| induction of protein x in escherichia coli. | certain treatments that damage dna and/or inhibit replication in e. coli have been reported to induce synthesis of a new protein, termed protein x, in reca+ lexa+ strains. we have examined some of the treatments that might induce protein x and we have, in particular, tested the hypothesis of gudas and pardee (1975) that dna degradation products play an essential role in the induction process. we confirmed that uv irradiation, nalidixic acid treatment, or thymine starvation result in protein x sy ... | 1977 | 321932 |
| the effect of a drug-resistance factor on recombination and repair of dna in escherichia coli k12. | the presence in recipient strains of escherichia coli k12 of the plasmid r46 greatly reduced the yield of recombinants from crosses with several hfr strains and virtually abolished the formation of recombinants by pi transduction without, however, significantly affecting the transfer of the f prime from a strain carrying fgal. the r46 plasmid had paradoxical effects on mutability: it appeared to enhance the yield of mutants following irradiation with ultraviolet ligh but it reduced the number of ... | 1977 | 330823 |
| segregation of the mutator property of plasmid r46 from its ultraviolet-protecting property. | plasmid r46 (an r factor conferring resistance to ampicillin, sulfonamides, streptomycin and tetracycline) reduces the bactericidal effect of uv irradiation but increases its mutagenic effect (reversion of hisg46), and raises the frequency of spontaneous reversion (mutator effect). putative deletion mutants of r46 were obtained by transduction of the plasmid, then two successive conjugal transfers. plasmids of five of six deletion classes, each with a different combination of drug resistance tra ... | 1979 | 368596 |
| effect of host lex, reca, recf, and uvrd genotypes on the ultraviolet light-protecting and related properties of plasmid r46 in escherichia coli. | the ability of plasmid r46 to reduce the lethal but enhance the mutagenic effect of ultraviolet (uv) irradiation was tested in sets of escherichia coli k-12 derivatives, wild type or with different mutations affecting dna repair capacity, but otherwise isogenic. uv protection and enhancement of uv mutagenic effect were obtained in uvra6, uvrb5, uvrd3, and recf143 hosts, but not in a reca56 strain. the plasmid gave some uv protection in two lexa1 and two lexa101 strains and in one lexa102 host, b ... | 1979 | 370103 |
| dna repair in proteus mirabilis. vi. plasmid (r46-) mediated recovery and uv mutagenesis. | the expression of plasmid r46-mediated recovery and mutagenic function (s) was studied in p. mirabilis, which is normally either weakly or non-mutable after uv exposure. the plasmid was found to confer on p. mirabilis enhanced uv resistance as well as uv-induced mutability for various types of forward mutations and reversion of the thr273 mutation. the plasmid enhanced survival of uv-irradiated phages in p. mirabilis both in unirradiated host cells and with increased efficiency after uv-exposure ... | 1979 | 393956 |
| ultraviolet light protection, enhancement of ultraviolet light mutagenesis, and mutator effect of plasmid r46 in salmonella typhimurium. | plasmid r46 partially protected salmonella typhimurium, wild type or uvrb or pola, against the lethal effect of ultraviolet (uv) irradiation, but did not protect reca mutants. the plasmid also increased frequency of uv-induced reversion to his+ in all tested his point mutants (wild type for uv sensitivity), including amber, ochre, uga, missense, and frame-shift mutants. plasmid r46 also increased uv-induced reversion to his+ in uvrb and pola strains, but no uv mutagenic effect was detected in r- ... | 1976 | 789333 |
| photobiological activity of certain new methylazapsoralens. | the photobiological activity of a series of psoralen isosters carrying a nitrogen atom at 8 position, new potential drugs for the photochemotherapy of hyperproliferative skin diseases, have been studied; the more active derivatives appeared to be 5,4'-dimethyl-8-azapsoralen and 3,4,4'-trimethyl-8-azapsoralen which induced a strong inhibition of dna synthesis in ehrlich ascites cells, very similar to that provoked by 8-methoxypsoralen, the furocoumarin at present used in photochemotherapy. such c ... | 1992 | 1294168 |
