Publications

the nucleotide sequence in the promoter region of the gene n in bacteriophage lambda.	the sequence of 18 nucleotides in the region preceding the initiation of transcription of the gene n of bacteriophage lambda has been determined to be as follows (see article). the basic approach used for the sequence determination involved escherichia coli dna polymerase i-catalyzed elongation of the octadecanucleotide primer, dt-c-a-g-t-g-c-g-t-c-c-t-g-c-t-g-a-ru, possessing the appropriate polarity and nucleotide sequence corresponding to the 5' end of the gene n transcript. following hybridi ...	1975	167018
pleiotropic effects of a dna adenine methylation mutation (dam-3) in escherichia coli k12.	the dam-3 mutation results in a five-fold reduction in the number of 6-methyl-adenine (6-mea) residues in the dna of e. coli k12 or phage lambda. the dna of phage fd appears to be devoid of 6-mea when propagated on dam-3 bacteria. the phenotypic differences between dam-3 and dam+ bacteria include: (i) increased free phage in lysogenic dam-3 cultures, (2) increased sensitivity to methyl methanesulfonate (mms), (3) inviability of dam-3 lex-i strains, (4) lower molecular weight of dna in dam-3 bact ...	1975	167279
the action of colicin e2 on supercoiled lambda dna.ii. experiments in vitro.	an in vitro system has been developed to test whether colicin e2 possesses dnase activity. purified colicin e2 preparations introduced one single-strand scission in supercoiled lambda phage dna. glycerol gradient fractionation of colicin e2 supports the association of in vitro action with in vivo cell-killing activity. colicin e2 preparations also attacked superhelical sv40 dna yielding open circles and fragments and single-stranded fd dna molecules causing one or more endonucleolytic breaks. th ...	1975	167801
operator-promoter functions in the threonine operon of escherichia coli.	the prophage curing properties of secondary-site lysogens of coliphage lambda have been studied. the site of integration in the original lysogen (l79) is within the ooerator-promoter region of the thr operon. as a result, expression of the thr enzymes is reduced, and the strain is a leaky threonine auxotroph. heat pulse curing of strain l79 and a thr+ lysogenic revertant (l79-20) showed that heat pulse curing of both lysogens was int and xis dependent and occurred by correct excisions of the pro ...	1975	170244
selective effects of mgcl2 and temperature on the initiation of transcription at lac, gal, and lambda promoters.	we have studied the effect of mg2+ on the formation of transcription preinitiation complexes (open complexes) at two adenosine 3':5'-monophosphate (cyclic amp)-cyclic amp receptor protein (crp)-dependent promoters (lac and gal) and two phage lambda promoters, pl and pr. mg2+ strongly interferes with open complex formation at the lac and gal promoters, partially inhibits the lambda pr promoter, and is without effect on the lambda pl promoter. mutations in the lac and gal promoters can affect the ...	1975	170282
[rna fragments rich in g and a nucleotides obligatory for in vitro dna replication of phages phi-x 174 and lambda].	evidence was presented that in vitro conversion of single-stranded dna of phage phi x 174 to the double-stranded replicative form by partially purified dna-dependent dna polymerase i requires a specific rna fragment acting as primer (25-50 nucleotides). rna fragments highly rich in nucleotides a and g were obtained by partial degradation of e. coli m 500 sho-r ribosomal rna with pancreatic ribonuclease. they become covalently bound to the newly synthesized dna chain of the replicative form of ph ...	1975	172251
properties of adenyl cyclase and cyclic adenosine 3',5'-monophosphate receptor protein-deficient mutants of escherichia coli.	several spontaneous cya and crp mutants of escherichia coli have been selected as clones simultaneously resistant to phage lambda and nalidixic acid and characterized. both cya and crp mutants have been found to grow as cocci with increased doubling times. they have increased resistance to some mutagens (methylmethanesulfonate, ultraviolet light, gamma rays), antibiotics (nalidixic acid, ampicillin), phages (lambda, t6), sublethal heat and hypotonic shock, and decreased resistance to neutral det ...	1976	173710
construction and propagation of a defective simian virus 40 genome bearing an operator from bacteriophage lambda.	a 2400 base pair dna segment containing the leftward operator (ol) of phage lambda was covalently joined in vitro to a fragment of simian virus 40 (sv40) dna harboring the sv40 replication origin. the recombinant molecule was propagated in the presence of helper wild-type sv40 dna in monkey kidney cells and partially cloned by an infectious center procedure. after propagation in monkey cells and purification, the hybrid dna could be distinguished from wild-type sv40 dna by its shortened length ( ...	1976	177971
