-encoded traj protein, which binds to the transfer origin (fürste, j. p., pansegrau, w., ziegelin, g., kröger, m., and lanka, e. (1989) proc. natl. acad. sci. u.s.a. 86, 1771-1775). as indicated by traj mutants, the traj protein is a constituent of the relaxosome, the initiation complex of transfer dna replication. the traj gene maps adjacent to the transfer origin (orit). the structural gene consists of a 372-base pair seq ...19892663846
conjugative transfer of promiscuous incp plasmids: interaction of plasmid-encoded products with the transfer origin.to characterize protein-dna interactions involved in the initiation of conjugative transfer replication, we isolated and sequenced the transfer origins (orit) of the promiscuous incp plasmids rp4 and r751. the central initiating event at the transfer origin of a conjugative plasmid is the cleavage at a unique site (nic) of the strand to be transferred to a recipient cell. this process can be triggered after the assembly of "relaxosomes" (plasmid dna-protein relaxation complexes), requiring plasm ...19892538813
[structural-functional organization of r-plasmid pbs222 with a broad range of bacterial hosts].the broad host-range plasmid pbs222 is compatible with broad host-range plasmids of all known incompatibility groups and codes for tetracycline resistance. pbs222 is efficiently mobilized by inc p-1 plasmid rp4 and is also capable of conjugal transfer with low efficiency to different gramnegative microorganisms. the size of the plasmid (17.2 kb) has been determined and its physical map has been constructed. the plasmid harbours the unique sites for restriction endonucleases bglii, hindiii, hpai, ...19863027554
cloning of the cyo locus encoding the cytochrome o terminal oxidase complex of escherichia coli.the structural genes encoding the cytochrome o terminal oxidase complex (cyo) of escherichia coli have been subcloned into the multicopy plasmid pbr322 after the mu-mediated transposition of the gene locus from the bacterial chromosome onto the conjugative r plasmid rp4. introduction of cyo plasmids into strains (cyo cyd) lacking both terminal oxidases restored the ability of the strains to grow aerobically on nonfermentable substrates. strains carrying the cyo plasmids produced 5 to 10 times mo ...19873036778
[interaction of yersinia pestis bacteria with bacteriophage mu].yersinia pestis cells are shown to be sensitive to bacteriophage mu cts62 infection. lysis of bacteria has been shown to be more efficient on solid nutrient medium than in lb broth. 10(-5) pfu per ml is the maximal concentration of bacteriophage particles yielded from the broth cultures of bacteria. moi 0.1 has been used to obtain such yields of bacteriophage. lysogenization of yersinia pestis cells has not been achieved when the standard methods of bacteriophage infection have been used. it was ...19852948125
two mechanisms necessary for the stable inheritance of plasmid rp4.plasmid rp4 is stably maintained in strains of escherichia coli and other gram-negative bacteria. inactivation of the plasmid primase gene (pri) or removal of the pstic fragment gave rp4 derivatives that are slightly unstably maintained in e. coli. removal of the tn 1 multimer resolution system (res and tnpr) did not lead to any detectable plasmid loss. removal of all three of these regions, however, gave rise to pnj5000 which is lost at high frequency. we have dissected the mechanisms causing t ...19892699039
effects of lincomycin on synthesis of tem beta-lactamase by escherichia coli.sub-inhibitory concentrations of lincomycin slightly inhibit growth of escherichia coli carrying plasmid rp4 and cause a 2-fold increase in tem-2 beta-lactamase. to analyze this effect, cultures were pulse-labeled with [3h]leucine, chased with non-radioactive leucine and immunoprecipitated with anti-beta-lactamase antiserum. the synthesis rate of beta-lactamase was two times higher in inhibited cultures than in control cultures. no significant decrease of labeled enzyme occurred during the 30 mi ...19883290174
lack of expression of rp4-specified beta-lactamase in azospirillum brasilense.plasmid rp4, which normally confers resistance to ampicillin (apr), tetracycline (tcr), and kanamycin (kmr) to its hosts, failed to express enhanced apr when transferred from escherichia coli to azospirillum brasilense which has its own intrinsic beta-lactamase. even in a beta-lactamase-deficient mutant, a. brasilense rg-d16, no increase in beta-lactamase or significant apr appeared following transfer of rp4. however, a. brasilense rg (rp4) and a. brasilense rg-d16 (rp4) did exhibit tcr kmr. whe ...19892699042
cloning and analysis of rfb gene synthesizing the mannan 0 side chain of escherichia coli 09 lipopolysaccharide.the rfb gene encoding the proteins responsible for the synthesis of the repeating units (o side-chain) of escherichia coli 09 lipopolysaccharide was cloned into a conjugative plasmid rp4::minimu and was expressed in e. coli k-12.19902183549
