Publications

processing of the bacteriophage p1 packaging site (pac) is regulated by adenine methylation.		1988	3248724
properties of a mutant cre protein that alters the topological linkage of recombination products.	the bacteriophage p1 cre-loxp site-specific recombination system consists of two components: the cre recombinase protein and the loxp dna sequence where recombination takes place. we report here on the analysis of a mutation in the cre structural gene that produces a mutant protein with altered recombination properties. the mutant protein, cre111, carries out recombination at a much slower rate than the wild-type cre protein. to determine why the reaction is slow, we have examined a number of ac ...	1988	3262765
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
the immc region of phage p1 codes for a gene whose product promotes lytic growth.	the immc region of the temperate bacteriophage p1 contains c1, a gene that codes for a repressor of lytic growth. located in the region upstream of c1 are four open reading frames capable of coding for low-molecular-weight proteins. the efficiency of lysogeny by p1+cm was found to be reduced by almost 10(5)-fold when the host cells carry this region of immc on a multicopy plasmid. the sequences responsible for interfering with lysogen formation were localized to one of the small open reading fra ...	1990	2120849
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
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
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
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
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
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
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
[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
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
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
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 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
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
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
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
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
site-specific recombinase genes in three shigella subgroups and nucleotide sequences of a pinb gene and an invertible b segment from shigella boydii.	inversional switching systems in procaryotes are composed of an invertible dna segment and a site-specific recombinase gene adjacent to or contained in the segment. four related but functionally distinct systems have previously been characterized in detail: the salmonella typhimurium h segment-hin gene (h-hin), phage mu g-gin, phage p1 c-cin, and escherichia coli e14 p-pin. in this article we report the isolation and characterization of three new recombinase genes: pinb, pind, and defective pinf ...	1991	2061288
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
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
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
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
exchange of gene activity in transgenic plants catalyzed by the cre-lox site-specific recombination system.	the cre-lox site-specific recombination system of bacteriophage p1 was used to excise a firefly luciferase (luc) gene which had previously been incorporated into the tobacco genome. the excision event was due to site-specific dna recombination between two lox sequences flanking the luc gene and was catalyzed by the cre recombinase introduced by cross-fertilization. recombination resulted in the fusion of a promoter with a distally located hygromycin phosphotransferase (hpt) coding sequence and t ...	1992	1310059
a phage t4 in vitro packaging system for cloning long dna molecules.	recombinant plasmid dnas containing long dna inserts that can be propagated in escherichia coli would be useful in the analysis of complex genomes. we tested a bacteriophage t4 in vitro dna packaging system that has the capacity to package about 170 kb of dna into its capsid for cloning long dna fragments. we first asked whether the t4 in vitro system can package foreign dna such as concatemerized lambda imm434 dna and phage p1-pbr322 hybrid dna. the data suggest that the t4 system can package f ...	1992	1314208
control of segregation of chromosomal dna by sex factor f in escherichia coli. mutants of dna gyrase subunit a suppress letd (ccdb) product growth inhibition.	the leta (ccda) and letd (ccdb) genes, located just outside the sequence essential for replication of the f plasmid, apparently contribute to stable maintenance of the plasmid. the letd gene product acts to inhibit partitioning of chromosomal dna and cell division of the host bacteria, whereas the leta gene product acts to suppress the activity of the letd gene product. to identify the target of the letd gene product, temperature-sensitive growth-defective mutants were screened from bacterial mu ...	1992	1316444
cre-lox recombination in escherichia coli cells. mechanistic differences from the in vitro reaction.	the mechanism of the cre recombinase of bacteriophage p1 in escherichia coli cells was analyzed by topological methods in order to determine the important features of the in vivo reaction. lambda infection was used to introduce the cre gene into cells containing plasmid substrates. the products of cre resolution on substrates with directly repeated sites were predominantly free circles, even though decatenation by dna gyrase was blocked by the drug norfloxacin. recombination by cre was greatly s ...	1992	1324323
using bacteriophage p1 system to clone high molecular weight genomic dna.		1992	1336104
genetic characterization of the mechanism by which certain strains of escherichia coli survive in high kanamycin concentrations.	by genetic studies, it was tried to find the mechanism by which a bacterial fraction from different isolated clinical cultures resistant to 25 micrograms/ml of kanamycin can grow in media containing 500 micrograms/ml of kanamycin (at a frequency of about 10(-5)). this study was done in six clinical isolates of escherichia coli resistant to more than three antibiotics. the results from the bacterial fraction (subpopulation) resistant to high concentrations of kanamycin in the level of resistance ...	1992	1345305
