| bacteriophage p1 genes involved in the recognition and cleavage of the phage packaging site (pac). | the packaging of bacteriophage p1 dna is initiated by cleavage of the viral dna at a specific site, designated pac. the proteins necessary for that cleavage, and the genes that encode those proteins, are described in this report. by sequencing wild-type p1 dna and dna derived from various p1 amber mutants that are deficient in pac cleavage, two distinct genes, referred to as paca and pacb, were identified. these genes appear to be coordinately transcribed with an upstream p1 gene that encodes a ... | 1992 | 1538406 |
| phage lambda cdna cloning vectors for subtractive hybridization, fusion-protein synthesis and cre-loxp automatic plasmid subcloning. | we describe the construction and use of two classes of cdna cloning vectors. the first class comprises the lambda exlx(+) and lambda exlx(-) vectors that can be used for the expression in escherichia coli of proteins encoded by cdna inserts. this is achieved by the fusion of cdna open reading frames to the t7 gene 10 promoter and protein-coding sequences. the second class, the lambda shlx vectors, allows the generation of large amounts of single-stranded dna or synthetic crna that can be used in ... | 1990 | 2140336 |
| a positive selection vector for cloning high molecular weight dna by the bacteriophage p1 system: improved cloning efficacy. | the bacteriophage p1 cloning system can package and propagate dna inserts that are up to 95 kilobases. clones are maintained in escherichia coli by a low-copy replicon in the p1 cloning vector and can be amplified by inducing a second replicon in the vector with isopropyl beta-d-thiogalactopyranoside. to overcome the necessity of screening clones for dna inserts, we have developed a p1 vector with a positive selection system that is based on the properties of the sacb gene from bacillus amyloliq ... | 1992 | 1549564 |
| identification of cryptic lox sites in the yeast genome by selection for cre-mediated chromosome translocations that confer multiple drug resistance. | the cre recombinase efficiently causes site-specific dna recombination at loxp sites placed into the eukaryotic genome. since the loxp site of phage p1 is 34 base-pairs in size, the natural occurrence of this exact sequence is unlikely in any eukaryotic genome. however, related sequences may exist in eukaryotic genomes that could recombine at low efficiency with an authentic loxp site. this work identifies such cryptic lox sites in the yeast genome using a positive selection procedure that allow ... | 1992 | 1554399 |
| molecular characterization of a trans-acting, positive effector (ipar) of invasion plasmid antigen synthesis in shigella flexneri serotype 5. | a trans-acting, positive effector of invasion plasmid antigen (ipa) synthesis has been identified and mapped on the pwr100 invasion plasmid of shigella flexneri serotype 5 (strain m90t-w). recombinant plasmids carrying this regulatory gene, designated ipar, were found to restore full virulence to a non-invasive ipar::tn5 insertion mutant [m90t-w(phs1042)] that had lost the ability to synthesize four ipa antigens (ipaa, 70 kda; ipab, 62 kda; ipac, 42 kda; and ipad, 37 kda). genetic mapping of the ... | 1990 | 2166210 |
| the bof protein of bacteriophage p1 exerts its modulating function by formation of a ternary complex with operator dna and c1 repressor. | bacteriophage p1 encodes several regulatory elements for the lytic or lysogenic response, which are located in the immc, immi, and immt regions. their products are the c1 repressor of lytic functions with the c1 inactivator protein coi, the c4 repressor of antirepressor synthesis and the modulator protein bof, respectively. we have studied in vitro the interaction of the components of the immc and immt regions with c1-controlled operators using highly purified bof, c1, and coi proteins. bof prot ... | 1992 | 1601883 |
| the c4 repressor of bacteriophage p1 is a processed 77 base antisense rna. | the c4 repressors of the temperate bacteriophages p1 and p7 inhibit antirepressor synthesis and are essential for establishment and maintenance of lysogeny. using in vivo complementation tests we have previously shown that c4 is an antisense rna acting on a target, ant mrna, which is transcribed from the same promoter. here we identify the c4 repressor molecule of p1 as a 77 +/- 1 base rna by mapping its termini and show that the c4 rna in p7 lysogens has the same or a similar size. p1 c4 rna is ... | 1992 | 1620606 |
| a tn3 derivative that can be used to make short in-frame insertions within genes. | a tn3 derivative was constructed to make small in-frame insertions within genes. the transposon contains the ura3 gene, the teta gene, a truncated lacz, and phage p1 loxp recombination sites at either end. insertions that have fused lacz to an open reading frame are lac+ because they express the truncated lacz. in the presence of the phage p1 cyclization recombinase cre, the transposon can delete the ura3, teta, and lacz genes between the two loxp sites. the remaining short imperfect palindrome ... | 1991 | 1647034 |
| gene organization in the multiple dna inversion region min of plasmid p15b of e.coli 15t-: assemblage of a variable gene. | the bacteriophage p1-related plasmid p15b of e. coli 15t- contains a 3.5 kb long region which frequently undergoes complex rearrangements by dna inversion. site-specific recombination mediated by the min dna invertase occurs at six crossover sites and it eventually results in a population of 240 isomeric configurations of this region. we have determined 8.3-kb sequences of the invertible dna and its flanking regions. the result explains how dna inversion fuses variable 3' parts to a constant 5' ... | 1991 | 1945872 |
| generation of a 50,000-member human dna library with an average dna insert size of 75-100 kbp in a bacteriophage p1 cloning vector. | a bacteriophage p1 cloning system that permits the isolation and amplification of cloned dna fragments as large as 100 kbp was described previously. we have now utilized a similar system to generate a 50,000-member human dna library with dna inserts ranging in size from 75 to 100 kbp. two major obstacles were overcome in constructing the library. the first concerned the mcrab restriction system of escherichia coli, which degrades dna containing mec and interferes with the recovery of cloned huma ... | 1990 | 1964591 |
| null mutation in the stringent starvation protein of escherichia coli disrupts lytic development of bacteriophage p1. | as initial steps toward understanding the regulation and function of the stringent starvation protein (ssp) of escherichia coli, we have isolated the ssp gene (encoding ssp), defined the operon in which ssp is found, and created insertion-deletion mutations of the ssp gene in recbc, sbc and recd strains by linear dna transformation. during attempts to move the insertion-deletion structure to other strains by p1 transduction, we found that p1 was unable to form plaques on hosts lacking an intact ... | 1991 | 1721886 |
| the min dna inversion enzyme of plasmid p15b of escherichia coli 15t-: a new member of the din family of site-specific recombinases. | plasmid p15b is a bacteriophage p1-related resident of escherichia coli 15t-. both genomes contain a segment in which dna inversion occurs, although this part of their genomes is not identical. this dna segment of p15b was cloned in a multicopy vector plasmid. like its parent, the resulting plasmid, paw800, undergoes complex multiple dna inversions: this dna inversion system is therefore called min. the min gene, which codes for the p15b min dna invertase, can complement the p1 cin recombinase g ... | 1990 | 2215218 |
