Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| action of an rna site at a distance: role of the nut genetic signal in transcription antitermination by phage-lambda n gene product. | the n gene product of escherichia coli phage lambda is a transcriptional activator that captures the host rna polymerase and modifies it to a termination-resistant form, permitting gene expression in two large polycistronic operons of the phage genome. antitermination in vitro requires at least one host factor called nusa, which directly binds the n protein as well as rna polymerase, and also a transcribed cis-acting site known as nut, within which lies the hypothesized n-recognition signal, box ... | 1990 | 2151659 |
| the use of transgenic mice for short-term, in vivo mutagenicity testing. | in order to develop a short-term, in vivo assay to study the mutagenic effects of chemical exposure, transgenic mice were generated using a lambda shuttle vector containing a lacz target gene. following exposure to mutagens, this target can be rescued efficiently from genomic dna prepared from tissues of the treated mice using restriction minus, in vitro lambda phage packaging extract and restriction minus escherichia coli plating cultures. mutations in the target gene appear as colorless plaque ... | 1990 | 2151115 |
| transcription-dependent competition for a host factor: the function and optimal sequence of the phage lambda boxa transcription antitermination signal. | ordered development of lambdoid phages relies on systems of transcription termination and antitermination. the phage-encoded n early regulatory proteins, acting with the nus proteins of escherichia coli, modify rna polymerase to a form that overrides many transcription termination signals. these modifications require cis-acting sites, nut, located downstream of the early phage promoters. the nut sites in phages lambda, 21, and p22, which share similarities but are not identical, contain two sign ... | 1990 | 2148536 |
| a short dna sequence from lambda phage inhibits protein synthesis in escherichia coli rap. | the escherichia coli rap mutant inhibits vegetative growth of bacteriophage lambda. phage mutations termed bar, which overcome the rap defect, have been mapped to three genetic loci in the pl operon. plasmids with a lambda wild-type bar dna segment cloned downstream from an active promoter cannot be maintained in rap mutant bacteria. the viability of a rap mutant strain decreases rapidly after induction of transcription through bar regions present on plasmids. under these (restrictive) condition ... | 1990 | 2147720 |
| lysis protein s of phage lambda functions in saccharomyces cerevisiae. | the lambda s lysis gene was cloned into a saccharomyces cerevisiae expression vector under gal1 control. induction with galactose in s. cerevisiae terminated cell growth and prevented colony formation. several membrane proteins immunoreactive with anti-s antibody accumulated in the membranes, indicating that sodium dodecyl sulfate-resistant oligomers of s are formed, similar to those observed in the membranes of escherichia coli cells killed by expression of the s gene. these observations sugges ... | 1990 | 2147680 |
| stimulation of mutations suppressing the loss of replication control by small alcohols. | transient exposure of lysogenic escherichia coli cells to small alcohols stimulated the frequency of mutations suppressing the lethal loss of replication control from a prophage fragment of bacteriophage lambda. the stimulation in mutation frequency paralleled the effect of mutagenic agents, and in this sense the alcohols behaved as mutagens. 10-min treatments above distinct threshold concentrations at 23%, 18%, 10% and 4% (v/v) were required in order for methanol, ethanol, isopropanol and propa ... | 1990 | 2143557 |
| a minor arginine trna mutant limits translation preferentially of a protein dependent on the cognate codon. | the escherichia coli argu gene encodes a rare arginine trna (anticodon ucu) that translates the similarly rare aga codon. the argu10(ts) mutation is a transition that changes the first nucleotide of the mature trna from g to a, presumably destabilizing the acceptor stem. this mutation, when present in haploid condition in the chromosome, reduces the growth rate at 30 degrees c and results in cessation of growth after 60 to 90 min at 43 degrees c. the mutation also preferentially limits (compared ... | 1990 | 2139647 |
| integration of bacteriophage lambda into the cryptic lambdoid prophages of escherichia coli. | bacteriophage lambda missing its chromosomal attachment site will integrate into reca+ escherichia coli k-12 and c at the sites of cryptic prophages. the specific regions in which these recombination events occur were identified in both lambda and the bacterial chromosomes. a noti restriction site on the prophage allowed its physical mapping. this allowed us to identify the locations of rac, qin, and qsr' cryptic prophages on the noti map of e. coli k-12 and, by analogy, to identify the cryptic ... | 1990 | 2139644 |
| celb, a gene coding for a bifunctional cellulase from the extreme thermophile "caldocellum saccharolyticum". | "caldocellum saccharolyticum" is an obligatory anaerobic thermophilic bacterium. a gene from this organism, designated celb, has been cloned in escherichia coli as part of a bacteriophage lambda gene library. this gene produces a thermostable cellulase that shows both endoglucanase and exoglucanase activities on test substrates and is able to degrade crystalline cellulose to glucose. the sequence of celb has homology with both exo- and endoglucanases described by others. it appears to have a cen ... | 1990 | 2126700 |
| bacterial expression of immunoglobulin vh proteins. | a bacterial expression system in escherichia coli has been developed that produces as much as 10 mg/l of culture of the vh protein associated with monoclonal antibodies specific for the 5-dimethylaminonaphthalene-2-sulfonyl (dns) group. this system has been applied to the expression of the vh genes derived from a low-affinity, igm-producing hybridoma and from a high-affinity, igg-producing cell line. the plasmid vectors (contributed by dr william f. studier) utilize a t7 expression cassette whos ... | 1990 | 2107393 |
| construction and characterization of a single-chain catalytic antibody. | the antigen-binding (fab) fragment of the catalytic monoclonal antibody npn43c9 has recently been cloned by using bacteriophage lambda. by inserting the variable regions of this fab coding sequence into a (nh2)-vl-linker-vh-(cooh) construct (where vl and vh represent the heavy and light chain variable regions), we have assembled a recombinant gene encoding a catalytic single-chain antigen-binding protein. this protein has been expressed in escherichia coli and exhibits the same catalytic paramet ... | 1991 | 2023948 |