[sos-induction of the rp4 plasmid tet-determinant].induction of the tetracycline-resistance genes function by the inducer of the dna-repair and mutability sos-system, uv-light, has been tested. activity of the tet-genes residing on the plasmid rp4 in escherichia coli cells has been shown to be inducible by the low doses of tetracycline as well as by the mutagenic doses of uv-light. the induction was quantitatively registered by measuring the activity of beta-galactosidase of bacteriophage mud1 (ap, lac) inserted into the tet-genes of the plasmid ...19882848194
transfer and properties of some natural and suicide replicons in pasteurella multocida.we tested the transfer of several plasmids and transposons from escherichia coli to pasteurella multocida by filter mating. two plasmids, prktv5 (prk2013::tn7) and puw964 (prktv5::tn5), were derived from prk2013--a narrow-host-range plasmid with the broad-host-range incp conjugation genes. most p. multocida transconjugants obtained with prktv5 had tn7 insertions in the chromosome but some had insertions of the whole plasmid. by contrast, all the transconjugants obtained with puw964 had insertion ...19892561489
role and specificity of plasmid rp4-encoded dna primase in bacterial conjugation.the role of the dna primase of incp plasmids was examined with a derivative of rp4 containing tn7 in the primase gene (pri). the mutant was defective in mediating bacterial conjugation, with the deficiency varying according to the bacterial strains used as donors and recipients. complementation tests involving recombinant plasmids carrying cloned fragments of rp4 indicated that the primase acts to promote some event in the recipient cell after dna transfer and that this requirement can be satisf ...19863522540
mode of insertion of the broad-host-range plasmid rp4 and its derivatives into the chromosome of myxococcus xanthus.the mode of insertion of the broad-host-range plasmid rp4 into the chromosome of myxococcus xanthus strain dz1 has been analyzed. the plasmid integrated in numerous sites of the chromosome and generated insertional mutations. there is a hot spot of integration located between 31.5 and 34.5 kb clockwise from the ecori site of the plasmid. in the absence of this segment the insertion can, however, take place, but much less efficiently. the presence of transposable elements on the plasmid decreases ...19872829249
[the infection of bacilli by mu cts phage integrated into the plasmid].the infection of bacillus thuringiensis, b. cereus, b. mesentericus and b. polymyxa strains with temperate e. coli bacteriophage mu cts62 integrated into plasmid rp4 under conditions of conjugative transfer is shown possible. the investigated strains of bacilli are not able to produce intact phage particles but they acquire the thermosensitive property determined by the phage genome. gel electrophoresis and blot hybridization of dna have confirmed the transfer of mu cts62 genome or a part of it ...19902145498
genetic analysis of tn7 transposition.the purpose of this work was to localize the dna regions necessary for the transposition of tn7. several deletions of tn7 were constructed by the excision of dna fragments between restriction sites. the ability of these deleted tn7s to transpose onto the recipient plasmid rp4 was examined. all the deleted tn7s isolated in this work had lost their transposing capability. the possibility of complementing them was studied using plasmids containing all or part of tn7. two deleted tn7s could not be c ...19852984518
silver accumulation and resistance in escherichia coli r1.e. coli r1 contains at least 2 large plasmids (83 and 77 kb) while e. coli s1 was previously cured of the 83 kb plasmid. transformation using artificial competence, high-voltage electroporation, and plasmid mobilization experiments with the mobilizing plasmid rp4, failed to ascertain the 83 kb plasmid was responsible for ag(+)-resistance. silver accumulation by an ag(+)-sensitive e. coli s1 strain was 5-fold higher than an ag(+)-resistant e. coli r1 strain. the ag(+)-resistant e. coli r1 strain ...19902202786
nucleotide sequence of the kanamycin resistance determinant of plasmid rp4: homology to other aminoglycoside 3'-phosphotransferases.the kanamycin resistance determinant of the broad-host-range plasmid rp4 encodes an aminoglycoside 3'-phosphotransferase of type i. the nucleotide sequence of the kanamycin resistance gene (kmr) and the right end of the insertion element is8 of plasmid rp4 has been determined. the gene (816 bp) is located between is8 and the region (tra 1) encoding plasmid factors mediating bacterial conjugation. kmr and tra 1 are transcribed toward each other. the nucleotide sequence has been compared to five r ...19872832861
trimethoprim resistance plasmids in escherichia coli isolated from cases of diarrhoea in cattle, pigs and sheep.a total of 1572 isolates of escherichia coli obtained from the faeces of young farm animals with diarrhoea over the period 1980-1983 were screened for resistance to trimethoprim (tp). resistance to tp was detected in 263/954 (28%) of bovine isolates, 59/441 (13%) of porcine isolates and 15/177 (9%) of ovine isolates. seventy-five resistant isolates from separate outbreaks of infection on farms within a 25 mile radius of nottingham were examined in detail. sixty-eight (91%) of the 75 isolates wer ...19853897163