| characterization of bacteriophage p1 library containing inserts of drosophila dna of 75-100 kilobase pairs. | a multiple-hit bacteriophage p1 library containing dna fragments from drosophila melanogaster in the size range 75-100 kb was created and subjected to a preliminary evaluation for completeness, randomness, fidelity, and clone stability. this p1 library presently contains 3840 individual clones, or approximately two genome equivalents. the library was screened with a small set of unique-sequence test probes, and clones containing the sequences have been recovered. in situ hybridization with saliv ... | 1991 | 1764967 |
| s1 nuclease transcript mapping using sequenase-derived single-stranded probes. | we report here a simple method for the production of high specific activity single-stranded dna probes for s1 nuclease transcript mapping. plasmid dna is used as in vitro dna templates for probe production by primer extension using sequenase. this allows the production of long single-stranded probes without the need to subclone restriction fragments into m13 vectors. the mapping of the 5' ends of the phage p1 mod gene transcripts is shown as an example. | 1991 | 1867849 |
| bacteriophage p1 gene 10 encodes a trans-activating factor required for late gene expression. | amber mutants of bacteriophage p1 were used to identify functions involved in late regulation of the p1 lytic growth cycle. a single function has been genetically identified to be involved in activation of the phage-specific late promoter sequence ps. in vivo, p1 gene 10 amber mutants fail to trans activate a lacz operon fusion under the transcriptional control of promoter ps. several p1 segments, mapping around position 95 on the p1 chromosome, were cloned into multicopy plasmid vectors. some o ... | 1991 | 1917870 |
| bacteriophage p1 bof protein is an indirect positive effector of transcription of the phage bac-1 ban gene in some circumstances and a direct negative effector in other circumstances. | previous genetic studies have suggested that the bof protein of bacteriophage p1 can act as both a negative and a positive regulator of phage gene expression: in bof-1 prophages, the ref gene and a putative phage ssb gene are derepressed, but expression of an operator-semiconstitutive variant of the phage ban gene (bac-1) is markedly reduced. an explanation of this apparent duality is suggested by recent reports that bof is a corepressor of genes that are regulated by the phage c1 repressor, inc ... | 1991 | 1917872 |
| the sim gene of escherichia coli phage p1: nucleotide sequence and purification of the processed protein. | the sim gene of bacteriophage p1 causes exclusion of a superinfecting p1 phage. we determined the nucleotide sequence of a 1.9-kb dna fragment that, in plasmids, causes sim phenotype. there are two open reading frames within this region for proteins of 82 and 259 amino acids. a 1.3-kb fragment containing the larger open reading frame was inserted into an expression vector. induced cells carrying the hybrid plasmid, termed pbd5, were not infected by phage p1 and produced a 24-kda protein and, to ... | 1990 | 2327075 |
| the bof gene of bacteriophage p1: dna sequence and evidence for roles in regulation of phage c1 and ref genes. | the c1 repressor of bacteriophage p1 acts via 14 or more distinct operators. this repressor represses its own synthesis as well as the synthesis of other gene products. previously, mutation of an auxiliary regulatory gene, bof, has been shown to increase expression of some c1-regulated p1 genes (e.g., ref) but to decrease expression of others (e.g., ban). in this study the bof gene was isolated on the basis of its ability to depress stimulation of escherichia coli chromosomal recombination by th ... | 1990 | 2345146 |
| genetic manipulation of salmonella serotype bovismorbificans to aromatic-dependence and evaluation of its vaccine potential in mice. | the generation of smooth aromatic-dependent salmonella serotype bovismorbificans (group c2, o6, 8) from a smooth wild-type parent strain by transduction with phage p1, and conjugation with salmonella serotype typhimurium carrying f'-8gal is described. the smooth aromatic-dependent s. serotype bovismorbificans was non-lethal for mice at an oral challenge dose of 2 x 10(9) cfu (equivalent to 200 ld50 of the parent, wild-type strain). the safety of the auxotrophic mutant was further substantiated b ... | 1991 | 1990138 |
| escherichia coli ppgpp synthetase ii activity requires spot. | escherichia coli has two enzymes catalyzing the synthesis of guanosine tetraphosphate (ppgpp), designated ppgpp synthetase i (psi = rela) and ii (psii), whose activities are regulated differently. until now, the gene for psii had not been identified. here, an e. coli rela1 strain that expresses lacz from an rrnb p1 promoter was used to screen mutants with increased beta-galactosidase activity on 5-bromo-4-chloro-3-indoyl beta-d-galactoside indicator plates at 30 degrees c. about 15% of the mutan ... | 1991 | 2005135 |
| organization of the bacteriophage p1 tail-fibre operon. | the revised sequence of a bacteriophage p1 dna fragment containing the 5' end of the tail-fibre gene, gene 19, revealed that this gene is closely preceded by another open reading frame (orf) of 432 bp. we have designated this orf as gene r. the tail-fibre gene and gene r are transcriptionally and translationally coupled. thus, the tail-fibre operon of bacteriophage p1 consists of three genes: gene r, gene 19 (or gene s) and gene u. | 1989 | 2526777 |
| nucleotide sequence of the replication region of the marine rhodobacter plasmid prd31. | the minimum region required for replication of the marine rhodobacter endogenous plasmid prd31 has been sequenced. this region is located on a 1367-bp hincii-psti restriction fragment and is 62% rich in g-c base pairs. a region homologous to the bacteriophage p1 repa promoter, which overlaps two inverted repeats, has been identified. plasmids with mutations in this 1367-bp region could not replicate in marine rhodobacter hosts. this is the first identified replication origin of a photosynthetic ... | 1991 | 2044764 |
| mutational analysis of the bacteriophage p1 late promoter sequence ps. | the bacteriophage p1 late promoter sequence ps controls the expression of the genes in the tail-fibre operon. transcription from ps only occurs during the second half of the p1 vegetative growth cycle and is positively regulated by the product of the phage gene 10. in this study degenerate oligonucleotides were used as primers in site-directed mutagenesis reactions in order to construct a large set of point mutations within the late promoter sequence ps. a total of 35 independent single point mu ... | 1992 | 1447774 |
| general method for site-directed mutagenesis in escherichia coli o18ac:k1:h7: deletion of the inducible superoxide dismutase gene, soda, does not diminish bacteremia in neonatal rats. | a defined deletion in the escherichia coli k-12 soda gene (encoding manganese-superoxide dismutase) linked to a nontransposable selectable marker was generated by transposon tn5 insertion in combination with in vitro mutagenesis. this mutant allele was used to replace the wild-type soda gene in an e. coli clinical isolate of serotype o18ac:k1:h7 by bacteriophage p1 transduction. the o18ac:k1:h7 soda mutant contained no manganese-superoxide dismutase and no hybrid manganese-iron-superoxide dismut ... | 1989 | 2543632 |