multiple steps during the interaction between coliphage lambda and its receptor protein in vitro.		1976	180667
suppression of polarity of insertion mutations in the gal operon and n mutations in bacteriophage lambda.	bacterial mutations (psua and psu) known for their ability to suppress the polarity on nonsense mutations are shown to suppress the polarity of certain insertion mutations in the gal operon. the short insertion, is1 (800 nucleotide pairs), is about 15 to 50% suppressed, whereas longer insertions, is2 (1,400 nucleotide pairs), and is3 (1,200 nucleotide pairs), are not. some of the polarity suppressor mutations (psu-1, psu-2, and psu-3) are at least partially permissive for n-gene mutations (n7 an ...	1976	181361
the adsorption of coliphage lambda to its host: effect of variations in the surface density of receptor and in phage-receptor affinity.		1976	181582
the restriction endonucleases in bacillus amyloliquefaciens n strain. substrate specificities.	two species of restriction endonuclease were isolated by gel filtration and deae-cellulose chromatography from a cell-free extract of bacillus amyloliquefaciens (b. subtilits) n strain; a lower molecular weight endonuclease (endonuclease r.bamni) and a higher molecular-weight one (endonuclease r.bamnx). both of them required only mg2+ for their activities. endonuclease r.bamnx introduced a larger number of site-specific scissions in excherchia coli phage lambda dna that endonuclease r.bamni did. ...	1976	182257
structure of a defective simian virus 40 genome bearing an operator from bacteriophage lambda.	we examined further the physical structure of the simian virus 40 (sv40) and bacteriophage lambda dna sequences in an sv40-lambda hybrid that had been propagated in monkey kidney cells. the sv40 vector portion of the hybrid, which was a small fragment isolated from a reiteration mutant of sv40, contained the site for initiation of sv40 dna replication. electron microscope heteroduplex and restriction endonuclease analyses revealed a tandem duplication of the sv40 vector segment linked to a 2,300 ...	1976	184298
dna gyrase: an enzyme that introduces superhelical turns into dna.	relaxed closed-circular dna is converted to negatively supercoiled dna by dna gyrase. this enzyme has been purified from escherichia coli cells. the reaction requires atp and mg++ and is stimulated by spermidine. the enzyme acts equally well on relaxed closed-circular colicin e1, phage lambda, and simian virus 40 dna. the final superhelix density of the dna can be considerably greater than that found in intracellularly supercoiled dna.	1976	186775
construction of hybrid viruses containing sv40 and lambda phage dna segments and their propagation in cultured monkey cells.	this paper describes the successful construction and propagation of a transducing animal virus. a segment of dna approximately 2 kilobases (kb) in length was removed from the late region of the sv40 genome by sequential cleavages with hpa ii and bam hi endonucleases (at 0.735 and 0.13, respectively, on the sv40 dna map). a segment of about 1.5 kb of lambda phage containing ori (the origin of lambda dna replication), the two structural genes cii and cro, and four transcriptional promoters, was in ...	1976	189942
escape synthesis of beta-galactosidase under the control of bacteriophage lambda.		1976	190407
a gal region mutant that requires camp for growth on galactose in an adenyl cyclase negative (cya delta) background.	strains of escherichia coli k12 that contain a deletion of the adenyl cyclase gen (cya delta), required for the synthesis of cyclic adenosine-3';5' monophosphate (camp), grow on galactose-containing minimal medium. a mutant was isolated that grows on this medium only if camp is added. the mutation (designated galp20) is linked to the gal operon region as determined by both generalized transduction with bacteriophage p1 and specialized transduction with bacteriophage lambda. studies with galp20 c ...	1977	190530
physical and genetic characterization of deletion mutants of simian virus 40 constructed in vitro.	mutants of simian virus 40 (sv40), with deletions ranging in size from fewer than 3 to 750 base pairs located throughout the sv40 genome, were obtained by infecting cv-1p cells with linear sv40 dna and dna of an appropriate helper virus. the linear dna was obtained by complete cleavage of closed circular dna with hae ii or bam hi endonuclease or partial cleavage with either hae iii endonuclease or nuclease s1, followed, in some cases, by mild digestion with phage lambda 5' -exonuclease. the foll ...	1977	198579