| reca-independent resistance to irradiation with u.v. light in acid-habituated escherichia coli. | growth of escherichia coli 1829 colv, i-k94 at ph 5.0 led to an increase in u.v. resistance compared with cells grown at ph 7.0. this was due to a phenotypic change, since organisms grown at ph 7.0 showed increased resistance after only 2.5-5.0 min incubation at the mildly acid ph. other e. coli k12 derivatives became more u.v.-resistant at ph 5.0 including uvra, reca and pola1 mutants. organisms grown at ph 5.0 also showed increased weigle reactivation of u.v.-irradiated lambda phage and this a ... | 1991 | 2019551 |
| structural and functional comparison between the stability systems pard of plasmid r1 and ccd of plasmid f. | the stability determined by the systems pard of plasmid r1 and ccd of plasmid f is due to the concerted action of two proteins, a cytotoxin and an antagonist of this function. in this paper we report that ccda and kis proteins, the antagonists of the ccd and pard systems respectively, share significant sequence homologies at both ends. in kis, these regions seem to correspond to two different domains. despite the structural similarities, kis and ccda are not interchangeable. in addition we have ... | 1991 | 2017133 |
| characterization of the pilin gene of moraxella bovis dalton 2d and expression of pili from m. bovis in pseudomonas aeruginosa. | the pilin gene of moraxella bovis dalton 2d was isolated by cloning in pseudomonas aeruginosa. the nucleotide sequence of this gene encodes a prepilin of 156 amino acid residues. when high levels of pilin were expressed from the gene in p. aeruginosa, by using the pl promoter of bacteriophage lambda inserted upstream of the coding sequence, pili which were indistinguishable from pili of m. bovis were produced. | 1990 | 1971258 |
| a cdna encoding 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase from solanum tuberosum l. | a cdna encoding potato (solanum tuberosum l.) 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase, the first enzyme of the shikimate pathway, was cloned into phage lambda gt11. the clone represents the first cdna for this enzyme from any eukaryotic source. the nucleotide sequence of the cdna was determined, and its identity was confirmed through partial amino acid sequence analysis of the encoded enzyme. the cdna contains a 1527-base pair open reading frame that encodes a polypeptide with a cal ... | 1990 | 1967256 |
| cloning, sequencing and overexpression of the gene for prokaryotic factor ef-p involved in peptide bond synthesis. | a soluble protein ef-p (elongation factor p) from escherichia coli has been purified and shown to stimulate efficient translation and peptide-bond synthesis on native or reconstituted 70s ribosomes in vitro. based on the partial amino acid sequence of ef-p, 18- and 24-nucleotide dna probes were synthesized and used to screen lambda phage clones from the kohara gene bank. the entire ef-p gene was detected on lambda clone #650 which contains sequences from the 94 minute region of the e.coli genome ... | 1991 | 1956781 |
| rna polymerases from pseudomonas aeruginosa and pseudomonas syringae respond to escherichia coli activator proteins. | the activities of rna polymerases (rnaps) from pseudomonas aeruginosa and pseudomonas syringae were compared with that of escherichia coli rnap. all three enzymes are able to initiate transcription at the trpba promoter of p. aeruginosa and at the coliphage lambda promoters, prm and pre, in response to heterospecific activators (trpi protein, repressor, and cii protein, respectively). however, both pseudomonas polymerases have less stringent requirements for promoter recognition in the absence o ... | 1991 | 1898924 |
| bacteriophage lambda promoters pl and pr: sequence determinants of in vivo activity and of sensitivity to the dna gyrase inhibitor, coumermycin. | sequence encompassing the region between bp -43 and +8 of the pl and pr promoters of bacteriophage lambda, as well as sequence variants of these promoters, were compared with respect to their ability to drive a promoterless cat gene in vivo. for both pl- and pr-based promoters, variants with one nonconsensus bp rather than the consensus promoter were found to be maximally active. determination of promoter function in csh26 and c600 revealed a marked strain dependence in the activity of some prom ... | 1991 | 1847348 |
| selection of lacz operon fusions in genes of gluconate metabolism in e. coli. characterization of a gntt::lacz fusion. | the initial steps involved in the utilization of gluconate by e. coli, its incorporation into the cell and subsequent phosphorylation to gluconate 6-phosphate, conform two systems that duplicate activities. these systems, gnti and gntii, are specified by two sets of genes distinctly regulated and located respectively at the mala-asd (75 min) and fdp-vals (96 min) regions of the bacterial chromosome. the presence of duplicate activities in the metabolism of gluconate of e. coli, has made difficul ... | 1991 | 1843569 |
| recombinagenic processing of uv-light photoproducts in nonreplicating phage dna by the escherichia coli methyl-directed mismatch repair system. | nonreplicating lambda phage dna in homoimmune escherichia coli lysogens provides a useful model system for study of processes that activate dna for homologous recombination. we measured recombination by extracting phage dna from infected cells, using it to transfect reca recipient cells, and scoring the frequency of recombinant infective centers. with unirradiated phage, recombinant frequencies were less than 0.1%. however, recombination could be increased over 300-fold by prior uv irradiation o ... | 1991 | 1838344 |
| the kila operon of promiscuous plasmid rk2: the use of a transducing phage (lambda pklaa-1) to determine the effects of the lethal klaa gene on escherichia coli cells. | the kil-kor regulon of promiscuous plasmid rk2 includes the replication initiator gene trfa and several potentially host-lethal kil loci (kila, kilb, kilc, kile), whose functions may be involved in plasmid maintenance or broad host range. the kila locus consists of a single operon of three genes (klaa, klab, klac), each of which is lethal when expressed from the klaa promoter in the absence of repressors encoded by kora and korb. in this study, we examined the effects of the unregulated klaa gen ... | 1991 | 1838127 |
| [synthesis, secretion, and proteolytic degradation of diphtheria toxin in escherichia coli]. | the recombinant plasmids have been constructed encoding the synthesis of a full-sized diphtheria toxin from its own or pr, pl-promoters of bacteriophage lambda in escherichia coli cells. the high level constitutive synthesis of toxin results in slow cell growth and plasmid elimination. the toxin was mainly detected in the periplasm, partially in the membrane and to a less extent in the cytoplasm and culturing medium. the dimeric form of toxin was found in the cytoplasm. participation of toxin b- ... | 1991 | 1836836 |