| transcriptional analysis of the restriction and modification genes of bacteriophage p1. | bacteriophage p1 res and mod genes encode the restriction and modification polypeptides of the type iii restriction enzyme ecop1. northern blot analysis using res- and mod-specific probes revealed the presence of two separate transcripts in strains harbouring the ecop1 restriction and modification genes. furthermore, by constructing a series of fusions with a promoter less lacz gene, we show that both the res and mod genes are transcribed from separate promoters. a more detailed investigation of ... | 1991 | 2046552 |
| uncoupler resistance in e. coli tuv and cuv is due to the exclusion of uncoupler by the outer membrane. | the uncoupler resistant bacterial strains e. coli tuv and cuv share the high deoxycholate sensitivity of the parent strain, doc s. however, both tuv and cuv show greater resistance than doc s to other detergents. measurement of the periplasmic volume indicates that the outer membrane of doc s is freely permeable to both tpp+ and hydroxymethylinulin. tuv and cuv are able to exclude these compounds. edta treatment was necessary prior to measuring membrane potential in tuv and cuv. under conditions ... | 1990 | 2118805 |
| isolation and characterization of mutants affected in the expression of the nar operon escherichia coli. | in the nitrate reductase system of escherichia coli, the maximal expression of the nar operon is obtained under anaerobiosis in the presence of nitrate. mudl (ap,lac) insertion mutants, which only grew on lactose anaerobically if supplemented with nitrate were mapped at the chlc locus at min 27 of the map. in these fusion strains which lack benzyl viologen dependent nitrate reductase (nr) activity as well as the formiate-linked nr activity, the synthesis of beta-galactosidase reflects the regula ... | 1990 | 2135555 |
| c1 repressor of phage p1 is inactivated by noncovalent binding of p1 coi protein. | the temperate phage p1 encodes two genes whose products antagonize the action of the phage's c1 repressor of lytic functions, namely a distantly linked antirepressor gene, ant, and a closely linked c1 inactivator gene, coi. starting with an inducible coi-recombinant plasmid, coi protein was overproduced and purified to near homogeneity. by using a dna mobility shift assay we demonstrate that coi protein inhibits the operator binding of the c1 repressors of the closely related p1 and p7 phages. c ... | 1992 | 1740459 |
| highly efficient generation of recombinant baculoviruses by enzymatically medicated site-specific in vitro recombination. | we have used the cre-lox system of bacteriophage p1 to develop a highly efficient in vitrosystem for construction of recombinant baculoviruses. a positive visual selection has been included to make identification of recombinant viral progeny rapid and straightforward. we report recombination frequencies as high as 5 x 10(7) recombinants/micrograms starting plasmid dna and under certain conditions, up to 50% of the viral progeny are recombinants. genes inserted into the baculovirus genome can be ... | 1992 | 1741284 |
| generation of aromatic-dependent salmonella havana and evaluation of its immunogenic potential in mice and sheep. | the generation of aromatic-dependent (aro-) salmonella havana (group g2, 01, 13, 23) from a smooth wild-type parent strain by transduction with phage p1 is reported. mice immunized with this live aro- s. havana strain (cs234) by the intraperitoneal (i.p.) route were protected against challenge with wild-type s. havana, whereas those immunized by the oral route were not. mice immunized with two doses of formalin-killed aro- s. havana by the i.p. route were also unprotected, in spite of high antib ... | 1991 | 1746157 |
| plasmid cloning vectors for the conjugal transfer of dna from escherichia coli to streptomyces spp. | we have constructed cloning vectors for the conjugal transfer of dna from escherichia coli to streptomyces spp. all vectors contain the 760-bp orit fragment from the incp plasmid, rk2. transfer functions need to be supplied in trans by the e. coli donor strain. we have incorporated into these vectors selectable antibiotic-resistance markers (amr, thr, spr) that function in streptomyces spp. and other features that should allow for: (i) integration via homologous recombination between cloned dna ... | 1992 | 1628843 |
| gene transfer with subsequent removal of the selection gene from the host genome. | a general method of gene transfer that does not leave behind a selectable marker in the host genome is described. a luciferase gene was introduced into the tobacco genome by using the hygromycin phosphotransferase gene (hpt) as a linked selectable marker. flanked by recombination sites from the bacteriophage p1 cre/lox recombination system, the hpt gene was subsequently excised from the plant genome by the cre recombinase. the cre-catalyzed excision event in the plant genome was precise and cons ... | 1991 | 1660141 |
| the c1 repressor inactivator protein coi of bacteriophage p1. cloning and expression of coi and its interference with c1 repressor function. | the immc region of bacteriophage p1 contains the c1 repressor gene and its upstream region with four c1-controlled operators and four open reading frames. a c1 inactivator gene, coi, was defined by mutations in immc that suppress the virulence of the p1virc mutation. the exact location of the coi gene was not known (scott, j.r. (1980) curr. top. microbiol. immunol. 90, 49-65). when a variety of p1 immc fragments were inserted into an expression vector, a gene product was inducible for the open r ... | 1990 | 2211669 |
| a bacteriophage p1-encoded modulator protein affects the p1 c1 repression system. | bacteriophage p1 encodes a tripartite immunity system composed of the immc, immi, and immt region. their basic genetic elements are the c1 repressor of lytic functions, the c4 repressor which negatively regulates antirepressor synthesis, and the bof gene, respectively. the function of the latter will be described here. we have cloned and sequenced the bof gene from p1 wild type and a p1 bof amber mutant. based on the position of a tag codon of the bof amber mutant the bof wild type gene was loca ... | 1990 | 2211715 |
| [transduction of chromosome and plasmid markers of bacteriophage p1 in pseudotuberculosis pathogen]. | a clone of bacteriophage p1 clr100 cml has been isolated capable of the general transduction in the cells of pseudotuberculosis causative agent. the genetic transfer of the 6 md pesticinogenicity plasmid by the bacteriophage has been used as a model to demonstrate the possibility of transduction. the bacteriophage used has been shown to be efficient in interspecies transduction between yersinia. | 1990 | 2215519 |
| cleavage of the bacteriophage p1 packaging site (pac) is regulated by adenine methylation. | the packaging of bacteriophage pi dna is initiated when the phage packaging site (pac) is recognized and cleaved and continues until the phage head is full. we have previously shown that pac is a 162-base-pair segment of p1 dna that contains seven dna adenine methyltransferase methylation sites (5'-gatc). we show here that cleavage of pac is methylation sensitive. both in vivo and in vitro experiments indicate that methylated pac is cleavable, whereas unmethylated pac is not. moreover, dna isola ... | 1990 | 2236019 |
| dna specificity of the cre recombinase resides in the 25 kda carboxyl domain of the protein. | the cre protein of bacteriophage p1 is a 38.5 kda site-specific recombinase that belongs to the int family of recombination proteins. cre acts by binding specifically to a 34 base-pair sequence, lox, where it carries out recombination. a limited chymotryptic digest of cre resulted in two fragments of sizes 25 and 13.5 kda, respectively. the sequence of the amino terminus of the purified 25 kda peptide demonstrates that this peptide represents the carboxyl-terminal portion of the cre protein. a t ... | 1990 | 2266559 |