cloning high molecular weight dna fragments by the bacteriophage p1 system.	the cloning of high molecular weight genomic dna promises to provide the means of mapping chromosomes, isolating genes, and understanding long-range effects on gene expression. this review describes the background and some recent advances in cloning of high molecular weight dna using the bacteriophage p1 system.	1992	1369729
toxic effects of high levels of ppgpp in escherichia coli are relieved by rpob mutations.	a controversy has surrounded the questions of whether or not guanosine tetraphosphate (ppgpp) is a specific inhibitor of bacterial rrna and trna synthesis, especially during normal exponential growth, and whether the rna polymerase is the target of ppgpp action. to answer these questions, a pbr322-derived plasmid, pkt28, was constructed that carries the escherichia coli rela gene encoding a ppgpp synthetase under control of the lacuv5 promoter. the plasmid was used to transform the ppgpp reporte ...	1992	1370817
bacteriophage p1 gene 10 is expressed from a promoter-operator sequence controlled by c1 and bof proteins.	gene 10 of bacteriophage p1 encodes a regulatory function required for the activation of p1 late promoter sequences. in this report cis and trans regulatory functions involved in the transcriptional control of gene 10 are identified. plasmid-borne fusions of gene 10 to the indicator gene lacz were constructed to monitor expression from the gene 10 promoter. production of gp10-lacz fusion protein became measurable at about 15 min after prophage induction, whereas no expression was observed during ...	1992	1400162
stoichiometry of the cre recombinase bound to the lox recombining site.	the site-specific recombinase cre from bacteriophage p1 binds and carries out recombination at a 34 bp lox site. the lox site consists of two 13 bp inverted repeats, separated by an 8 bp spacer region. both the palindromic nature of the site and the results of footprinting and band shift experiments suggest that a minimum of two cre molecules bind to a lox site. we report here experiments that demonstrate the absolute stoichiometry of the cre-lox complex to be one molecule of cre bound per inver ...	1992	1408747
a mouse genomic library in the bacteriophage p1 cloning system: organization and characterization.	using the bacteriophage p1 cloning system, we have constructed a two to three times coverage, high-molecular-weight (hmw) genomic library from mouse c127 fibroblast cells. the library consists of about 127,500 clones with an average insert size of about 70 kb that are organized into 300 primary pools containing approximately 425 clones per pool. for screening purposes the primary pools are combined into secondary pools (approximately 4250 clones each) and tertiary pools (approximately 21,250 clo ...	1992	1421762
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
design of a novel system for the construction of vectors for agrobacterium-mediated plant transformation.	the loxp-cre site-specific recombination system of phage p1 was used to develop a novel strategy to construct cointegrate vectors for agrobacterium-mediated plant transformation. a pti disarmed helper plasmid (pal1166) was constructed by replacing the oncogenic t-dna by a loxp sequence and a spectinomycin resistance marker in the octopine-type ptib6 plasmid. the cre gene was cloned into an unstable incp plasmid. a third plasmid, which did not replicate in agrobacterium and contained another loxp ...	1992	1494341
tissue- and site-specific dna recombination in transgenic mice.	we have developed a method of specifically modifying the mammalian genome in vivo. this procedure comprises heritable tissue-specific and site-specific dna recombination as a function of recombinase expression in transgenic mice. transgenes encoding the bacteriophage p1 cre recombinase and the loxp-flanked beta-galactosidase gene were used to generate transgenic mice. genomic dna from doubly transgenic mice exhibited tissue-specific dna recombination as a result of cre expression. further charac ...	1992	1495975
dna inversion regions min of plasmid p15b and cin of bacteriophage p1: evolution of bacteriophage tail fiber genes.	plasmid p15b and the genome of bacteriophage p1 are closely related, but their site-specific dna inversion systems, min and cin, respectively, do not have strict structural homology. rather, the complex min system represents a substitution of a cin-like system into an ancestral p15b genome. the substituting sequences of both the min recombinase gene and the multiple invertible dna segments of p15b are, respectively, homologous to the pin recombinase gene and to part of the invertible dna of the ...	1992	1534556
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
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
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
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
purification of the c1 repressor of bacteriophage p1 by fast protein liquid chromatography.	a fast protein liquid chromatographic method is described for the purification of the c1 repressor of bacteriophage p1 and its truncated form c1*. by using one crude extract, both repressor proteins were purified in parallel to homogeneity and were shown to interact specifically with p1 operator dna in vitro. the method involves an affinity chromatographic step on heparin-sepharose, followed by a combination of ion-exchange chromatography on q sepharose and s sepharose. the availability of a hom ...	1992	12126108
the antirepressor of phage p1. isolation and interaction with the c1 repressor of p1 and p7.	two antirepressor proteins, ant1 and ant2, of molecular weight 42 and 32 kda, respectively, are encoded by p1 as a single open reading frame, with the smaller protein initiating at an in-frame start codon. another open reading frame, icd, 5' upstream of and overlapping ant1 is required for ant1 expression. using appropriate ant gene-carrying plasmids we have overproduced and purified ant1/2 in the form of a protein complex and ant2 as a single protein. sequence analysis confirmed the n-terminal ...	1993	8224242
