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1.
Thirty mutants sensitive to tetracycline were obtained from an R100 factor capable of conferring resistance to tetracycline (TC), chloramphenicol (CM), streptomycin (SM) and sulfanilamide (SA). Among the TC sensitive mutants, three showed a high frequency of spontaneous loss from host strains. The genetic loci governing the stability of R factor in host bacteria were denoted as stb. The stb– R factors have lost many of the properties of a wild type R factor, such as, the capability to sexually transfer drug resistance and host chromosome, to confer superinfection immunity and to inhibit F function. All of these properties did not revert to a wild type phenotype, suggesting that these mutations are deletions including genetic determinants governing both TC resistance and stability of R factor. Recombinational analysis between stb– and stb+ R factors indicated that crossovers between the stb loci and those governing CM (or SM.SA) resistance took place at high frequency. No crossovers were detected between stb loci and those governing TC resistance, indicating that the stb loci are linked closely to the loci governing TC resistance. 相似文献
2.
Kenji Harada Mitsuo Kameda Mitsue Suzuki Susumu Shigehara Susumu Mitsuhashi 《Journal of bacteriology》1967,93(4):1236-1241
The R21(TC) factor, obtained by transduction of the R10(TC.CM.SM.SA) factor with phage ε to group E Salmonella, is not transferable by the normal conjugal process. However, when R21(TC)+ transductants are infected with the F13 factor, the nontransferable R21(TC) factor acquires transmissibility by conjugation. R21(TC)+ conjugants of Escherichia coli K-12, to which only the R21(TC) factor was transmitted by cell-to-cell contact from an F′ R+ donor, were still unable to transfer their R21(TC) factor by conjugation. In crosses between Hfr and F−E. coli K-12 strains containing R21(TC), the gene responsible for tetracycline resistance was located on the E. coli K-12 chromosome between lac and pro, near lac. 相似文献
3.
Sequence Analysis of the Florfenicol Resistance Gene Encoded in the Transferable R-Plasmid of a Fish Pathogen,Pasteurella piscicida 总被引:2,自引:0,他引:2
The florfenicol resistance gene (pp-flo) derived from a transferable R-plasmid of Pasteurella piscicida consisted of 1,122 nucleotides, and the predicted amino acid sequence showed 47.4% identity to that of a non-enzymatic chloramphenicol resistance gene (cmlA). The pp-flo gene was located in the downstream region of the sulfonamide resistance gene of the transferable R-plasmid. 相似文献
4.
In conjugation experiments betweenEnterobacter cloacae DF13 andEscherichia coli K12, resistances against tetracycline, sulfanilamide, streptomycin, and chloramphenicol were nearly always transferred simultaneously.
These properties could be transferred fromE. coli exconjugants by transduction to a drug-sensitiveE. coli K12 strain with bacteriophage P1kc. It may be inferred thatEnt. cloacae DF 13 harbours a multiple R factor, which promotes its own transfer. This R factor was found to be of thefi
+ type. The molecular nature of this R factor was studied by labelling the DNA of an exconjugant with3H-thymidine, careful lysis, sedimentation of the chromosomal DNA, and characterization of the circular DNA by sucrose-gradient
centrifugation, equilibriumdensity centrifugation in CsCl containing ethidium bromide and by electron microscopy. By these
methods the multiple R factor was identified as a circular DNA molecule with a contour length of 22.6 Μm, corresponding to
a molecular weight of 45 × 106 daltons. A segregant R factor harbouring resistance against tetracycline only, was found to have a contour length of 16.0
Μm and a sedimentation constant of 58 S. In addition to the multiple R factor, the wild-type strain harboured a plasmid with
a sedimentation constant of 38 S, corresponding to a molecular weight of 16 × 106 daltons. The function of this plasmid is unknown. After many transfers on agar slants spontaneous segregation of the R factor
was observed and several types of segregants were obtained. In most segregants, resistance against streptomycin could not
be transferred by conjugation and could not be mobilized by other sex factors. Some of these segregants had acquired a requirement
for methionine; in these, the streptomycin-resistance determinant may be integrated into the chromosome. The resistance pattern
of the various types of segregants and exconjugants allowed to draw a circular map of the R factor. The order of markers is
---tet---rtf---sul---str---cml-.
After short-term conjugation experiments most exconjugants were found to have received resistance against sulfanilamides only.
This resistance determinant does not promote its own transfer by conjugation but could be mobilized by other sex factors.