| the integron in1 in plasmid r46 includes two copies of the oxa2 gene cassette. | the sequence of the insert region of the integron in1 found in the incn plasmid r46 was completed. the insert region is 2929 bases long and includes four gene cassettes, two of which are identical copies of the oxa2 gene cassette flanking an aada1 cassette. the fourth cassette encodes an open reading frame orfd. from comparison of these data with published maps and sequences it is argued that the integrons found in the incn plasmids pcu1 and r1767 and in the transposon tn2410 are closely related ... | 1992 | 1334268 |
| structural and functional analysis of the origin of conjugal transfer of the broad-host-range incw plasmid r388 and comparison with the related incn plasmid r46. | we cloned and sequenced a 402 bp dna segment containing the origin of conjugal transfer (orit) of the incw plasmid r388. progressive deletions from each end of the sequence were assayed for orit activity. stepwise reductions in mobilization frequencies, representing the loss of functional elements, correlated with deletion of structural motifs in the sequence. a sequence of 330 bp of orit was sufficient for efficient mobilization. the first 86 bp of the sequence contains five tandemly repeated d ... | 1991 | 2038309 |
| sulfonamide resistance gene for plant transformation. | the sulfonamide resistance gene from plasmid r46 encodes for a mutated dihydropteroate synthase insensitive to inhibition by sulfonamides. its coding sequence was fused to the pea ribulose bisphosphate carboxylase/oxygenase transit peptide sequence. incubation of isolated chloroplasts with the fusion protein synthesised in vitro, showed that the bacterial enzyme was transported to the chloroplast stroma and processed into a mature form. expression of the gene fusion in transgenic plants resulted ... | 1990 | 2103427 |
| expression of the sulfonamide resistance gene from plasmid r46. | the expression of the sul i gene from plasmid r46, a wide host range plasmid of the incn incompatibility group, was studied in escherichia coli. using a promoter test vector, a promoter was detected upstream of the sul i gene. from a nuclease protection experiment, the transcription was determined to start 360 bp upstream of the coding sequence. two putative promoter -35 and -10 sequences were found upstream from the predicted transcription start. the presence of this promoter sequence in other ... | 1990 | 2190244 |
| nucleotide sequence of the sulfonamide resistance gene from plasmid r46. | | 1989 | 2662140 |
| nucleotide sequence of an oxa-2 beta-lactamase gene from the r-plasmid r1767 derived plasmid pbp11 and comparison to closely related resistance determinants found in r46 and tn2603. | plasmid pbp11 contains a sequence homologous to tn21-like element tn2410 encoding dihydropteroate synthetase and beta-lactamase oxa-2. the nucleotide sequence of a 1.5 kb segment of this region has been determined including the bla gene. it reveals strong sequence homology with the oxa-2 operon of plasmid r46. the implications of an additional 319 bp segment in pbp11 for the different evolution of r46/pkm101 and pbp11 are discussed. | 1989 | 2689593 |
| the region of the incn plasmid r46 coding for resistance to beta-lactam antibiotics, streptomycin/spectinomycin and sulphonamides is closely related to antibiotic resistance segments found in incw plasmids and in tn21-like transposons. | the nucleotide sequence of a 2.5 kb segment of the pkm101 (r46) genome has been determined. the 1.3 kb from a bamhi site at 153 to base 1440 differs by only 2 bases from a part of the published sequence of the aadb (gentamicin resistance) gene region including the coding region for the n-terminal 70 amino acids of the predicted aadb product. the same sequence has been found 5'-to the dhfrii gene of r388 and to the aada gene of tn21 (r538-1). three open reading frames are located in this region, ... | 1987 | 2821509 |