plasmid pbrint: a vector for chromosomal insertion of cloned dna.	plasmid pbrint is a pbr322 derivative [bolivar et al., gene 2 (1977) 95-113; balbás et al., gene 50 (1986) 3-40] that allows the insertion and replacement of dna sequences into the escherichia coli chromosome by homologous recombination. this method uses the inability of e. coli strain atcc47002 (jc7623) to replicate covalently closed circular (ccc) pbr322-derived plasmids, and the convenience of xgal+iptg screening for recombinants. the vector also contains suitable selection markers (ap and cm ...	1993	8294004
disruption of targeted gene in bacterial chromosome by using a temperature-sensitive plasmid.	the temperature-sensitive plasmid, psak3, was used in tryptophan-producing strains for tryptophanase gene disruption to block the degradation of tryptophan. plasmid psak3, which consisted of the psc103 plasmid containing a tetracycline resistant gene and a disrupted tryptophanase gene inserted by a kanamycin resistant gene, was integrated into the homologous site on the chromosome by gene recombination. through raising the temperature of cultivation to 42 degrees c and double antibiotics screeni ...	1993	8333867
[biological safety investigations of the production of human insulin by genetically-engineered e. coli k-12 cells. 3. plasmid transfer by natural transformation and transduction].	the transfer of the expression plasmid of human insulin psw3 by natural transformation and by transduction with phage p1 was investigated in laboratory media and in surface water samples. whereas pseudomonas stutzeri could be transformed by shuttle vectors which could replicate in this microorganism, no transformants were found with the insulin expression vector. e. coli k-12 could be transduced by phage p1vir only with chromosomal markers, not with plasmid dna. as the production strain w3110iqm ...	1993	8338615
amplification of the ends of dna fragments cloned in bacteriophage p1.		1993	8373578
mutants of escherichia coli with increased fidelity of dna replication.	to improve our understanding of the role of dna replication fidelity in mutagenesis, we undertook a search for escherichia coli antimutator strains with increased fidelity of dna replication. the region between 4 and 5 min of the e. coli chromosome was mutagenized using localized mutagenesis mediated by bacteriophage p1. this region contains the dnae and dnaq genes, which encode, respectively, the dna polymerase (alpha subunit) and 3' exonucleolytic proofreading activity (epsilon subunit) of dna ...	1993	8375645
plasmid addiction genes of bacteriophage p1: doc, which causes cell death on curing of prophage, and phd, which prevents host death when prophage is retained.	p1 lysogens of escherichia coli carry the prophage as a stable low copy number plasmid. the frequency with which viable cells cured of prophage are produced is about 10(-5) per cell per generation. here we show that a significant part of this remarkable stability can be attributed to a plasmid-encoded mechanism that causes death of cells that have lost p1. in other words, the lysogenic cells appear to be addicted to the presence of the prophage. the plasmid withdrawal response depends on a gene ...	1993	8411153
precise deletions in large bacterial genomes by vector-mediated excision (vex). the trfa gene of promiscuous plasmid rk2 is essential for replication in several gram-negative hosts.	we have developed a simple and efficient method of vector-mediated excision (vex) for in vivo generation of precisely defined deletions in large bacterial genomes. the system uses homologous recombination with small cloned fragments on specialized pvex plasmids to insert directly repeated bacteriophage p1 loxp sites at positions flanking the region to be deleted. in the presence of cre recombinase, the loxp sites are efficiently recombined to produce the deletion. deletion endpoints can be direc ...	1993	8450534
turbo cloning: a fast, efficient method for cloning pcr products and other blunt-ended dna fragments into plasmids.	the method uses a novel plasmid vector, p9lox5, containing a site-specific recombination sequence lox from the lox/cre recombinase system of bacteriophage p1. there are two distinct stages. firstly, vector and fragment dnas are ligated intermolecularly under conditions of macromolecular crowding (15% polyethylene glycol 6000) which accelerate blunt-end joining a thousandfold. secondly, circular recombinant molecules are efficiently excised from the ligation products by cre recombinase acting on ...	1993	8451184
a combined molecular and cytogenetic approach to genome evolution in drosophila using large-fragment dna cloning.	methods of genome analysis, including the cloning and manipulation of large fragments of dna, have opened new strategies for uniting molecular evolutionary genetics with chromosome evolution. we have begun the development of a physical map of the genome of drosophila virilis based on large dna fragments cloned in bacteriophage p1. a library of 10,080 p1 clones with average insert sizes of 65.8 kb, containing approximately 3.7 copies of the haploid genome of d. virilis, has been constructed and c ...	1993	8486077
cloning, expression, and characterization of the icd gene in the immi operon of bacteriophage p1.	the immi operon of p1 contains the genes c4, icd (formerly called orfx), and ant which are constitutively transcribed in that order from a single promoter, p51b. c4 is an antisense rna which is processed from the precursor transcript. c4 rna acts as a translational repressor of icd, thereby also inhibiting antirepressor (ant) synthesis. we have cloned the icd and the overlapping icd and ant genes. we show, by means of plasmid deletion analysis, that icd is translationally coupled to ant. an inte ...	1993	8491703
conformation of the origin of p1 plasmid replication. initiator protein induced wrapping and intrinsic unstacking.	the origin of plasmid dna replication in bacteriophage p1 has five 19 base-pair sites that bind the plasmid-encoded initiator, repa. here we show, using a dna band retardation assay, that repa can bend dna that carries one or more of the repa binding sites. repa binding to supercoiled dna carrying the five sites, directly repeated and phased two turns of b-dna apart, absorbs about one positive superhelical turn of dna as determined by two-dimensional gel electrophoresis. this indicates that the ...	1993	8496963