| targeted insertion of exogenous dna into the eukaryotic genome by the cre recombinase. | cre is a 38-kd protein from bacteriophage p1 that catalyzes site-specific recombination between 34-bp loxp sequences. our previous work has shown that cre can perform site-specific excisive recombination not only in prokaryotes, but also in eukaryotes such as yeast and cultured mammalian cells. in this work we show that intermolecular cre-mediated recombination can specifically direct the integration of a loxp-containing circular dna into a chromosomal loxp site, both in yeast and in mammalian c ... | 1990 | 2288914 |
| sequence analysis of the inversion region containing the pilin genes of moraxella bovis. | moraxella bovis epp63 is able to produce two antigenically distinct pili called q and i pili (previously called beta and alpha pili). hybridization studies have shown that the transition between the types is due to inversion of a 2.1-kilobase segment of chromosomal dna. we present the sequence of a 4.1-kilobase region of cloned dna spanning the entire inversion region in orientation 1 (q pilin expressed). comparison of this sequence with the sequence of the polymerase chain reaction-amplified ge ... | 1990 | 2403542 |
| bacteriophage p1 cloning system for the isolation, amplification, and recovery of dna fragments as large as 100 kilobase pairs. | the development of a bacteriophage p1 cloning system capable of accepting dna fragments as large as 100 kilobase pairs (kbp) is described. the vectors used in this system contain a p1 packaging site (pac) to package vector and cloned dna into phage particles, two p1 loxp recombination sites to cyclize the packaged dna once it has been injected into a strain of escherichia coli containing the p1 cre recombinase, a kanr gene to select bacterial clones containing the cyclized dna, a p1 plasmid repl ... | 1990 | 2404272 |
| properties of new escherichia coli hfr strains constructed by integration of psc101-derived conjugative plasmids. | conjugative temperature-sensitive plasmids were derived from psc101. these plasmids are useful in genetic analysis for two reasons: (i) they render possible the construction of new hfr lines by plasmid integration at predetermined chromosomal loci via tn10 inverse transposition, and (ii) the hfr characters are transducible via bacteriophage p1. we also showed that replication from psc101 origin is deleterious for the plasmid-chromosome fusion. | 1990 | 2155201 |
| [interactions of the phytopathogenic bacteria erwinia with phage p1 crl100 cml]. | the bacteriophage p1 cm clr100 lysogenises the bacteria e. chrysanthemi, e. aroideae, e. atroseptica being localized in the cytoplasm, replicating but causing no cell lysis. the prophage induction results in transformation of the lysogenic bacteria e. chrysanthemi into nonviable filamentous cells. however, a portion of cells gets rid of the prophage and gives rise to normal heritage inheritors permitting to use the bacteriophage as an efficient vehicle for introducing the transposons into the ch ... | 1990 | 2159108 |
| site-directed recombination in the genome of transgenic tobacco. | the plant genome responds to the bacteriophage p1-derived loxp-cre site-specific recombination system. recombination took place at loxp sites stably integrated in the tobacco genome, indicating that the cre recombinase protein, expressed by a chimeric gene also stably resident in the genome, was able to enter the nucleus and to locate a specific 34 bp dna sequence. an excisional recombination event was monitored by the acquisition of kanamycin resistance, which resulted from the loss of a polyad ... | 1990 | 2176714 |
| three escherichia coli heat shock proteins are required for p1 plasmid dna replication: formation of an active complex between e. coli dnaj protein and the p1 initiator protein. | dna containing the plasmid origin of bacteriophage p1 is replicated in vitro by a protein fraction prepared from uninfected escherichia coli supplemented with purified p1 repa protein. it has previously been shown that the reaction required the e. coli dnaa initiator protein, the dnab helicase, dnac protein, rna polymerase, and dna gyrase. i show here that three e. coli heat shock proteins, dnaj, dnak, and grpe, are directly involved in p1 plasmid replication. purified dnaj, dnak, and grpe prote ... | 1990 | 2181445 |
| linkage map of escherichia coli k-12, edition 8. | the linkage map of escherichia coli k-12 depicts the arrangement of genes on the circular chromosome of this organism. the basic units of the map are minutes, determined by the time-of-entry of markers from hfr into f- strains in interrupted-conjugation experiments. the time-of-entry distances have been refined over the years by determination of the frequency of cotransduction of loci in transduction experiments utilizing bacteriophage p1, which transduces segments of dna approximately 2 min in ... | 1990 | 2194094 |
| intra- and intermolecular site-specific recombination in plant cells mediated by bacteriophage p1 recombinase. | a site-specific recombination system has many potential uses for rearranging genetic material in higher eukaryotic cells: for example, the control of gene expression by deletion or inversion of dna segments, the clustering of transgenic constructs via site-specific integration, and the generation of chromosomal translocations. in this report, we describe a first step towards the application of a site-specific recombination system in plant cells. by use of a transient assay, we demonstrate that t ... | 1990 | 2205542 |
| growth-rate-dependent expression and cloning of gnd alleles from natural isolates of escherichia coli. | 6-phosphogluconate dehydrogenase (6pgd), encoded by gnd, is highly polymorphic among isolates of escherichia coli form natural populations. as a means of characterizing the growth-rate-dependent regulation of the level of 6pgd, five gnd alleles, including the e. coli b/r allele, were crossed into e. coli k-12 with bacteriophage p1. in each of the isogenic strains, the level of 6pgd was two- to threefold higher in cells grown on glucose than in cells grown on acetate. the level of enzyme activity ... | 1988 | 2826398 |
| the c1 repressor of bacteriophage p1. isolation and characterization of the repressor protein. | the c1 repressor gene of bacteriophage p1 is located on p1 dna ecori fragment 7 (sternberg, n. (1979) virology 96, 129-142). subfragments of p1 dna ecori fragment 7 were cloned into expression vectors, and the c1 repressor protein from p1 wild-type phage and a revertant of a temperature-sensitive repressor mutant were overproduced in escherichia coli and purified to near-homogeneity. the decreased electrophoretic mobility of p1 dna bamhi fragment 9 in the presence of appropriate protein fraction ... | 1988 | 2826478 |
| mutational analysis of a prokaryotic recombinational enhancer element with two functions. | the site-specific dna inversion system cin encoded by the bacteriophage p1 consists of a recombinase, two inverted crossing-over sites and a recombinational enhancer. the latter approximately 75 bp long genetic element is bifunctional due to its location within the 5' part of the cin gene encoding the recombinase. in order to determine the essential nucleotides for each of its two biological functions we randomly mutated the recombinational enhancer sequence sis(p1) and analysed both functions o ... | 1989 | 2656257 |