| dna sequence changes in mutations induced by ultraviolet light in the gpt gene on the chromosome of escherichia coli uvr+ and urva cells. | sequence changes in mutations induced by ultraviolet light are reported for the chromosomal escherichia coli gpt gene in almost isogenic e. coli uvr+ and excision-deficient uvra cells. differences between the mutagenic spectra are ascribed to preferential removal of photoproducts in the transcribed strand by excision repair in uvr+ cells. this conclusion is confirmed by analysis of published results for genes in both uvr+ and uvr- cells, showing a similar selective removal of mutagenic products ... | 1991 | 1836051 |
| molecular cloning and nucleotide sequence of the rhizobium phaseoli reca gene. | a recombinant lambda phage carrying the reca gene of rhizobium phaseoli was isolated from a r. phaseoli genomic library by complementation of the fec- phenotype of the recombinant phage in escherichia coli. when expressed in e. coli, the cloned reca gene was shown to restore resistance to both uv irradiation and the dna alkylating agent methyl methanesulphonate (mms). the r. phaseoli reca gene also promoted homologous recombination in e. coli. the cloned reca gene was only weakly inducible in e. ... | 1991 | 1832737 |
| isolation and characterization of mutations in the bacteriophage lambda terminase genes. | the terminase enzyme of bacteriophage lambda is a hetero-oligomeric protein which catalyzes the site-specific endonucleolytic cleavage of lambda dna and its packaging into phage proheads; it is composed of the products of the lambda nul and a genes. we have developed a simple method to select mutations in the terminase genes carried on a high-copy-number plasmid, based on the ability of wild-type terminase to kill reca strains of escherichia coli. sixty-three different spontaneous mutations and ... | 1991 | 1830578 |
| the last duplex base-pair of the phage lambda chromosome. involvement in packaging, ejection and routing of lambda dna. | cosn is the site at which the bacteriophage lambda dna packaging enzyme, terminase, introduces staggered nicks to generate the cohesive ends of mature lambda chromosomes. genetic and molecular studies show that cosn is recognized specifically by terminase and that effects of cosn mutations on lambda dna packaging and cosn cleavage are well correlated. mutations affecting a particular base-pair of cosn are unusual in being lethal in spite of causing only a moderate defect in cosn cleavage and dna ... | 1991 | 1830344 |
| efficient excision of phage lambda from the escherichia coli chromosome requires the fis protein. | the escherichia coli protein fis has been shown to bind a single site in the recombination region of phage lambda and to stimulate excisive recombination in vitro (j. f. thompson, l. moitoso de vargas, c. koch, r. kahmann, and a. landy, cell 50:901-908, 1987). we demonstrate that mutant strains deficient in fis expression show dramatically reduced rates of lambda excision in vivo. phage yields after induction of a stable lysogen are reduced more than 200-fold in fis cells. the defect observed in ... | 1991 | 1829453 |
| heteroduplex chain polarity in recombination of phage lambda by the red, recbcd, recbc(d-) and recf pathways. | we have examined the chain polarity of heteroduplex dna in unreplicated, bacteriophage lambda splice recombinants when recombination was by the recbcd, recbc(d-), or recf pathway of escherichia coli or the red pathway of lambda. for each of these pathways, recombination is activated by the cutting of cos that accompanies chromosome packaging, and is effected by recombination enzymes acting at the right end created by that cutting. for exchanges occurring near cos, one parent makes a lesser physi ... | 1991 | 1829428 |
| dna recognition by the helix-turn-helix motif: investigation by laser raman spectroscopy of the phage lambda repressor and its interaction with operator sites ol1 and or3. | the lambda repressor provides a model system for biophysical studies of dna recognition by the helix-turn-helix motif. we describe laser raman studies of the lambda operator sites ol1 and or3 and their interaction with the dna-binding domain of lambda repressor (residues 1-102). raman spectra of the two dna sites exhibit significant differences attributable to interstrand purine-purine steps that differ in the two oligonucleotides. remarkably, the conformation of each operator is significantly a ... | 1991 | 1828373 |
| heat-inducible reactivation of uv-damaged bacteriophage lambda. | induction of the sos response in uv-irradiated bacteria leads to an increase in the survival of an infecting irradiated bacteriophage lambda (weigle 1953). we report that a similar reactivation of irradiated phage lambda was induced by shifting the culture of recipient bacteria from 30 degrees to 47 degrees c. however, this repair process was nonmutagenic. the amplitude of the phenomenon was increased with the quantity of uv lesions in the phage dna. it was present despite mutations affecting th ... | 1991 | 1827875 |
| identification of protein binding sites in genomic dna by two-dimensional gel electrophoresis. | we describe a simple two-dimensional electrophoresis procedure to identify the recognition sites of dna-binding proteins within large dna molecules. using this approach, we have mapped e. coli ihf (integration host factor) binding sites within phage lambda (48 kb) and phage mu (39 kb) dna. we are also able to visualize ihf binding sites in e. coli chromosomal dna (4,700 kb). we present an extension of this technique using direct amplification by pcr of the isolated restriction fragments, which s ... | 1991 | 1827523 |
| isolation and preliminary characterization of escherichia coli mutants resistant to lethal action of the bacteriophage lambda p gene. | both spontaneous and ntg-induced mutants of escherichia coli 594 insensitive to the lethal action of lambda p gene were isolated and called rpl (resistant to p lethality). these mutants were of two types, showing different phenotypes. on type i rpl mutants, lambda cl- and lambda v1v3 did not plate, while lambda vir, lambda cl- c17, lambda imm434, and lambda imm21 did; plasmid pmr45 carrying the lambda p gene could not complement lambda imm21p- phage in type i mutants. on the other hand, the type ... | 1991 | 1827225 |