An exconjugant become resistant against tetracycline and sulfanilamide, was found to harbour two independent plasmids of which
only that carrying resistance against tetracycline promoted its own transfer. Consequently a second R factor, determining
resistance against sulfanilamide alone must be present inEnt. cloacae DF13. This R factor was identified as a circular DNA molecule with a sedimentation constant of 26 S, a contour length of
2.6 Μm and a buoyant density of 1.709.
From a strain harbouring the independent R(SA) plasmid and an R(TC) fragment of the multiple R factor, transductants resistant
against sulfanilamide were obtained. These were found to harbour an R(SA) plasmid with properties of a defective Rfi
+ transfer factor. Most probably these plasmids resulted from recombination between the R(SA) plasmid and the Rtf region of
the R(TC) fragment.
The author published previously under the name of “G. A. Tieze”.
The technical assistance of Miss J.T.M.P.A. Havermans, Mrs. A. Mak-Zuidervaart, and Mr. M. V. M. Lafleur is gratefully acknowledged.
The authors thank Dr. E. F. J. van Bruggen and Dr. D. Ellens for the electronmicroscopical measurements. 相似文献
5.
Kenji Harada Mitsuo Kameda Mitsue Suzuki Susumu Mitsuhashi 《Microbiology and immunology》1967,11(2):143-151
A nontransferable R21 (TC) factor was obtained by transduction of R10 (TC.CM.SM.SA) with phage epsilon in group E Salmonella. The R21 (TC) factor acquired transmissibility by the normal conjugal process when group E Salmonella strains harboring R21 (TC) factor were infected with wild-type F or R16 (CM) factor. This transmissibility at high frequency was accounted for by the formation of the recombinant F TC and R10 (CM) TC factors. The F TC and R16 (CM) TC factors were genetically the same as the original F and R16 (CM) factors, except for the ability to confer TC resistance. In the transduction of F TC factor with phage P1, a dF TC (d: defective) factor was obtained that was defective in many F properties, such as the ability to introduce host chromosome and produce male substance, but was capable of transducing TC resistance (dF TC-infection) at low frequency. 相似文献
6.
Tokumitsu Tanaka Hajime Hashimoto Yutaka Nagai Susumu Mitsuhashi 《Microbiology and immunology》1967,11(3):155-162
Drug resistance of 3,000 Shigella strains isolated in 1965 were investigated. These strains originated from 10 City Hospitals and 4 Prefectural Health Centers, which are located in different parts of Japan. One hundred and seventy strains which were resistant to 4 drugs, chloramphenicol (CM), tetracycline (TC), dihydrostreptomycin (SM), and sulfanilamide (SA), were selected at random from these stock cultures in this laboratory and the distribution of R factors in these isolates was examined. It was found that the strains all harbored R factors which were capable of transferring drug resistance by usual conjugal process. Among the strains carrying R factors, 85 per cent harbored a single type of R factor and 15 per cent carried two types of R factor in a cell. The latter is called the hetero-R state. Among the strains in the hetero-R state, isolation of strains harboring both R (SM.SA) and R (TC.CM.SM.SA) factors was most frequent. It was found that 25 R (SM.SA) factors isolated from strains in hetero-R had the genetic determinant iR?, while most of the R (TC.CM.SM.SA) factors isolated from natural sources were iR+. When two types of R factor, R (SM.SA) and R (TC.CM.SM.SA) derived from the same host cells, were brought together in a host cell by superinfection with both factors, they were found to exist stably in a host bacterium. These results confirmed the stable existence of both factors in Shigella strains isolated from dysenteric patients. 相似文献
7.
We report here novel array of gene cassettes found in single variable region of class 1 integron disseminated in Pseudomonas aeruginosa isolated from a teaching hospital in Nanjing, Jiangsu Province, China. 29 of 47 (61%) P. aeruginosa strains were confirmed haboured class 1 integron, and all the positive strains have the same variable region confirmed by
PCR and RFLP methods. The variable region contained an unreported order of four gene cassettes aac(6′)-II-aadA13-cmlA8-oxa-10. Of those, cmlA8 gene was a variant of cmlA5 encoding non-enzymatic protein which putatively confer resistance to chloramphenicol. Susceptibility testing revealed multidrug-resistant
mechanisms were involved in the class 1 integron positive clinical isolates. And the class 1 integron located on an about
15 kb transferable plasmid was certified by conjugation experiment and plasmid DNA analysis. The macro restriction profile
indicated those clinical strains were clonally related.
These authors contributed equally to this work. 相似文献
8.