mini-mulac transposons with broad-host-range origins of conjugal transfer and replication designed for gene regulation studies in rhizobiaceae.novel mini-mu derivatives were constructed, carrying a truncated laczya operon fused to the terminal 117 bp of the mu s-end, for the isolation of translational lac fusions by mini-mu-mediated insertion mutagenesis. different selectable markers (chloramphenicol resistance; gentamycin resistance) were introduced to allow selection for mini-mu insertions in different replicons and bacterial strains. a mini-mulac derivative carrying the site for conjugal transfer of plasmid rp4 (orit) and the origin ...19882838383
transfer of plasmid rp4 to myxococcus xanthus and evidence for its integration into the chromosome.the broad-host-range plasmid rp4 and its derivative r68.45 were transferred to myxococcus xanthus dk101 and dz1; rp4 was maintained integrated in the chromosome. loss of plasmid markers occurred during the growth of the transconjugants, which could be prevented by selective pressure with oxytetracycline. the integrated plasmid was transferred back to escherichia coli often as rp4-prime plasmids carrying various segments of the m. xanthus chromosome. it also mediated chromosomal transfer between ...19853918015
[compatibility of transposable phages of escherichia coli and pseudomonas aeruginosa. i. co-development of phages mu and d3112 and integration of phage d3112 into rp4::mu plasmid in pseudomonas aeruginosa cells].the possibility of using a model system (which included rp4::mu plasmid and d3112 phage in pseudomonas aeruginosa cells) for analysis of compatibility of transposable escherichia coli phage mu and p. aeruginosa phage d3112, as phages and transposons, was studied. no interaction was observed during the vegetative growth of phages. the majority of the hybrid rp4::mu plasmids lost the mu dna after insertion of d3112 into rp4::mu. the phenomenon was not a result of transposition immunity. we conside ...19882840341
[oxidation of n-alkanes by pseudomonas aeruginosa strain carrying the plasmid pbs251].pseudomonas aeruginosa pao8 cannot use n-alkanes or their respective alcohols as a sole carbon source. however, it can grow on n-alkanes when plasmid pbs251 is transferred into its cells. the hybrid plasmid pbs251 is a plasmid rp4 containing genes which control the capability to grow on n-alkanes of the c6-c12 series. studies of n-alkane oxidation by p. aeruginosa pao8 carrying pbs251 have shown that this plasmid controls the inducible alkane and alcohol oxidizing activities; the subsequent step ...19853937960
genetic and biophysical study of r plasmids conferring sulfonamide resistance in shigella strains isolated in 1952 and 1956.the conjugative plasmids determining sulfonamide resistance in five shigella strains, each isolated from a different patient, have been characterized. one s. flexneri 2a strain, isolated in 1952, harbored an fi(+) plasmid of molecular weight 53 x 10(6), which specified synthesis of f-like pili and bore determinants for sulfonamide resistance (su) and bacteriocinogeny (col). this plasmid was compatible with plasmids of groups f(i), f(ii), i(alpha), and p. a second s. flexneri 2a strain isolated i ...19744215794
lincomycin stimulates synthesis of tem-2 beta-lactamase by escherichia coli.lincomycin increased the tem-2 beta-lactamase activity of escherichia coli k-12 cells carrying plasmid rp4 at a concentration which slightly inhibited cell growth. in a control culture beta-lactamase activity reached its maximal level in late log phase, whereas when lincomycin was present beta-lactamase activity continued to increase into the stationary phase. lincomycin (100 micrograms/ml) inhibited both cell growth and protein synthesis by about 35% but stimulated beta-lactamase activity 2.5-f ...19863530127
survival of and plasmid stability in pseudomonas and klebsiella spp. introduced into agricultural drainage water.cell survival and plasmid stability in pseudomonas fluorescens r2f and pseudomonas putida cym 318 containing respectively, plasmid rp4 and prk2501, and klebsiella aerogenes nctc 418 harboring plasmid pbr322 were studied in sterile and nonsterile agricultural drainage water under both aerobic and anaerobic conditions and in the absence and presence of added nutrients. both pseudomonas strains survived well in sterile drainage water incubated aerobically, with or without added nutrients. however, ...19892590305
[molecular cloning and functional analysis of dna regions of plasmid rp4 determining the incompatibility properties].sau3a-generated dna fragments determining incompatibility functions of the plasmid rp4 were cloned on the vectors ptk16 and pbr322. inc+ recombinant plasmids were divided into two types: 1) expressing incompatibility only towards the homologous rp4 replicon, 2) expressing incompatibility - both towards the homologous rp4 replicon and towards the heterologous replicons of plasmids r906 and r751. for one member of the first type plasmids it was shown that the cloned inc+-specific insertion derived ...19863021575