| hu and integration host factor function as auxiliary proteins in cleavage of phage lambda cohesive ends by terminase. | hu and integration host factor (ihf) are small, basic heterodimeric dna-binding proteins which participate in transcription initiation, dna replication, and recombination. we constructed isogenic escherichia coli strains in which hu, ihf, or both proteins were absent. bacteriophage lambda did not grow in hosts lacking both hu and ihf. phage dna replication and late gene transcription were normal in the double mutants, but packaging of lambda dna was defective. mature phage dna molecules were abs ... | 1991 | 1825651 |
| saccharomyces cerevisiae elongation factor 2. genetic cloning, characterization of expression, and g-domain modeling. | the elongation factor 2 (ef-2) genes of the yeast saccharomyces cerevisiae have been cloned and characterized with the ultimate goal of gaining a better understanding of the mechanism and control of protein synthesis. two genes (eft1 and eft2) were isolated by screening a bacteriophage lambda yeast genomic dna library with an oligonucleotide probe complementary to the domain of ef-2 that contains diphthamide, the unique posttranslationally modified histidine that is specifically adp-ribosylated ... | 1992 | 1730643 |
| renaturation of cobra venom phospholipase a2 expressed from a synthetic gene in escherichia coli. | cobra venom (naja naja naja) phospholipase a2 (pla2) contains 14 cysteines in the form of 7 disulfide bonds amongst its 119 amino acids. a gene encoding the pla2 was synthesized and inserted into a bacterial expression vector containing the phage lambda pl promoter. in order to obtain protein without the initiating methionine at the n-terminus, a factor xa site was engineered upstream from the pla2 gene. upon heat-induction of the cells transformed with the expression plasmid, the protein is pro ... | 1992 | 1730025 |
| temperature-inducible gene expression in bacillus subtilis mediated by the ci857-encoded repressor of bacteriophage lambda. | an efficient system to control the expression of cloned genes in bacillus subtilis was established by introducing the escherichia coli bacteriophage lambda ci857 repressor-pr promoter system into this host. a staphylokinase reporter gene (sak42d), which was fused to the lambda pr promoter was constitutively expressed in b. subtilis even when the ci857 gene was present on the same plasmid. s1 nuclease mapping of the transcription start point confirmed that the pr promoter was active in b. subtili ... | 1990 | 1699846 |
| participation of rec genes of escherichia coli k 12 in w-reactivation of uv-irradiated phage lambda. | the effect of the recombinational deficiency on w-reactivation of uv-damaged phage lambda was explored. in this paper we show that w-reactivation is reduced by the recb21 and recf143 mutations after bleomycin (bm) and uv treatment. combination of these mutations in the recb21recf143 double mutant blocks w-reactivation completely after bm induction, but leaves residual w-reactivation ability after uv-irradiation, which is abolished by the introduction of uvrb deficiency (delta(uvrb-chla]. w-react ... | 1990 | 1689458 |
| immunoanalysis of ultraviolet radiation induced dna damage and repair within specific gene segments of plasmid dna. | the region-specific heterogeneity of repairing dna damage has been established in several biological systems. a flexible and sensitive approach, based upon dna damage specific antibodies, is described to monitor the repair of specific lesions within discrete genomic segments. membrane transblotted dna restriction fragments are immunoanalyzed for the initial formation and repair of 254 nm radiation induced pyrimidine dimers. sensitivity of dimer immunodetection increases proportional to fragment ... | 1991 | 1657185 |
| effect of rfah (sfrb) and temperature on expression of rfa genes of escherichia coli k-12. | in order to study the regulation of a large block of contiguous genes at the rfa locus of escherichia coli k-12 which are involved in synthesis and modification of the lipopolysaccharide core, the transposon tnlacz was used to generate in-frame lacz fusions to the coding regions of five genes (rfaq, -g, -p, -b and -j) within this block. the beta-galactosidase activity of strains in which these fusions had been crossed into the chromosomal rfa locus was significantly decreased when the rfah11 (sf ... | 1991 | 1655711 |
| a combination of rnase h (rnh) and recbcd or sbcb mutations in escherichia coli k12 adversely affects growth. | colony forming ability of escherichia coli strains carrying the rnh-339::cat mutant allele is strongly dependent on the recbcd and sbcb genes. a mutation inactivating either the recbcd nuclease or exonuclease i (sbcb) is sufficient to restrict severely the efficiency of plating of strains carrying the rnh-339::cat mutation. combining a non-lethal temperature-sensitive mutation in the recbcd nuclease, recb270 (ts) or recc271 (ts), with rnh-339::cat renders strains temperature sensitive for growth ... | 1991 | 1650908 |
| cyclic amp inhibits and putrescine represses expression of the spea gene encoding biosynthetic arginine decarboxylase in escherichia coli. | the spea gene of escherichia coli encodes biosynthetic arginine decarboxylase (adc), the first of two enzymes in a putrescine biosynthetic pathway. the activity of adc is negatively regulated by mechanisms requiring cyclic amp (camp) and camp receptor protein (crp) or putrescine. a 2.1-kb bamhi fragment containing the spea-metk intergenic region, spea promoter, and 1,389 bp of the 5' end of the spea coding sequence was used to construct transcriptional and translational spea-lacz fusion plasmids ... | 1991 | 1646785 |
| cloning and overexpression of the lactobacillus bulgaricus nad(+)-dependent d-lactate dehydrogenase gene in escherichia coli:purification and characterization of the recombinant enzyme. | the lactobacillus bulgaricus nad(+)-dependent d-lactate dehydrogenase gene was amplified by the polymerase chain reaction and cloned into an escherichia coli expression plasmid pkk223.3. attempts to clone the full-length chromosomal dna encoding d-lactate dehydrogenase from a partial sau3ai lambda phage library or an enriched clone bank in e. coli were unsuccessful. the recombinant plasmid pkbuldh containing the amplified gene overexpressed d-lactate dehydrogenase (greater than 30% of total solu ... | 1992 | 1610363 |
| cloning and nucleotide sequence of the escherichia coli cytidine deaminase (ccd) gene. | the structural gene that encodes cytidine deaminase (cdd) in escherichia coli was cloned from kohara phage lambda 365 (7f1), and its nucleotide sequence was determined. plasmids harboring the gene complemented chromosomal cdd mutations, enhanced cytidine deaminase activity in cell extracts, and directed the synthesis of a protein identical in mass and n-terminal amino acid sequence with cytidine deaminase purified from wild-type bacteria. metal analysis of the purified, plasmid-encoded deaminase ... | 1992 | 1567863 |