| genetic analysis of the lytic replicon of bacteriophage p1. ii. organization of replicon elements. | the region of bacteriophage p1 dna containing a lytic (vegetative) replicon has been identified by cloning p1 fragments into a phage lambda vector. we present the sequence of that replicon. using a novel fusion vector containing two p1 loxp recombination sites, we have developed a transformation assay for replicon function and have used that assay to identify some of the components of the p1 lytic replicon. among those components is a transcription promoter, p53, whose activity is essential for ... | 1989 | 2661830 |
| development of an auxotrophic oral live shigella flexneri vaccine. | an oral live attenuated shigella flexneri vaccine candidate strain was constructed by making it auxotrophic and dependent on aromatic metabolites not available in mammalian tissues. an arod gene of escherichia coli k12 strain nk 5131, inactivated by insertion in it of the tn 10 transposon, was transduced using phage p1 into a virulent s. flexneri serotype y strain (sfl 1) isolated from a patient with bacillary dysentery. one of the transductant strains sfl 114 was found to invade hela cells in v ... | 1988 | 2838986 |
| structure and regulation of the lytic replicon of phage p1. | three replicons, r, l and p1dr, have been previously identified in bacteriophage p1, but only the r (or plasmid) replicon has been functionally and structurally characterized. evidence is provided here that the l-replicon is the principal replicon used for dna replication during the lytic cycle. the l-replicon (exclusive of its promoter) is shown to be contained within a 1093-base-pair dna segment that includes a 281-codon open reading frame, designated repl. l-replicon function requires transcr ... | 1989 | 2661831 |
| structural and functional analysis of tn4430: identification of an integrase-like protein involved in the co-integrate-resolution process. | the 4149-bp transposon tn4430 from bacillus thuringiensis is delineated by 38-bp inverted repeats and codes for a 113-kd protein that shares homology with the transposases (tnpa) of tn3, tn21 and tn501. through transpositional recombination, this protein generates the formation of co-integrates between both donor and target replicons, with duplication of tn4430 molecules. these features are characteristic of transposons of the tn3 family (class ii elements). the second step of the transposition ... | 1988 | 2842151 |
| participation of the lytic replicon in bacteriophage p1 plasmid maintenance. | p1 bacteriophage carries at least two replicons: a plasmid replicon and a viral lytic replicon. since the isolated plasmid replicon can maintain itself stably at the low copy number characteristic of intact p1 prophage, it has been assumed that this replicon is responsible for driving prophage replication. we provide evidence that when replication from the plasmid replicon is prevented, prophage replication continues, albeit at a reduced rate. the residual plasmid replication is due to incomplet ... | 1989 | 2670895 |
| involvement of dnak protein in mini-f plasmid replication: temperature-sensitive seg mutations are located in the dnak gene. | the seg mutants (seg-1 and seg-2) of escherichia coli cannot support the replication of the f factor and mini-f plasmids at 42 degrees c. we cloned the wild-type e. coli chromosomal dna fragment complementing the seg-1 and seg-2 mutations and found that both mutations were complemented by the wild-type dnak gene coding for a heat shock protein. transduction with phage p1 indicated that the seg-2 mutation is located at about 0.3 min in the region containing the dnak gene in the order trpr--thra-- ... | 1989 | 2674651 |
| the c1 repressor of bacteriophage p1 operator-repressor interaction of wild-type and mutant repressor proteins. | the c1 repressor gene of bacteriophage p1 and the temperature-sensitive mutants p1c1.100 and p1c1.162 was cloned into an expression vector and the repressor proteins were overproduced. a rapid purification procedure was required for the isolation of the thermolabile repressor proteins. identification of the highly purified protein of an apparent molecular weight of 33,000 as the product of the c1 gene was verified by (i) the coincidence of partial amino acid sequences determined experimentally t ... | 1989 | 2678004 |
| envm genes of salmonella typhimurium and escherichia coli. | conjugation and bacteriophage p1 transduction experiments in escherichia coli showed that resistance to the antibacterial compound diazaborine is caused by an allelic form of the envm gene. the envm gene from salmonella typhimurium was cloned and sequenced. it codes for a 27,765-dalton protein. the plasmids carrying this dna complemented a conditionally lethal envm mutant of e. coli. recombinant plasmids containing gene envm from a diazaborine-resistant s. typhimurium strain conferred the drug r ... | 1989 | 2687243 |
| characterization of mutations of the bacteriophage p1 mod gene encoding the recognition subunit of the ecop1 restriction and modification system. | this study characterized several mutations of the bacteriophage p1 mod gene. this gene codes for the subunit of the ecop1 restriction enzyme that is responsible for dna sequence recognition and for modification methylation. we cloned the mutant mod genes into expression vectors and purified the mutant proteins to near homogeneity. two of the mutant mod genes studied were the c2 clear-plaque mutants described by scott (virology 41:66-71, 1970). these mutant proteins can recognize ecop1 sites in d ... | 1989 | 2708308 |
| three additional operators, op21, op68, and op88, of bacteriophage p1. evidence for control of the p1 dam methylase by op68. | the repressor of bacteriophage p1, encoded by the c1 gene, is responsible for maintaining the p1 prophage in the lysogenic state. previously, 11 c1 repressor binding sites or operators scattered over the whole genome of p1 have been found. from sequence analysis an asymmetric, 17-base pair consensus sequence, attgctctaataaattt, was derived. using a synthetic 15-base-long oligodeoxyribonucleotide as operator probe, we have identified three additional operators. we have mapped the operators at the ... | 1989 | 2536753 |
| endonuclease iii (nth) mutants of escherichia coli. | two strains that overproduce endonuclease iii were found in a colony bank containing hybrid cole1-escherichia coli plasmids. the enzyme was identified in crude extracts by the degradation of partially depyrimidinated dna in the presence of edta, by its sedimentation velocity, and by its associated thymine glycol-dna glycosylase activity. an insertion mutation was produced by cloning the kanamycin-resistance gene of tn5 into the plasmid copy of the nth gene. the mutation was then transferred to t ... | 1985 | 2982160 |
| cloning and complementation analysis of the "frizzy" genes of myxococcus xanthus. | fruiting-body formation in myxococcus xanthus involves the aggregation of cells into raised mounds, where they sporulate. "frizzy" mutants fail to aggregate into mounds, but rather aggregate into "frizzy" filaments (d.r. zusman 1982). the frizzy mutations (frz) were found to be genetically linked. the region of dna carrying the frz genes was cloned in escherichia coli by selecting for the kanamycin resistance element present on a transposon tn5 insertion linked to the frz genes. phage p1 mediate ... | 1985 | 2984519 |
| bacteriophage p1 derivatives unaffected in their growth by a large inversion or by is insertions at various locations. | several plaque-forming phage p1 derivatives carrying dna rearrangements associated with is elements are described. they have is1, is3 and is5 inserted in four distinct locations, all of which are non-essential regions for phage p1 propagation. one derivative carries a genome segment, inverted relative to the one in the p1 wild-type genome, between two inverted copies of is1. the inverted dna segment spans about 23 kb of the 90 kb long p1 genome and it includes the invertible c segment. this phag ... | 1985 | 2985738 |