Takashi Aoki Tadatoshi Kitao Satoshi Watanabe Sunao Takeshita 《Microbiology and immunology》1984,28(1):1-9
Two hundred twenty-six strains of Vibrio anguillarum collected from cultured ayu (Plecoglossus altivelis) between 1978 and 1980 were studied for their sensitivities to 10 chemotherapeutics. In order to determine whether the drug-resistant strains possessed transferable R plasmids, they were conjugated with Escherichia coli. Almost all the strains isolated during the 3 years showed resistance to nalidixic acid (NA) and/or furazolidone (NF). NA and NF resistance were not transferred to Escherichia coli from any of the strains. Chloramphenicol-resistant strains were isolated in every year and almost all of them carried transferable R plasmids. Only one strain with tetracycline resistance was found among the strains tested. Strains resistant to sulfonamides, streptomycin, ampicillin (ABP), and trimethoprim (TMP) increased rapidly in 1980, and a large number of them carried transferable R plasmids. Transferable R plasmids encoded with resistance to ABP and TMP were detected for the first time in V. anguillarum strains. The R plasmids detected in the strains isolated in 1980 were classified into incompatibility groups E, A, and an untypable group. The R plasmid DNAs were cleaved by EcoRI to yield 11 to 13 fragments. The estimated molecular weights of the R plasmids from the five strains ranged from 97 to 104 M daltons. 相似文献
9.
Megumi Kono Koji O'Hara Masatoshi Nagawa Susumu Mitsuhashi 《Microbiology and immunology》1971,15(3):219-227
Induction of chloramphenicol (CM) resistance in Staphylococcus aureus was investigated using 166 CM derivatives and analogues. It was found that 18 compounds of the samples used were able to induce resistance to CM in Staphylococcus aureus S1477 harboring an inducible CM-resistance determinant. Most of the samples which had a nitrophenyl moiety and a D- or DL-threo isomer in its steric configuration were found to have inducer activity for CM resistance. Competent inducers are D-isomer CM derivatives which have another substituent in place of the hydroxyl group at carbon atom 3 in the propanediol of the drug. 相似文献
10.
Streptomycin-sensitivity in Streptomyces glaucescens is due to deletions comprising the structural gene coding for a specific phosphotransferase 总被引:12,自引:0,他引:12
Gilberto Hintermann Reto Crameri Martin Vögtli Ralf Hütter 《Molecular & general genetics : MGG》1984,196(3):513-520
Summary The wild type strain of Streptomyces glaucescens produces hydroxystreptomycin and has a natural resistance towards the streptomycin group aminoglycoside antibiotics. The inherent resistance is a genetically unstable character and mutant strains sensitive to streptomycins arise spontaneously at unusually high frequencies. The gene conferring streptomycin resistance was cloned and characterised as a streptomycin specific phosphotransferase. Hybridisation experiments show that the mutational event leading to sensitivity is due to large deletions, most likely on the chromosome, comprehending the structural gene coding for a streptomycin phosphotransferase and its flanking regions. Interspecific expression of the S. glaucescens phosphotransferase was found in Streptomyces lividans as well as in Escherichia coli.Abbreviations bp
base pairs
- EDTA
ethylenediaminetetraacetic acid
- kb
kilobases'
- TES
n-tris(hydroxymethyl) methyl-2-aminoethane sulfonic acid 相似文献
11.
Isolation and characterisation of a strain carrying a conditional lethal mutation in the cou gene of Escherichia coli K12. 总被引:34,自引:0,他引:34
Elisha Orr Neil F. Fairweather I. Barry Holland Robert H. Pritchard 《Molecular & general genetics : MGG》1979,177(1):103-112
Summary A strain which carries a mutation conferring clorobiocin resistance and temperature sensitivity for growth was isolated from Escherichia coli K12. Genetic mapping and the molecular weight of the gene product suggest that the mutation is in the cou gene, specifying a sub-unit of DNA gyrase. Nuclear organisation and segregation and placement of septa are grossly abnormal in the mutant at 42°C. RNA synthesis and initiation of DNA replication are also affected at the restrictive temperature but the rate of DNA chain elongation continues almost undisturbed. 相似文献
12.