| development of natural and synthetic dna probes for oxa-2 and tem-1 beta-lactamases. | cloning of a 6.3-kilobase bglii dna fragment from plasmid r46 permitted the isolation of the oxa-2 beta-lactamase gene. selected dna fragments internal and adjacent to the oxa-2 beta-lactamase structural gene were used as probes in homology studies with other plasmid-mediated beta-lactamases. under conditions of high stringency, no cross hybridization could be detected with dna probes from within the open reading frame of the oxa-2 structural gene. at a lower stringency, one of two dna fragments ... | 1987 | 3038006 |
| the origin of transfer (orit) of the conjugative plasmid r46: characterization by deletion analysis and dna sequencing. | the origin of transfer (orit) is the sequence within which conjugal transfer of plasmid dna is initiated, and is absolutely required in cis for plasmid mobilization. we have cloned orit from the 52 kb incn plasmid r46 on a 600 bp fragment, and mapped the limits of the relevant sequence by deletion analysis and transposon mutagenesis. the nucleotide sequence of the orit region contains 13 direct repeats of an 11 bp consensus sequence, 3 different pairs of 10 bp inverted repeats, and a segment tha ... | 1987 | 3039307 |
| mobilization of thiobacillus ferrooxidans plasmids among escherichia coli strains. | nonconjugative thiobacillus ferrooxidans plasmids were mobilized at high frequencies among escherichia coli strains by the incp plasmid rp4 and at low frequencies by the incn plasmid r46, but not by the incw plasmid psa. the mobilization region of a nonconjugative t. ferrooxidans plasmid was located on a 5.3-kilobase t. ferrooxidans dna fragment. | 1985 | 3890747 |
| mutagenesis-enhancement by plasmids in mutagenesis tester strains. | the plasmid pkm101 has played a very important role in the success of the ames salmonella test for carcinogens and mutagens. it was derived from the clinically isolated plasmid r46 by an in vivo deletion and confers upon its host both increased resistance to killing by uv irradiation and increased susceptibility to uv and chemical mutagenesis. pkm101 exerts its effects by coding for two genes muca and mucb, which are analogs of the chromosomally-encoded genes umud and umuc. the products of the u ... | 1985 | 3904713 |
| plasmid r46-mediated protection against bleomycin is pola+-dependent. | strains of escherichia coli deficient in post-replication recombination repair were more sensitive to bleomycin than wild-type, repair-proficient strains. mutants lacking excision repair functions were no more sensitive to bleomycin than the wild-type strains, indicating that this pathway is not involved in the repair of bleomycin-damaged dna. plasmid r46 not only protected repair-proficient strains but also those with recb, recc, uvra or lig genotypes, suggesting that r46 protection against ble ... | 1982 | 6176674 |
| a physical and genetic map of the incn plasmid r46. | | 1981 | 6264522 |
| restriction endonuclease cleavage map of pkm101: relationship to parental plasmid r46. | a detailed restriction endonuclease cleavage map of the plasmid pkm101 has been constructed. pkm101 plasmids containing individual tn5 insertions were used to facilitate the ordering of restriction fragments generated by enzymes cleaving pkm101 at multiple sites. by restriction enzyme analysis, pkm101 (35.4 kilobases) appears to have arisen from its clinically-isolated parent by deletion of a single dna region which codes for three of the four drug resistances carried by r46. | 1981 | 6270504 |
| r46-derived recombinant plasmids affecting dna repair and mutation in e. coli. | recombinant plasmids which render their host less mutable and more sensitive to some dna-damaging agents have been isolated from the n-group plasmid r46. these plasmids have been physically mapped and found to originate from the region of r46 that has been deleted in pkm101. this deleted region is well removed from the muc region of r46 and pkm101 which is responsible for the mutator effects of these plasmids. the effect of these anti-mutagenic plasmids on the ability of pkm101 to complement umu ... | 1982 | 6287166 |