| stimulation of is1 excision by bacteriophage p1 ref function. | lysogenization by a c1ts variant of coliphage p1, p1c1.100, markedly increased the frequency of reversion of a galt::is1 mutation. the formation of gal+ colonies presumably occurs by microhomologous recombination between the 9-base-pair repeats in galt (cgccgctac) generated by the transposition of is1. the responsible p1 gene, ref, has been cloned and sequenced. ref encodes a 22.8-kilodalton protein and is located near the p1 site-specific recombination function, cre. expression of ref was repre ... | 1989 | 2542224 |
| characterization of in vitro constructed is30-flanked transposons. | in order to facilitate functional studies on the mobile genetic element is30, a resident of the escherichia coli chromosome, transposon structures with two copies of is30 flanking the chloramphenicol-resistance gene cat were constructed in vitro. transposons containing is30 as direct repeats (tn2700 and tn2702) transpose from multicopy plasmids into the genome of phage p1-15, thus giving rise to special transduction for cat with frequencies between 10(-5) and 10(-8)/plaque-forming unit. in contr ... | 1989 | 2546856 |
| cloning of the vibrio cholerae reca gene and construction of a vibrio cholerae reca mutant. | a recombinant plasmid carrying the reca gene of vibrio cholerae was isolated from a v. cholerae genomic library, using complementation in escherichia coli. the plasmid complements a reca mutation in e. coli for both resistance to the dna-damaging agent methyl methanesulfonate and recombinational activity in bacteriophage p1 transductions. after determining the approximate location of the reca gene on the cloned dna fragment, we constructed a defined reca mutation by filling in an xbai site locat ... | 1986 | 3005236 |
| formation of small circular dna molecules via an in vitro site-specific recombination system. | the cre-lox site-specific recombination system of bacteriophage p1 has been used to investigate the role of dna flexibility in recombination. we have determined that a minimal distance of 82 bp must separate two loxp sites located on the same dna molecule to allow these sites to undergo intramolecular recombination with one another. as a result of recombination, dna circles as small as 116 bp have been produced. in addition, we have demonstrated that the nuclease bal 31 recognizes distortions in ... | 1985 | 3007297 |
| enhancement of escherichia coli plasmid and chromosomal recombination by the ref function of bacteriophage p1. | the ref activity of phage p1 enhances recombination between two defective lacz genes in the escherichia coli chromosome (lac- x lac- recombination). plasmid recombination, both lac- x lac- and tet- x tet-, was measured by transformation of reca strains, and was also assayed by measurement of beta-galactosidase. the intracellular presence of recombinant plasmids was verified directly by southern blotting. ref stimulated recombination of plasmids in rec+ and rec(bcd) cells by 3-6-fold, and also th ... | 1989 | 2557261 |
| the groes and groel heat shock gene products of escherichia coli are essential for bacterial growth at all temperatures. | the products of the groes and groel genes of escherichia coli, constituting the groe operon, are known to be required for growth at high temperature (42 degrees c) and are members of the heat shock regulon. using a genetic approach, we examined the requirement for these gene products for bacterial growth at low temperature (17 to 30 degrees c). to do this, we constructed various groes groel heterodiploid derivative strains. by inactivating one of the groe operons by a polar insertion, it was sho ... | 1989 | 2563997 |
| type 1 pili are not necessary for colonization of the streptomycin-treated mouse large intestine by type 1-piliated escherichia coli f-18 and e. coli k-12. | escherichia coli f-18, an excellent colonizer of the streptomycin-treated mouse large intestine, produces type 1 pili. e. coli f-18 fima-, type 1 pilus negative, and e. coli f-18 fimh-, type 1 pilus positive but adhesin negative, were constructed by bacteriophage p1 transduction of defective fima and fimh genes from the e. coli k-12 strains orn151 and orn133, respectively, into e. coli f-18. adhesion of e. coli f-18 to an immobilized mannose-bovine serum albumin glycoconjugate was about sixfold ... | 1989 | 2570752 |
| organization of the immunity region immi of bacteriophage p1 and synthesis of the p1 antirepressor. | the immi region of bacteriophage p1 includes the ant/reb gene, which encodes the antirepressor protein, and the c4 gene, which encodes a repressor molecule that negatively regulates antirepressor synthesis. the antirepressor interferes with the activity of the p1 repressor of lytic function, the product of the c1 gene. we have determined the dna sequences of the immi region of p1 wild-type and the mutants virs, ant16, ant17, and reb22. using suitable p1 immi dna subfragments cloned into a vector ... | 1989 | 2585500 |
| ban operon of bacteriophage p1. mutational analysis of the c1 repressor-controlled operator. | the repressor of bacteriophage p1, encoded by the c1 gene, represses the phage lytic functions and is responsible for maintaining the p1 prophage in the lysogenic state. the c1 repressor interacts with at least 11 binding sites or operators widely scattered over the p1 genome. from these operators, a 17 base-pair asymmetric consensus sequence, attgctctaataaattt, was derived. here, we show that the operator, op72 of the p1ban operon consists of two overlapping 17 base-pair sequences a and b formi ... | 1989 | 2647997 |
| [mutagenic effect during transduction of (gm-km)r markers of the r323 plasmid in yersinia pestis]. | genes of resistance to some aminoglycoside antibiotics from plasmid r323 were transduced by bacteriophage p1 cml clr100 ts in yersinia pestis. the resistance markers were capable of insertion into the chromosome or plasmid in the recipient cells causing the mutagenic effect. the results obtained suggest the transposon nature of plasmid fragment coding for gentamicin-kanamycin resistance. | 1985 | 3025695 |
| bent dna is needed for recombinational enhancer activity in the site-specific recombination system cin of bacteriophage p1. the role of fis protein. | a series of recombinational enhancer mutants was constructed by manipulating the clai site between the two fis binding sites of the hin enhancer. these mutants include insertions from two to 12 base-pairs and two deletions of one or two base-pairs. recombinational enhancer activity was found only with four mutants carrying either a four base-pair substitution, ten base-pair insertions or a one base-pair deletion, respectively; two other ten base-pair insertion mutants, however, were inactive, al ... | 1989 | 2648006 |
| a mutational analysis of the bacteriophage p1 cin recombinase gene: intragenic complementation. | bacteriophage p1 encodes a site-specific recombinase, cin, which regulates the alternate expression of tail fibre genes by inverting a dna segment. to define regions of cin important for the recombination process, we have isolated and characterised 24 different mutations of the cin gene. most of these mutations affected amino acids that are highly conserved in other related recombinases. some of these mutants complement each other in vivo. this intragenic complementation could be due to the asse ... | 1989 | 2651879 |