Hitoshi Sagai V. Krcmery Katsumi Hasuda Shizuko Iyobe H. Knothe Susumu Mitsuhashi 《Microbiology and immunology》1975,19(6):427-432
Conjugal transferability of drug resistance was examined, in eleven Pseudomonas aeruginosa strains which were isolated in Frankfurt. Four R factors were demonstrated from three strains using P. aeruginosa as recipients but they were nontransferable to Escherichia coli K12. Two R factors, i.e., Rms146 and Rms147, mediated resistances to tetracycline (TC), streptomycin (SM), sulfanilamide (SA), kanamycin (KM), lividomycin (LV), gentamicin C complex (GM) and 3′,4′-dideoxykanamycin B (DKB). They mediated the formation of aminoglycoside-inactivating enzymes, i.e., SM phosphotransferase, SM adenylyltransferase, KM and LV phosphotransferase 1, and GM and DKB 6′-N-acetyltransferase. TC resistance conferred by these R factors was due to impermeability of the drug. P. aeruginosa Ps 142 carried two kinds of R factor in one cell, Rms148 (SM) and Rms149 (SM·SA·GM·CPC) (CPC, carbenicillin). Rms148 (SM) was transferable at a high frequency of 10–1 and mediated the formation of SM phosphotransferase. Rms149 mediated the formation of drug-inactivating enzymes, i.e., GM 3-N-acetyltransferase and β-lactamase, but did not inactivate SM. SM resistance was probably due to impermeability of the drug. 相似文献
13.
An MIC test of 12 chemotherapeutic agents performed on 175 strains of Pasteurella piscicida collected from cultured yellowtail (Seriola quinqueradiata) in different areas of Japan from 1989 to 1991 revealed 152 strains (87%) with resistance to combinations of ampicillin (AP), chloramphenicol (CP), kanamycin (KM), nalidixic acid (NA), sulfamonomethoxine (SA), tetracycline (TC), and/or trimethoprim (TMP). The remaining 23 strains were sensitive to all the drugs tested: AP, cefazolin, CP, florfenicol (FF), furazolidone, KM, NA, novobiocin, SA, streptomycin, TC, and TMP. FF showed the most effective antibacterial activity against P. piscicida with MICs ranging from 0.004 to 0.6 μg/ml. One hundred and forty-nine of the 152 resistant strains carried transferable R plasmids encoding one of the Cp Km Sa Tc, Km Sa Tc, Km Sa, and Sa resistance. The most common resistance marker of transferable R plasmids identified in P. piscicida was Km Sa Tc. R plasmids encoding three different resistant markers were very similar on the basis of their digestion patterns with restriction endonucleases. There was homology among the DNAs of nine transferable R plasmids selected. Our findings suggest that multiple drug resistant strains of P. piscicida carrying transferable R plasmids with the same DNA structure are common in yellowtail farms and that the R plasmid has been retained within the P. piscicida population without change in their DNA structure according to geography and year. 相似文献
14.
R. J. Leer H. Christiaens W. Verstraete L. Peters M. Posno P. H. Pouwels 《Molecular & general genetics : MGG》1993,239(1-2):269-272
A chloramphenicol-resistance gene (cml) was introduced into the Lactobacillus plantarum gene encoding conjugated bile acid hydrolasc (cbh) on a ColEl replicon. This plasmid which is nonreplicative in Lactobacillus was used to transform L. plantarum strain 80. A homologous double cross-over recombination event resulted in replacement of the chromosomal cbh gene by the cml-containing cbh gene. The transformants obtained were unable to synthesize active conjugated bile acid hydrolase (Cbh). The Cbh-CmlR phenotype was stably maintained for more than 100 generations under nonselective conditions.This paper is dedicated with great appreciation to Dr. Frits Berends on the occasion of his retirement as Head of the Biochemistry Department of the TNO Medical Biological Laboratory 相似文献
15.
Recently, an Escherichia coli CM2555 strain was described as sensitive to chloramphenicol when expressing the chloramphenicol resistance gene (cat) from a multicopy plasmid. This sensitivity was linked to dysfunction of the acrA gene, which encodes a component of the AcrAB-TolC multidrug efflux pump. Preliminary data indicate that the sensitivity phenotype might be due to a decline in intracellular acetyl coenzyme A concentration accompanying the reaction catalyzed by chloramphenicol acetyltransferase, the cat-encoded resistance protein. Here, we demonstrate that the acrA dysfunction is the factor impairing the intracellular acetyl coenzyme A levels in the cat-expressing CM2555 strain. This effect might be alleviated by the interplay of proteins constituting two homologous efflux systems: AcrAB-TolC and AcrEF-TolC. However, our results show also that this is a genetic background-specific phenomenon, as the decrease in acetyl coenzyme A level is not evident in a cat-bearing acrAB derivative of the commonly used strain C600. 相似文献
16.