| t41 mutation in lac repressor is tyr282----asp. | a monomeric mutant of the lac repressor protein, designated t41, produced originally by the in vivo mutt mutagenesis exhibited behavior similar to mutants identified as tyr282----ser or tyr282----gln [schmitz et al., j. biol. chem. 251 (1976) 3359-3366]. the t41 gene, encoded within a phage lambda prophage in the escherichia coli genome, was amplified by polymerase chain reaction and sequenced. the only mutation found in the nucleotide sequence corresponded to position 282 in the protein, and th ... | 1992 | 1547952 |
| an efficient phage plaque screen for the random mutational analysis of the interaction of hiv-1 gp120 with human cd4. | a lambda phage expression methodology was adapted to dissect protein/ligand interactions efficiently through the creation and rapid screening of large numbers of mutants. here we describe the method and its specific application to the interaction between the external envelope glycoprotein of the human immunodeficiency virus (hiv-1), gp120, and the human cell surface protein cd4. random substitutions were introduced throughout the gp120 binding region (amino acids 38-62) in the amino-terminal dom ... | 1992 | 1533631 |
| lambda int protein bridges between higher order complexes at two distant chromosomal loci attl and attr. | the excisive recombination reaction of bacteriophage lambda involves a specific and efficient juxtaposition of two distant higher order protein-dna complexes on the chromosome of escherichia coli. these complexes, which mediate synapsis and strand exchange, consist of two dna sequences, attl and attr, the bivalent dna binding protein int, and the sequence-specific dna bending proteins, ihf, xis, and fis. the protein-protein and protein-dna interactions within, and between, these complexes were s ... | 1992 | 1533056 |
| effect of escherichia coli nusg function on lambda n-mediated transcription antitermination. | the escherichia coli nus factors act in conjunction with the bacteriophage lambda n protein to suppress transcription termination on the lambda chromosome. nusa binds both n and rna polymerase and may also interact with other nus factors. to search for additional components of the n antitermination system, we isolated host revertants that restored n activity in nusa1 mutants. one revertant, nusg4, was mapped to the rif region of the e. coli chromosome and shown to represent a point mutation near ... | 1992 | 1531224 |
| enriched sources of escherichia coli replication proteins. the dnag primase is a zinc metalloprotein. | primase, the product of the escherichia coli dnag gene, is the enzyme responsible for rna primer synthesis on both template strands at replication forks during chromosomal dna synthesis. the dnag gene was modified by replacement of the natural ribosome-binding site with one complementary to the 3' end of 16s rrna, and then inserted downstream of tandem bacteriophage lambda pr and pl promoters in the puc9-derived vector pce30. following thermal induction of transcription, the resulting plasmid pp ... | 1992 | 1511009 |
| involvement of the escherichia coli rna polymerase alpha subunit in transcriptional activation by the bacteriophage lambda ci and cii proteins. | escherichia coli cells harbouring the rpoa341 mutation produce an rna polymerase which transcribes inefficiently certain operons subject to positive control. here, we demonstrate that the rpoa341 allele also prevents lysogenization of the host strain by bacteriophage lambda, a process dependent upon the action of two phage-encoded activators. this phenomenon was shown to arise from an inability to establish an integrated prophage rather than a failure to maintain the lysogenic state. the inabili ... | 1992 | 1452017 |
| bacteriophage lambda papa: not the mother of all lambda phages. | the common laboratory strain of bacteriophage lambda--lambda wild type or lambda papa--carries a frameshift mutation relative to ur-lambda, the original isolate. the ur-lambda virions have thin, jointed tail fibers that are absent from lambda wild type. two novel proteins of ur-lambda constitute the fibers: the product of stf, the gene that is disrupted in lambda wild type by the frameshift mutation, and the product of gene tfa, a protein that is implicated in facilitating tail fiber assembly. r ... | 1992 | 1439823 |
| the translation initiation site of recombinant trypanosoma brucei ornithine decarboxylase varies with different promoters. | expression of the trypanosoma brucei ornithine decarboxylase (odc) gene in escherichia coli behind the lambda phage pr promoter led to the production of a recombinant enzyme having the same subunit molecular weight as the native enzyme [4]. however, when the same gene is expressed behind the tac promoter or the phoa promoter, the odcs produced by the transformed e. coli have subunit molecular weights approximately 2 kda higher than that of the native enzyme. amino terminal sequencing of the reco ... | 1992 | 1435879 |
| overproduction and purification of bacillus subtilis dna polymerase iii. | the objectives of this work were to engineer the cloned polc gene encoding bacillus subtilis dna polymerase iii for controlled overexpression in escherichia coli and to devise a facile purification scheme permitting the large-scale production of pure recombinant polymerase. the translational signals of polc were restructured by expression cassette pcr (macferrin et al., 1990, proc. natl. acad. sci. usa 87, 1937-1941), and the modified gene was inserted into the expression plasmid, pkc30 (rosenbe ... | 1992 | 1422209 |
| construction of coliphage lambda charon vectors with bamh1 cloning sites. 1980. | 1992 | 1422018 | |
| characterization of the transcription activator protein c1 of bacteriophage p22. | we cloned, expressed, and purified the positive regulatory protein c1 of the temperate phage p22 of salmonella typhimurium. the purified protein was characterized as to its amino acid composition, protein sequence, molecular weight, and antigenicity. p22 c1 was shown to be a tetrameric protein composed of four identical subunits with m(r) = 10,000. moreover, we identified and characterized two p22 c1-dependent phage promoters, p(re) and pa23, whose function was completely dependent on c1 both in ... | 1992 | 1385814 |
| both forms of translational initiation factor if2 (alpha and beta) are required for maximal growth of escherichia coli. evidence for two translational initiation codons for if2 beta. | the gene infb codes for two forms of translational initiation factor if2; if2 alpha (97,300 da) and if2 beta (79,700 da). if2 beta arises from an independent translational event on a gug codon located 471 bases downstream from if2 alpha start codon. by site-directed mutagenesis we constructed six different mutations of this gug codon. in all cases, if2 beta synthesis was variably affected by the mutations but not abolished. we show that the residual expression of if2 beta results from translatio ... | 1992 | 1374802 |