| isolation of a formamidopyrimidine-dna glycosylase (fpg) mutant of escherichia coli k12. | the fpg+ gene of escherichia coli coding for formamidopyrimidine-dna glycosylase was previously cloned on a multicopy plasmid. the plasmid copy of the fpg+ gene was inactivated by cloning a kanamycin resistance gene into the open reading frame, yielding the fpg-1::knr mutation. this mutation was transferred to the chromosome in the following steps: (i) linearization of the plasmid bearing the fpg-1::knr mutation and transformation of competent bacteria (recb recc sbcb); (ii) selection for chromo ... | 1989 | 2651883 |
| type iii dna restriction and modification systems ecop1 and ecop15. nucleotide sequence of the ecop1 operon, the ecop15 mod gene and some ecop1 mod mutants. | this paper presents the nucleotide sequence of the mod-res operon of phage p1, which encodes the two structural genes for the ecop1 type iii restriction and modification system. we have also sequenced the mod gene of the allelic ecop15 system. the mod gene product is responsible for binding the system-specific dna recognition sequences in both restriction and modification; it also catalyses the modification reaction. a comparison of the two mod gene product sequences shows that they have conserv ... | 1988 | 2837577 |
| transposition of tn4551 in bacteroides fragilis: identification and properties of a new transposon from bacteroides spp. | tn4551, a clindamycin resistance (ccr) transposon from the r plasmid pbi136, was cloned onto an escherichia coli-bacteroides shuttle vector which could replicate normally in e. coli but was maintained unstably in bacteroides fragilis. to aid in cloning and to ensure maintenance of tn4551 in e. coli, a kanamycin resistance determinant (kmr) was inserted in the transposon. the transposon-bearing shuttle vector pfd197 was transformed into b. fragilis 638, and putative insertions of tn4551::kmr were ... | 1987 | 3038840 |
| site-specific dna recombination in mammalian cells by the cre recombinase of bacteriophage p1. | the cre protein encoded by the coliphage p1 is a 38-kda protein that efficiently promotes both intra- and intermolecular synapsis and recombination of dna both in escherichia coli and in vitro. recombination occurs at a specific site, called lox, and does not require any other protein factors. the cre protein is shown here also to be able to cause synapsis of dna and site-specific recombination in a mammalian cell line. a stable mouse cell line was established that expresses the cre protein unde ... | 1988 | 2839833 |
| localization of stx, a determinant essential for high-level production of shiga toxin by shigella dysenteriae serotype 1, near pyrf and generation of stx transposon mutants. | hfr strains of shigella dysenteriae serotype 1 were constructed by transient integration of an rp4 plasmid derivative carrying transposon tn501 into the shigella chromosome through tn501-mediated cointegration. the hfr strains were mated with escherichia coli k-12 recipients carrying various auxotrophic markers, and e. coli recombinants which had received prototrophic shigella genes were selected. some of the e. coli transconjugants produced high levels of a cytotoxin which was neutralized by bo ... | 1987 | 3040592 |
| use of a biotinylated dna probe to detect bacteria transduced by bacteriophage p1 in soil. | presumptive bacteriophage p1 transductants of escherichia coli, isolated from soil inoculated with lysates of transducing phage p1 and e. coli, were confirmed to be lysogenic for phage p1 by hybridization with a biotinylated dna probe prepared from the 1.2-kilobase-pair hindiii 3 fragment of bacteriophage p1. no p1 lysogens of indigenous soil bacteria were detected with the dna probe. the sensitivity and specificity of the dna probe were assessed with purified and dot blot dna, respectively. in ... | 1989 | 2930170 |
| construction of an ordered overlapping library of bacteriophage p1 dna in phage vector lambda d69. | a library of bacteriophage p1 dna was constructed in the phage vector lambda d69. the dna of some 150 randomly chosen lambda-p1 hybrid phages containing p1 dna fragments 5-10 kb in size was analyzed by restriction endonuclease digestion using enzymes ecori, bglii, and bamhi that cleave p1 dna at known positions on the physical map of p1. approximately one third of the phages contained p1 dna inserts having two or more restriction sites for any one of these enzymes, thus allowing the location of ... | 1987 | 2964385 |
| crossover sites cix for inversion of the invertible dna segment c on the bacteriophage p7 genome. | the bacteriophage p7 genome contains an invertible dna segment called c which determines its host range. p7 c(+) phages produce plaques on escherichia coli k12. the c segment consists of a 3-kb unique sequence and 0.62-kb inverted repeats of which one carries an internal 0.2-kb deletion. this deletion has been mapped within the right inverted repeat in the c(+) orientation. the crossover sites cix for inversion of the c segment do not map at the inside boundaries of the inverted repeats, as had ... | 1985 | 2998011 |
| bacteriophage p1 cre-loxp site-specific recombination. site-specific dna topoisomerase activity of the cre recombination protein. | site-specific recombination in bacteriophage p1 occurs between two loxp sites in the presence of the cre recombination protein. the structure of the 34-base pair loxp site consists of two 13-base pair inverted repeats separated by an 8-base pair spacer region. a mutation in the loxp site has been constructed which deletes one of the internal bases of the spacer region at the axis of dyad symmetry. this mutant loxp site shows a 10-fold reduction in recombination activity with a wild-type site bot ... | 1986 | 3001054 |
| genetic analysis of the lytic replicon of bacteriophage p1. i. isolation and partial characterization. | despite the extensive genetic analysis of bacteriophage p1, the region of the viral genome that is responsible for its lytic (vegetative) replication has not been identified. in this paper we describe the identification of various fragments of p1 dna that can replicate an otherwise replication-defective lambda vector when they are cloned into that vector. the fragments share a 2800 base-pair segment of the p1 genome that is located adjacent to the immi region of the phage. replication mediated b ... | 1989 | 2738927 |
| genetic analysis of myxococcus xanthus and isolation of gene replacements after transduction under conditions of limited homology. | genetic analysis of myxococcus xanthus is greatly facilitated by the ability to introduce cloned dna into m. xanthus to generate gene replacement and merodiploid strains. however, gene replacement strains are difficult to obtain when the region(s) of homology between the cloned dna and the m. xanthus chromosome is limited (less than 1 kilobase). we found that gene replacements can be obtained at an increased frequency by a two-step procedure involving the use of bacteriophage p1 to isolate merod ... | 1986 | 3090023 |
| the superimmunity gene sim of bacteriophage p1 causes superinfection exclusion. | previous work has shown that the sim gene of bacteriophage p1, if cloned into a multicopy vector, confers immunity against p1 infection to cells. we show that a 1.85-kb dna fragment from the sim region of p1 (in the multicopy plasmid pmk4) expresses immunity and encodes three proteins with molecular weights of about 25, 24, and 15 kda. deletion of 650 bp from the sim region abolished synthesis of all three proteins and of the sim phenotype. expression of sim did not prevent adsorption of p1 to c ... | 1989 | 2763457 |