L. G. van Waasbergen S. P. Kidambi R. V. Miller 《Applied microbiology and biotechnology》1998,49(1):59-65
A recA mutant was constructed of a soil isolate of Burkholderia cepacia, strain ATCC 17616. Prior to mutagenesis, the recA gene was cloned from this strain by its ability to complement the methyl methanesulfonate sensitivity of an Escherichia coli recA mutant. Sequence analysis of the strain showed high sequence similarity (94% nucleic acid and 99% amino acid identity) with
the recA gene previously cloned from a clinical isolate of B. cepacia, strain JN25. The subcloned recA gene from B. cepacia ATCC 17616 restored UV resistance and recombination proficiency to recA mutants of E. coli and Pseudomonas aeruginosa, as well as restoring the ability of D3 prophages to be induced to lytic growth from a RecA− strain of P. aeruginosa. The recA mutant of B. cepacia ATCC 17616 was constructed by λ-mediated Tn5 mutagenesis of the cloned recA gene in E. coli, followed by replacement of the Tn5-interrupted gene for the wild-type allele in the chromosome of B. cepacia by marker exchange. The RecA− phenotype of the mutant was demonstrated by the loss of UV resistance as compared to the parental strain. Southern hybridization
analysis of chromosomal DNA from the mutant indicated the presence of Tn5 in the recA gene, and the location of the Tn5 insertion in the recA allele was identified by nucleotide sequence analysis. A test using the recA mutant to see if acquired resistance to d-serine toxicity in B. cepacia might be a result of RecA-mediated activities proved negative; nevertheless, RecA activity potentially contributes to the
overall genomic plasticity of B. cepacia and a recA mutant will be useful in bioengineering of this species.
Received: 24 January / Received revision: 11 July 1997 / Accepted: 25 August 1997 相似文献
17.
Modification of lipid A structure and activity by the introduction of palmitoyltransferase gene to the acyltransferase‐knockout mutant of Escherichia coli
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Takehiro Sugawara Sakura Onoue Hiroaki Takimoto Kazuyoshi Kawahara 《Microbiology and immunology》2018,62(8):497-506
18.
Summary DNA fragments of the R factor R388 which renders E. coli resistant to trimethoprim by inducing a trimethoprim resistant dihydrofolate reductase (Amyes and Smith, 1974) were inserted into plasmids and screened for the expression of the trimethoprim resistance gene. By means of a two step deletion procedure a 1770 bp EcoRI/BamH1 fragment was isolated which conferred drug resistance and which was found to induce the synthesis of the same dihydrofolate reductase as the parental R factor. Gene dosage experiments indicated that the induction was due to the presence of a dihydrofolate reductase structural gene on the 1770 bp fragment. The gene could be assigned to a segment which was less than 1200 bp long. The 1770 bp fragment and a recombinant plasmid consisting of pSF2124 and part of R388 were mapped with several restriction nucleases. The R factor induced enzyme was partially purified from a strain carrying a multicopy recombinant plasmid into which the 1770 bp fragment was inserted and which induced high levels of dihydrofolate reductase. The enzyme was found to be stable at 100°. Some aspects of the synthesis of dihydrofolate reductase are discussed.Dedicated to Professor Peter Karlson on the occasion of his 60th birthday 相似文献
19.
Giuseppe Sermonti Luisa Lanfaloni Maria Rita Micheli 《Molecular & general genetics : MGG》1980,177(3):453-458
Summary The difficulty in mapping the gene for chloramphenicol resistance (cml
R) in Streptomyces coelicolor A3(2) stock strains is possibly due to its location on different sites of the chromosome in various mixed subelones. Fresh isolates from CmlR strains show single unequivocal locations of cml
R. The same holds for CmlR strains derived as revertants from CmlS variants. The two best established sites for cml
R are one between cys A and met A, the other at right of arg A, possibly in the right empty arc of the map (Fig. 2). The cml
R gene was assumed to be on a transposon (SCTn1), together with a gene for arginine-succinate synthase (argG), a gene for chromosome transfer (tra) and a gene for aereal mycelium formation (amy). In a CmlR revertant, the cml
R gene appears disjoined from argG (Fig. 5), thus showing the ability of SCTnl to be split and partially transposed. The possible wide occurrence of transposons in the genus Streptomyces is discussed. 相似文献
20.
An Escherichia coli mutant thermosensitive in the B subunit of DNA gyrase: effect on the structure and replication of the colicin E1 plasmid in vitro 总被引:13,自引:0,他引:13
Summary An E. coli strain which carries a mutation conferring clorobiocin resistance and temperature sensitivity for growth has recently been described and evidence has been presented suggesting that the mutation is located in the gyrB gene (Orr et al. 1979). The replication of the ColE1 plasmid was analysed in cell-free extracts from this thermosensitive strain. These extracts were totally deficient in the replication of exogenous plasmid DNA and were unable to maintain the superhelical structure of the plasmid DNA. Both defects could be fully complemented by addition of purified gyrB protein. 相似文献