| plasmid r46 provides a function that promotes reca-independent deletion, fusion and resolution of replicon. | we report that plasmid r46 provides a function which promotes reca-independent deletion, replicon fusion, and resolution of the fusion. r46 belongs to the incompatibility group n and specifies resistance to ampicillin, tetracycline, streptomycin and sulfonamide. four kinds of deletion derivatives were observed by selection for susceptability to tetracycline from ampicillin-resistant clones. a common region, will be called alpha region thereafter, was postulated to be involved in these deletions. ... | 1984 | 6319964 |
| plasmid r46 fails to protect escherichia coli against double-strand dna-binding agents but increases their mutagenic activities. | plasmid r46 was tested for its ability to increase survival and mutagenesis of escherichia coli strain ab1157 following exposure to agents that produce a variety of structural defects in dna. the plasmid enhanced the mutagenic activities of adriamycin (adm), n,n'-bis(2-chloroethyl)-n-nitrosourea (bcnu), bleomycin (blm), methyl methanesulphonate (mms), mitomycin c (mtc), nitrofurazone (nfz), 4-nitroquinoline-n-oxide (nqo), cis-platinum (ii) diaminodichloride (pdd) and proflavine (pf). furthermore ... | 1983 | 6338351 |
| r-plasmid effects on bacterial multiplication and survival. | the multiplication of escherichia coli c containing either the plasmid r46 or its non-selftransmissible derivative was studied in the presence or absence of the isogenic r- parent strain. neither plasmid conferred any detectable effect on the host's ability to multiply. similarly under conditions of prolonged incubation neither plasmid conferred a disadvantage on its host when the bacteria were grown in pure culture. however, when the incubation of mixed r+/r- cultures was prolonged, the possess ... | 1983 | 6351740 |
| comparison of the escherichia coli umu+-encoded function with plasmid r46-mediated error-prone repair in dna-damaged cells. | escherichia coli strain tk701 umu+ was more resistant than strain tk702 umu when tested against bleomycin (blm), cis-platinum(ii) diamminodichloride (pdd), ultraviolet light and methyl methanesulphonate (mms), which produce single-strand dna damage. however, the umu mutant was no more sensitive to mitomycin c (mtc) or proflavine (pf), which cause double-strand dna binding. strain tk702 umu was nonmutable by any of the agents, whereas mutations were induced in the wild-type strain by pdd, uv, mms ... | 1984 | 6366535 |
| plasmid-mediated uv-protection in myxococcus xanthus. | plasmid r46 was successfully transferred from escherichia coli k=12 into myxococcus xanthus strain md-1 but not into m. xanthus strain xk. plasmid r68.45 was transferred from e. coli k-12 into both strains of m. xanthus. the effects of these plasmids on survival of m. xanthus after ultraviolet (uv)-244 nm irradiation, the ability of m. xanthus to reactivate irradiated myxophages, and weigle reactivation of uv-irradiated effect on uv survival of m. xanthus, but increased the host's ability to rea ... | 1981 | 6790909 |
| repair and plasmid r46 mediated mutation requires inducible functions in proteus mirabilis. | in proteus mirabilis nalidixic acid or a predose of uv induce rec protein formation, a portion of post-uv replication repair and "post-uv replication enhancement." these inducible functions are not significantly affected by the plasmid r46, which renders p. mirabilis efficiently uv-mutable. the r46-mediated uv induction of rif mutations requires additional inducible functions, as existing after nalidixic acid treatment in rec+ strains. after a nalidixic acid pretreatment uv efficient induction o ... | 1981 | 7035831 |
| the arsenical resistance operon of incn plasmid r46. | the arsenical resistance operon of the incn plasmid r46 consists of 4696 bp and starts with predicted transcriptional control and initiation signals, followed by five genes, arsd, arsa, and arsc. the corresponding escherichia coli chromosomal ars operon and two staphylococcal ars operons lack arsa and arsd genes. the r46 system contains only the second known versions of arsa and arsd, after those of plasmid r773. western blot analysis identified the r46 proteins using antibodies against r773 ars ... | 1996 | 8674982 |