| bacteriophage p1 tail-fibre and dar operons are expressed from homologous phage-specific late promoter sequences. | two plasmid systems, containing the easily assayable galk and lacz functions, were employed to study the regulation of the bacteriophage p1 tail-fibre and dar operons. various p1 dna fragments carrying either the 5' end of lyda (the 1st gene in the dar operon) or the tail-fibre gene 19 precede the promoterless coding region of galk or were fused, in-frame, to the lacz gene. in the presence of an induced p1 prophage, galk and lacz activities were both detected after a 20 to 30 minute lag period, ... | 1989 | 2810357 |
| processing of the bacteriophage p1 packaging site (pac) is regulated by adenine methylation. | | 1988 | 3248724 |
| isolation and characterization of intermediates in site-specific recombination. | cre, the site-specific recombinase from bacteriophage p1, catalyzes a recombination reaction between specific dna sequences designated as lox sites. the breakage and rejoining of partners during this recombination process must be highly concerted because it has not been possible to detect intermediates of the reaction with wild-type cre. several mutant cre proteins have been isolated that produce significant amounts of a possible intermediate product of the recombination reaction. the product ha ... | 1987 | 2821547 |
| p1 plasmid replication requires methylated dna. | plasmids driven by the plasmid replication origin of bacteriophage p1 cannot be established in escherichia coli strains that are defective for the dna adenine methylase (dam). using a composite plasmid that has two origins, we show that the p1 origin cannot function even in a plasmid that is already established in a dam strain. an in vitro replication system for the p1 origin was developed that uses as a substrate m13 replicative-form dna containing the minimal p1 origin. the reaction mixture co ... | 1987 | 2826133 |
| uncoupling of the recombination and topoisomerase activities of the gamma delta resolvase by a mutation at the crossover point. | in several well-characterized site-specific recombination systems it has been shown that, for efficient recombination, the two recombining sites must have identical dna sequences across the region between the staggered points of exchange. the precise dna sequence of this overlap region, however, appears to be of little importance (with the exception of one position in the loxp site of bacteriophage p1 (ref. 6]. in this report we characterize a mutant recombination site for the site-specific reco ... | 1988 | 2833710 |
| multiple repressor binding sites in the genome of bacteriophage p1. | after digestion of bacteriophage p1 dna with ecori in the presence of p1 repressor, 6 repressor binding sites were identified in 5 of 26 ecori fragments. binding sites were localized by the decreased mobility of dna fragment-repressor complexes during electrophoresis and by dnase protection ("footprinting") analysis. the repressor binding sites, or operators, comprise a 17-base-pair-long consensus sequence lacking symmetrical elements. three operators can be related to known genes, whereas the f ... | 1987 | 3039493 |
| transduction of escherichia coli in soil. | bacteriophage p1-mediated generalized transduction of escherichia coli k-12 was assessed in nonsterile soil. auxotrophic recipient cells (thr- leu- thi- rpsl) were incubated in a sandy and a silty clay loam soil, and the transducing phage lysates from prototrophic strains carrying transposon 10(tn10) in either pure or arol regions were added. at intervals, the bacterial populations derived from the soils were plated on selective-differential media to enumerate prototrophic (thr+, leu+, or tcr) t ... | 1988 | 3042116 |
| participation of escherichia coli integration host factor in the p1 plasmid partition system. | stable maintenance of the plasmid prophage of bacteriophage p1 requires the p1 parb protein, which acts on a dna site termed pars. fractionation of extracts from escherichia coli cells overproducing parb revealed that a host factor, in addition to parb, is required to observe maximal binding to pars, as detected by a nitrocellulose filter retention assay. two observations indicated that this factor is e. coli integration host factor (ihf): purified ihf substituted specifically for host factor fr ... | 1988 | 2842786 |
| requirement of the escherichia coli dnaa gene function for integrative suppression of dnaa mutations by plasmid r 100-1. | the phenotype of escherichia coli dnaa missense and nonsense mutations was integratively suppressed by plasmid r100-1. the suppressed strains, however, could not survive when the dnaa function was totally inactivated. this was demonstrated by the inability of replacing the dnaa allele in the suppressed strain by a dnaa::tn10 insertion using phage p1-mediated transduction. when the intact dnaa+ allele was additionally supplied by a specialized transducing phage, lambda imm21 dnaa+, which integrat ... | 1988 | 2851703 |
| control of cell division by sex factor f in escherichia coli. iii. participation of the groes (mopb) gene of the host bacteria. | cell division of f+ bacteria is coupled to dna replication of the f plasmid. two plasmid coded genes, leta (ccda) and letd (ccdb) are indispensable for this coupling. to investigate bacterial genes that participate in this coupling, we attempted to identify the target of the division inhibitor (the letd gene product) of the f plasmid. two temperature-sensitive growth defective mutants were screened from bacterial mutants that escaped the letd product growth inhibition that occurs in hosts carryi ... | 1988 | 2901493 |
| transduction of escherichia coli by bacteriophage p1 in soil. | transduction of escherichia coli w3110(r702) and j53(rp4) (10(4) to 10(5) cfu/g of soil) by lysates of temperature-sensitive specialized transducing derivatives of bacteriophage p1 (10(4) to 10(5) pfu/g of soil) (p1 cm cts, containing the resistance gene for chloramphenicol, or p1 cm cts::tn501, containing the resistance genes for chloramphenicol and mercury [hg]) occurred in soil amended with montmorillonite or kaolinite and adjusted to a -33-kpa water tension. in nonsterile soil, survival of i ... | 1988 | 3046491 |
| altered phage p1 attachment to strains of escherichia coli carrying the plasmid colv,i-k94. | phages p1vir and p1cmclrf100 failed to form plaques on or multiply in escherichia coli strains carrying the colv,i-k94 plasmid; with p1cmclr100, the effect occurred both with phage from the lytic cycle and with that induced from a lysogen. the effect was on attachment, these p1 phages attaching poorly to colv,i-k94+ strains. this receptor defect appeared to result mainly from the presence of colv-encoded transfer and colicin components in the cells carrying colv,i-k94 and it was specific to this ... | 1987 | 2955078 |
| genetic suppression of a temperature-sensitive groes mutation by an altered subunit of rna polymerase of escherichia coli k-12. | temperature-resistant suppressor mutants were isolated from escherichia coli mutant strain groes131(ts). phage p1-mediated transduction and a two-dimensional gel electrophoretic analysis of cellular proteins indicated that these suppressor mutants carry an additional mutation in either the groel gene or the rpoa gene. | 1987 | 3546264 |
| d-arabinose metabolism in escherichia coli b: induction and cotransductional mapping of the l-fucose-d-arabinose pathway enzymes. | d-arabinose is degraded by escherichia coli b via some of the l-fucose pathway enzymes and a d-ribulokinase which is distinct from the l-fuculokinase of the l-fucose pathway. we found that l-fucose and d-arabinose acted as the apparent inducers of the enzymes needed for their degradation. these enzymes, including d-ribulokinase, appeared to be coordinately regulated, and mutants which constitutively synthesized the l-fucose enzymes also constitutively synthesized d-ribulokinase. in contrast to d ... | 1988 | 3056899 |