[expression of pseudomonas aeruginosa phage transposons in pseudomonas putida ppg1 cells. ii. zygotic induction--a necessary condition for the formation of defective lysogens].the transfer of hybrid plasmid rp4::pt (where pt is the genome of a transposable phage specific for pseudomonas aeruginosa) into recipient cells of p. putida strain ppg1 occurs with the same frequency as into p. aeruginosa, the homologous host for pt. approximately 1/3 of all ppg1 exconjugants carrying rp4 markers lost the capability to produce viable pt phage. in contrast, in a cross with homologous recipient p. aeruginosa all exconjugant clones contained nondefective prophages in the hybrid pl ...19853002910
[effective, plasmid rp4-dependent replication-transposition of dna of the transposable phage d3112 of pseudomonas aeruginosa in a heterologous escherichia coli system].the processes of replication and transposition of pseudomonas aeruginosa transposable phage d3112 in cells of escherichia coli (d3112) and e. coli (rp4::d3112) were studied. d3112 genome is a "silent cassette" ("conex-phage"--conditionally expressible) in e. coli cells incubated at 42 degrees c. two compulsory conditions for d3112 genome expression are incubation at 30 degrees c and the presence in cells of rp4 plasmid. processes of replication and transposition in e. coli are coupled. rp4 plasm ...19863021578
construction of transposons carrying the transfer functions of rp4.the transfer genes and origin of transfer of the wide host range plasmid rp4 have been cloned into the transposons tn1 and tn5. the newly constructed transposons can be used to mutagenize bacterial plasmids or the chromosome in species such as escherichia coli or rhizobium. it is then possible to mobilize the plasmid or chromosome using the transfer functions provided in cis by the transposon. these constructs may aid chromosome mapping in many gram-negative species by allowing the wider use of ...19882854282
f factor inhibition of conjugal transfer of broad-host-range plasmid rp4: requirement for the protein product of pif operon regulatory gene pifc.by the use of deletions, point mutations, and gene fusions, we show that the protein product of the f factor pifc gene is responsible for f factor inhibition of plasmid rp4 conjugal transfer. deletion analysis of pif sequences carried by psc101-f chimeric plasmids demonstrated that removal of all or part of the pifc coding sequence greatly decreased or abolished the ability of these plasmids to inhibit rp4 transfer. amber mutations in the pifc gene eliminated inhibition in an su- host strain but ...19852993231
[characteristics of derivatives of the plasmid rp4 in a broad range of hosts with altered properties of maintenance and inheritance].hydroxylamine-induced mutants of the plasmid ppd6 (8.4 kb) were isolated which are resistant to high doses of tetracycline. one of the plasmids studied--ppd21 is a multicopy mutant, another one, ppd12 is a dimeric form of the ppd6 plasmid. the ppd12 plasmid is very unstable, its derivative, ppd13 spontaneous mutant acquiring stability but not the ability to resolve dna multimeric forms into monomeric forms. multicopy bireplicon ppd619 plasmid was constructed by joining in vitro ppd6 and puc19 pl ...19863026896
adenine + thymine content of different genes located on the broad host range plasmid rp4.the genetic map of plasmid rp4 was correlated with its adenine+thymine (at) map. for this purpose, rp4 dna was digested with one or both of the restriction enzymes ecori and hindiii and the resulting linear rp4 molecules and fragments were partially denatured, examined in the electron microscope and their at maps were determined using a computer program. from these at maps the ecori and hindiii restriction sites were located on the at map of rp4. since the positions of these restriction sites on ...19806248619
transfer of the ti plasmid from agrobacterium tumefaciens into escherichia coli cells.we have screened strains of agrobacterium tumefaciens for spontaneous mutants showing constitutive transfer of the nopaline ti plasmid ptic58 during conjugation. the ti plasmid derivatives obtained could be transferred not only to a. tumefaciens but also to e. coli cells. the ti plasmid cannot survive as a freely replicating plasmid in e. coli, but it can occasionally integrate into the e. coli chromosome. however, insertion in tandem of plasmids carrying fd replication origins (pfd plasmids) in ...19883049936
[restriction and electron microscopic analyses of deletion derivatives thermosensitive with respect to maintaining plasmid peg1].temperature-independent deletion mutants of temperature-sensitive in self-maintenance plasmid peg-1, derived from r-factor rp4, are mapped using the restriction endonucleases psti, smai, ecori, bamhi and the heteroduplex analysis. the peg1 derivatives under study are found to have deletions in the area of ampicillin transposon tn1 and nearby genes. the left and the right ends of these deletions boundaries are localized between 37.5 md and 7.6 md in the rp4 map. thus far, the area of plasmid rp4 ...19806257589
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