| spontaneous transposition in the bacteriophage lambda cro gene residing on a plasmid. | a new mutagenesis assay system based on the phage lambda cro repressor gene residing on a plasmid was developed. the assay detects mutations in cro that decrease the binding of the repressor to the or operator in an or pr-lacz fusion present in a lambda prophage. mutations arose spontaneously during growth of e. coli cells harboring cro plasmids at a frequency of 3-6 x 10(-6). analysis of some 200 cro mutants from several 'wild-type' strains revealed a substantial fraction of 25-70% insertion ev ... | 1992 | 1373849 |
| lambda vectors for stable cloned gene expression. | the bacteriophage lambda offers a unique opportunity concurrently to minimize segregational instability in recombinant systems by chromosomal integration of the cloned gene and to achieve high cloned gene expression during an abortive lytic phase. lysis leads approximately to a 100-fold amplification of the cloned gene. cell lysis in the lytic state is blocked by a specific mutation (sam), allowing the cell to maintain its integrity, and lambda dna packaging is blocked by other mutations (wam, e ... | 1990 | 1368559 |
| efficient large-scale sequencing of the escherichia coli genome: implementation of a transposon- and pcr-based strategy for the analysis of ordered lambda phage clones. | we have developed a strategy for efficient sequence analysis of the genome of e. coli k-12 using insertions of a tn5-derived mini-transposon into overlapping ordered lambda phage clones to provide universal primer-binding sites, and pcr amplification of dna segments adjacent to the insertions. transposon-containing clones were selected by blue plaque formation on a dnabamber laczamber e. coli strain. insertion points every 0.5-1 kb were identified by 'analytical pcr' and segments between the tra ... | 1992 | 1336178 |
| a selective lambda phage cloning vector with automatic excision of the insert in a plasmid. | a bacteriophage lambda cloning vehicle has been constructed for the generation of cdna libraries. the vector has the following properties. (1) it has a unique bamhi site engineered into the lambda gam gene. segments of dna can be cloned into this site and clones with an insert can be selected by their ability to grow on an escherichia coli host lysogenic for phage p2 (spi- phenotype). (2) when the recombinant phage infects a cre-producing e. coli strain, a site-specific recombination event resul ... | 1992 | 1327972 |
| the construction of streptomyces cyaneus genomic libraries in escherichia coli is dependent upon the use of mcr-deficient strains. | streptomyces cyaneus genomic dna ligated into either lambda phage or plasmid vectors was very inefficiently cloned into standard escherichia coli host strains. however, the same material could be efficiently cloned using mcr-deficient e. coli strains. these results suggest that the s. cyaneus genome contains 5-methylcytosine residues, some of which occur within the recognition sequences of the e. coli mcr restriction system. | 1992 | 1327960 |
| nonrandom orientation of transposon tn5supf insertions in phage lambda. | transposition of mini-transposon tn5supf to phage lambda can be selected in two ways: (i) by plaque formation on a dnab amber strain of escherichia coli, which requires expression of the transposon-borne suppressor trna gene (supf) during lytic phage growth, or (ii) by lysogenization of a strain with amber mutations in tet and amp resistance genes, and selection of tcr apr (sup+) transductant colonies. tn5supf insertions in several lambda clones were isolated and mapped using a polymerase chain ... | 1992 | 1316868 |
| alleviation of ecok dna restriction in escherichia coli and involvement of umudc activity. | the activity of the ecok dna restriction system of escherichia coli reduces both the plating efficiency of unmodified phage lambda and the transforming ability of unmodified pbr322 plasmid dna. however, restriction can be alleviated in wild-type cells, by uv irradiation and expression of the sos response, so that 10(3)- to 10(4)-fold increases in phage growth and fourfold increases in plasmid transformation occurred with unmodified dna. restriction alleviation was found to be a transient effect ... | 1992 | 1310522 |
| phage lambda has an analog of escherichia coli reco, recr and recf genes. | the recf pathway catalyzes generalized recombination in escherichia coli that is mutant for recbc, sbcb and sbcc. this pathway operating on conjugational recombination requires the reca, recf, recj, recn, reco, recq, recr, ruva, ruvb and ruvc genes. in contrast, lambda mutant for its own recombination genes, int, red alpha and red beta, requires only the reca and recj genes to recombine efficiently in recbc sbcb sbcc cells. deletion of an open reading frame in the ninr region of lambda results i ... | 1992 | 1310087 |
| differential sensitivity to antibiotics of trp mrna synthesis originating at the trp promoter and the lambda promoter. | transcription of the escherichia coli trp operon translocated into the early region of bacteriophage lambda can occur under the control of either of two promoters, the trp promoter on the lambda promoter (ol of n gene). (imamato, f. and tani, s. (1972) nat. new biol. 240, 172-175 and ihara s. and imamoto, f. (1976) biochim. biophys. acta 432, 199-211). trp mrna synthesis originating at the trp promoter stopped when translation was blocked by chloramphenicol tetracycline erythromycin or puromycin ... | 1976 | 1268253 |
| specific hydrolysis of the cohesive ends of bacteriophage lambda dna by three single strand-specific nucleases. | procedures have been worked out for aspergillus nuclease s1 and mung been nuclease to quantitatively cleave off both of the 12-nucleotide long, single-stranded cohesive ends of lambdadna. this cleavage is indicated by the almost complete elimination of the repair incorporation of radioactive nucleotides by dna polymerase into the digested dna. with s1 nuclease, cleavage was complete at 10 degrees as well as at 30 degrees. under the conditions for quantitative cleavage of the single-stranded regi ... | 1975 | 1141222 |
| genetic consequences of transfection with heterduplex bacteriophage lambda dna. | the role of rectification of heteroduplex heterozygotes in the formation of recombinant genotypes involving closely linked markers has been examined. heteroduplex molecules of bacteriophage lambda dna, heterozygous at several alleles, have been constructed and the genetic composition of phage present in infective centers derived by transfection with such molecules has been determined. allele loss and concomitant recombinant formation is frequent, and appears to reflect marker specificity as well ... | 1975 | 1107809 |