| expression and regulation of the arsenic resistance operon of acidiphilium multivorum aiu 301 plasmid pkw301 in escherichia coli. | the arsenic resistance (ars) operon from plasmid pkw301 of acidiphilium multivorum aiu 301 was cloned and sequenced. this dna sequence contains five genes in the following order: arsr, arsd, arsa, arsb, arsc. the predicted amino acid sequences of all of the gene products are homologous to the amino acid sequences of the ars gene products of escherichia coli plasmid r773 and incn plasmid r46. the ars operon cloned from a. multivorum conferred resistance to arsenate and arsenite on e. coli. expres ... | 1998 | 9464374 |
| [conserved upstream regulatory elements in the leader of transmission plasmid r46]. | | 1998 | 9720066 |
| plasmid-encoded mucb protein is a dna polymerase (pol ri) specialized for lesion bypass in the presence of muca', reca, and ssb. | replication through damaged sites in dna requires in escherichia coli the sos stress-inducible dna polymerase v (umuc), which is specialized for lesion bypass. homologs of the umuc gene were found on native conjugative plasmids, which often carry multiple antibiotic-resistant genes. mucb is a umuc homolog present on plasmid r46, and its variant plasmid pkm101 has been introduced into salmonella strains for use in the ames test for mutagens. using a translesion replication assay based on a gapped ... | 2000 | 11016960 |
| family of class 1 integrons related to in4 from tn1696. | the class 1 integron in28, found in the multidrug resistance transposon tn1403, was found to be located in the res site of the backbone transposon and is flanked by a 5-bp direct duplication, indicating that it reached this position by transposition. in28 has a backbone structure related to that of in4, but has lost internal sequences, including the sul1 gene, due to an is6100-mediated deletion. in28 also lacks the partial copy of is6100 found in in4 and contains different gene cassettes, blap1, ... | 2001 | 11600350 |
| assessment of the fitness impacts on escherichia coli of acquisition of antibiotic resistance genes encoded by different types of genetic element. | little is known of the fitness cost that antibiotic resistance exerts on wild-type bacteria, especially in their natural environments. we therefore examined the fitness costs that several antibiotic resistance elements imposed on a wild-type escherichia coli isolate, both in the laboratory and in a pig gut colonization model. | 2005 | 16040624 |
| [sos-induction in the presence of the plasmid pkm101 in the bacterial cells escherichia coli k12]. | induction of transcription by the plasmid pkm101 (mutability mediating derivate of the plasmid r46) of the sfia gene controlling cell division and of the frua gene encoding the fructose specific enzyme ii of the phosphoenolpyruvate-phosphotransferase system in intact cultures of escherichia coli was studied. the genes under study were fused to the bacteriophage mu dl (ap lac). activation of the sfia gene, a typical member of the sos-regulon, was demonstrated to depend on the key genes of the sos ... | 2006 | 16512604 |
| isolation of plasmid pkm101 in the stocker laboratory. | pkm101 is a mutagenesis-enhancing resistance transfer plasmid (r plasmid) that was introduced into several tester strains used in the salmonella/microsome mutation assay (ames test). plasmid pkm101 has contributed substantially to the effectiveness of the ames assay, which is used on a world-wide basis to detect mutagens and is required by many government regulatory agencies for approval to market new drugs and other chemical agents. widely used since 1975, the ames test is still regarded as one ... | 2006 | 16716644 |
| complete nucleotide sequence of pkp96, a 67 850 bp multiresistance plasmid encoding qnra1, aac(6')-ib-cr and blactx-m-24 from klebsiella pneumoniae. | the multiresistance plasmid pkp96 from klebsiella pneumoniae was sequenced completely and analysed concerning its genetic environment and distributing of antimicrobial resistance genes. | 2008 | 18812424 |