| reversible interaction between coliphage lambda and its receptor protein. | 1975 | 1107562 | |
| induction of error-prone repair as a consequence of dna ligase deficiency in escherichia coli. | dna ligase deficiency is shown to induce generalized mutator activity in e. coli. this mutator activity is unaffected by 3 mug/ml of chloramphenicol but is abolished both in lig-reca double mutants and by incubation with 20 mug/ml of chloramphenicol. dna ligase deficiency is also shown to reactivate ultraviolet light-irradiated phage lambda and t7 and to increase both spontaneous and ultraviolet light-induced mutagenesis in phage lambda, all of which are abolished in lig-reca strains. interactio ... | 1975 | 1105587 |
| phage lambda receptor chromosomes for dna fragments made with restriction endonuclease iii of haemophilus influenzae and restriction endonuclease i of escherichia coli. | 1975 | 1104875 | |
| bacteriophage lambda induction causes increased production of e. coli lysine transfer rna. | 1975 | 1103738 | |
| visualization of a novel junction in bacteriophage lambda dna. | at early times after infection of a reca derivative of escherichia coli with lambdab221c126red270a42 phage, a low but significant proportion of intracellular lambda molecules show a novel junction. these junctions are also present, although in reduced numbers, in a lysate obtained at late times after infection of a reca+ host with lambdaciiciii phage. fine structure and denaturation mapping analyses showed that these junctions occur at homologous positions and that they are compatible with the o ... | 1975 | 1103134 |
| studies on the cleavage of bacteriophage lambda dna with ecori restriction endonuclease. | 1975 | 1102702 | |
| processing of bacteriophage lambda dna during its assembly into heads. | 1975 | 1102699 | |
| synthesis and degradation of early mrna in lambda phage. | using two different escherichia coli mutants defective in elongation factors efg and efts required for peptide synthesis, lambda phage with or without a tof mutation was analysed for synthesis of early mrna by dna-rna hybridization technique. (1) in cp78g carrying temperature-sensitive elongation factor g, shift-up to high temperature (41 degrees c) in the middle of phage infection did not affect early mrna synthesis with lambdatof+ phage but did inhibit it with lambdatof- phage. (2) in hak88 ca ... | 1975 | 1101966 |
| constitutive integrative recombination by bacteriophage lambda. | 1975 | 1094679 | |
| mismatch repair in heteroduplex dna. | dna with base pair mismatches was prepared by annealing mixtures of genetically marked dna from bacteriophage lambda. this heteroduplex dna was used to transfect bacteria under conditions minimizing recombination. genetic analysis of the progeny phages indicates that: (i) mismatch repair occurs, usually giving rise to a dna molecule with one chain with the genotype arising from repair and one parental chain. (ii) the frequency of repair of a given mismatch to wild type depends on the marker, ran ... | 1975 | 1094458 |
| the biological activity of bacteriophage dna, prepared by the cationic detergent dilution technique. | the preparation of phage lambda dna infecting e. coli k 12 with cationic detergent is described. this dna infects e. coli spheroblasts with the same efficiency as dna prepared by phenol methods. | 1975 | 1093138 |
| electron microscope heteroduplex studies of sequence relations among bacterial plasmids: identification and mapping of the insertion sequences is1 and is2 in f and r plasmids. | heteroduplex experiments between the plasmid r6 and one strand of the deoxyribonucleic acid (dna) of a lambda phage carrying the insertion sequence is1 show that is1 occurs on r6 at the two previously mapped junctions of resistance transfer factor (rtf) dna with r-determinant dna. from previous heteroduplex experiments, it then follows that is1 occurs at the same junctions in r6-5, r100-1, and r1 plasmids. heteroduplex experiments with the dna from a lambda phage carrying the insertion sequence ... | 1975 | 1092668 |
| mutations simultaneously affecting endonuclease ii and exonuclease iii in escherichia coli. | we studied mutants of e. coli originally identified as being deficient in either endonuclease ii (deoxyribonucleate oligonucleotidohydrolase, ec 3.1.4.30) or exonuclease iii [deoxyribonucleate (double-stranded) 5'-nucleotidohydrolase, ec 3.1.4.27] activity. twelve independently derived mutants were tested, including three new endonuclease ii mutants. deficiency of one enzyme was always accompanied by deficiency of the other. furthermore, temperature-sensitivity of one activity was always accompa ... | 1975 | 1091930 |
| proteolytic cleavage of bacteriophage lambda repressor in induction. | the bacteriophage lambda repressor, a protein that maintains the lysogenic state of a bacterium containing a lambda prophage, is cleaved when the lysogen is induced by mitomycin c or ultraviolet light. this cleavage does not occur when induction is prevented by mutational alteration either of the phage repressor or of the host reca gene product. proteolytic cleavage may be the primary mechanism of repressor inactivation in this induction pathway, or it may follow a different event which causes t ... | 1975 | 1090931 |
| morphogenesis of the tail of bacteriophage lambda. ii. in vitro formation and properties of phage particles with extra long tails. | 1975 | 1089336 | |
| location in bacteriophage lamdba dna of cleavage sites of the site-specific endonuclease from bacillus amyloliquefaciens h. | the sites in escherichia coli bacteriophage lambda dna cleaved by the site-specific endonuclease isolated from bacillus amyloliquefaciens h (bami) are found to be at 0.114, 0.466, 0.580, 0.713, and 0.861 lambda units. the sites were located by analysis of the products of digestion of lambda dna and lambda-ara transducing phage dna, and verified by double digestion with bami and ecori. | 1976 | 1083914 |
| transposition of r factor genes to bacteriophage lambda. | transpositions of segments of r factor (antibiotic resistance plasmids) to bacteriophage lambda have been selected and characterized. cells of escherichia coli harboring r factors that determine kanamycin resistance were infected with phage lambda, and lambdakan transducing lines were obtained. each of the three examined is unusual when compared to lambda transducing phages containing e. coli chromosomal genes: the kan insertions (a) occur at several sites, each well removed from the integration ... | 1975 | 1059152 |
| [substrate of a uv-induced repair system providing for w-reactivation of lambda phage]. | escherichia coli uvra, pola and uvrd cells carrying non-uv-inducible prophage lambdac1857ind- were infected with 3h-thymidine labelled homoimmune phage lambdac1857, and the effect of uv-irradiation of super-infecting phage and lysogenic bacterial cells on the content of intracellular covalently-closed lambda dna circles (cccdna) and pyrimidine dimer content in lambda dna are studied. uv-irradiation of host cells results in two-fold increase of relative content of cccdna of uv-irradiated phage la ... | 1976 | 1001892 |
| [new mutations in the early stage of phage lambda]. | 1976 | 798250 | |
| physicochomecial studies on interactions between dna and rna polymerase. isolation and mapping of a t7 dna fragment containing the early promoters for escherichia coli rna polymerase. | the cleavage sites in the early promoter region of coliphage t7 have been mapped for four restriction enzymes. they are, from the left end in base pairs, 1100 and 740 for hinf; 680, 320, 530, 240, 77, and 67 for hind ii; 620 and 530 for hpa ii; 790 for alu i. the nucleotide sequence between the hind ii site at 680 base pairs from the left end and the hinf site at 740 base pairs from the left end has been determined, from which the start point of the promoter a3 is located at 720 base pairs from ... | 1976 | 795461 |
| suppressible mutations in the cro gene of bacteriophage lambda. | 1976 | 795138 | |
| the yield of radiation-induced dna single-strand breaks in escherichia coli and superinfecting phage lambda at different dose rates. repair of strand breaks in different buffers. | 1976 | 794917 | |
| induction of sigma factor synthesis in escherichia coli by the n gene product of bacteriophage lambda. | thermoinduction of cells of e. coli carrying prophage lambdaci857 within the bfe gene brings about not only "escape synthesis" of core subunits of the dna-dependent rna polymerase (rna nucleotidyltransferase, nucleosidetriphosphate:rna nucleotidyltransferase, ec 2-7-7-6), but also a striking stimulation of sigma factor synthesis. the latter phenomenon, termed sigma induction, is generally observed after lambda phage infection or prophage induction. a series of experiments with various bacterial ... | 1976 | 794877 |
| a transducing bacteriophage lambda carrying the structural gene for elongation factor ts. | a specialized transducing bacteriophage lambdadpolcdap d-9 has been isolated that carries the structural gene for ef-ts1 (tsf). the presence of ef-ts among the proteins synthesized under the direction of this phage in uvl-inactivated cells has been detected by two-dimensional gel electrophoresis and has been verified by antibody precipitation. in an induced lysogen of this phage the relative rate of synthesis of ef-ts is increased 4-fold. evidence is presented which suggest that the structural g ... | 1976 | 792684 |
| maturation of a single lambda phage particle from a dimeric circular lambda dna. | 1976 | 790755 | |
| specialized transduction of colicin e1 dna in escherichia coli k-12. | genetic studies were made on e. coli k-12 tm96, which carries recombinant molecules constructed by in vitro combination of colicin e1 dna and a dna fragment of e. coli for guanine synthesis derived from transducing phage. the recombinant molecules existed as stable plasmids within the cell and contained genes for colicin e1 immunity and the guaa enzyme (xanthosine 5'-monophosphate aminase) together with a part of the lambda genome, r through j: (r-a-f-j)+. a block of the lambda genome, int throu ... | 1976 | 787989 |
| role of the bacterial and phage recombination systems and of dna replication in genetic recombination of uv-irradiated phage lambda. | in this paper are studied in e. coli k12 the influence of the bacterial rec and phage mu red recombination systems on the rescue of the o plus gene from the prophage by a superinfecting o minus phage, uv irradiated or not. in the absence of uv irradiation the red system produces more recombinants than does the rec system, and its action requires dna replication. the presence of uv lesions in the mu dna facilitates the action of the rec system, which is more efficient in this instance than the re ... | 1976 | 785209 |
| lethal lysogenization by coliphage lambda. | 1976 | 782020 | |
| transposition and fusion of the lac genes to selected promoters in escherichia coli using bacteriophage lambda and mu. | 1976 | 781293 | |
| morphogenesis of bacteriophage lambda: electron microscopy of thin sections. | 1976 | 781268 | |
| isolation and properties of escherichia coli mutants which are nonpermissive for the growth of phage lambda. | by selecting survivors of lambda phage infection, mutants of escherichia coli k12 that block reproduction cycle of the phage have been isolated. fourteen of these phage-tolerant mutants (lam mutants) were chosen and characterized biochemically and genetically. it was shown that these mutants were tolerant to infection by all the lambdoid phages, except for few cases, but they were susceptible to infection by a non-lambdoid temperate phage (phi299), p1 or t phages. the mutants can be divided into ... | 1975 | 772257 |
| [competence in escherichia coli cells. iii. formation of competent states in escherichia coli x7026 and escherichia coli hfr h cells during storage in different conditions]. | the competence formation in 2 strains of escherichia coli x7026 and hfr h to isolated phage gamma dna after the prolonged treatment of cells with ca++ ions at low temperatures was investigated. in both strains studied the sensitivity of cells to phage lambda dna increased during several days of maintenance at 4 degrees c in 0.2 m cacl2, and reached the maximal value in 24-48 hours for e. coli hfr h cells, and in 72-96 hours for e. coli x7026 cells. cells maintained in cacl2 for 24 hours and more ... | 1975 | 767199 |
| recombination of bacteriophage phi x174 by the red function of bacteriophage lambda. | recombination of bacteriophage phi x174 was effectively promoted when the red function of lambda was supplied by either co-infection with lambda or induction of lambda lysogens. mutations in red alpha and red beta genes of lambda abolished recombination nearly completely, whereas a mutation in gam gene reduced it only slightly. the red-promoted recombination of phi x174 occurred in reca, recb, and pola mutants as well as in wild-type strains of escherichia coli. it was further stimulated when ph ... | 1979 | 430603 |
| coupling of lac mrna transcription to translation in escherichia coli cell extracts. | in an extract containing all the components for lac gene expression except washed ribosomes, lac mrna formation was increased 4- to 6-fold by the addition of washed ribosomes. the formation of beta-galactosidase mrna and enzyme showed very different dependency on added ribosomes. enzyme was formed in proportion to the number of ribosomes added, whereas 10% of the standard level of ribosomes promoted full levels of transcription. consistent with their action in vivo, chloramphenicol and erythromy ... | 1978 | 415305 |