ribonucleic acid polymerase mutant of escherichia coli defective in flagella formation.	escherichia coli k-12 mutants that are resistant to bacteriophage chi, defective in motility, and unable to grow at high temperature (42 degrees c) were isolated from among those selected for rifampin resistance at low temperature (30 degrees c) after mutagenesis with n-methyl-n'-nitro-n-nitrosoguanidine. genetic analysis of one such mutant indicated the presence of two mutations that probably affect the beta subunit of ribonucleic acid (rna) polymerase: one (rif) causing rifampin resistance and ...	1977	199575
on the structure of the deo operon of escherichia coli.	a characterization of a specialized transducing lambda phage for the deo operon (lambdaddeo), and some composite cole1-deo plasmids is given in this paper. this includes localization of the rsmai, rhind/iii, rbami, and recori sensitive sites. the deo genes have been localized by construction of composite cole1-deo plasmids. using the dna fragments, obtained by digestion with recori and rhindiii, respectively, as templates in an in vitro protein synthesizing system, it has been possible to give t ...	1977	200836
characterization and classification of virus particles associated with hepatitis a. ii. type and configuration of nucleic acid.	virus particles banding at 1.34 g/ml in cscl and sedimenting at 160s in sucrose gradients were isolated from fecal specimens of patients suffering from hepatitis. in the presence of 4 m urea and about 90% formamide, these particles released linear nucleic acid molecules of the kinked appearance characteristic of single-stranded rna or single-stranded dna. they could be distinguished from the nucleic acid of phage lambda added to the preparation as a marker for double-stranded configuration. expe ...	1978	206731
a spectroscopic and electron microscopic examination of the highly condensed dna structures formed by denaturation in mg(clo4)2.	1. thermal denaturation in 1.5 m mg(clo4)2 of the dna from bacteriophage lambda results in four well-separated subtransitions, as monitored by the accompanying increase in absorbance. the midpoint of the hyperchromic spectrum is significantly lowered compared to either 1.5 m mgcl2 or 3.0 m naclo4. 2. the first two subtransitions are associated with the melting of the a . t-richest regions of the lambda dna, as revealed by electron micrographs following fixation with formaldehyde. 3. commencing ...	1978	207326
antagonists of dna gyrase inhibit repair and recombination of uv-irradiated phage lambda.	intracellular lambda dna (from edta-sensitive tandem duplication phages) was extracted from infected rec+ bacteria and scored for infectivity and recombination (loss of duplication) by transfection of reca recb spheroplasts and subsequent assay for edta resistance. when phage development was blocked by repressor or by antibiotics (chloramphenicol and/or rifampin), the apparent recombination frequency was about 0.1% above the background value for reca infections. prior irradiation of the phage gr ...	1978	212734
cloning of herpes simplex type 1 dna fragments in a bacteriophage lambda vector.	dna isolated from defective and nondefective virions of herpes simplex type 1 (hsv-1) (strain patton) was digested with restriction endonucleases, and the resulting dna fragments were inserted in the ek2 coliphage vector lambdagtwes . lambdab. the recombinant dna was encapsidated in vitro under p4 maximum containment conditions. these lambda-hsv1 hybrids were purified and amplified, and the dna was isolated in the p4 facility. dna, free of viable phage and bacteria, was removed from p4 condition ...	1979	216076
molecular cloning of polyoma virus dna in escherichia coli: lambda phage vector system.	the biological activity of recombinant phage and recombinant phage dna containing monomeric or dimeric polyoma dna inserts was examined in mice and cultured mouse cells. recombinant preparations containing a single copy of viral dna were invariably noninfectious; molecules containing a dimeric polyoma dna insert were at least seven orders of magnitude less infectious than polyoma virions after parenteral inoculation. no infection was detected with any recombinant preparation after oral administr ...	1979	217088
molecular cloning of polyoma virus dna in escherichia coli: oncogenicity testing in hamsters.	inoculation of suckling hamsters with 2 x 10(8) live cells of escherichia coli k12 strain chi1776, carrying the complete genome of polyoma virus in a recombinant plasmid, failed to induce tumors in any of 32 recipients. also, lambda phage dna and particles with a monomeric insert of polyoma dna did not induce tumors. purified recombinant plasmid dna, as well as phage particles and dna containing a head-to-tail dimer of polyoma dna, showed a low degree of oncogenicity, comparable to that of polyo ...	1979	224458
dna replication proteins of escherichia coli and phage lambda.		1979	225103
persistence of phage lambda dna in genomes of mouse cells transformed by lambda-carrying sv40 vectors.	to test the suitability of simian virus 40 (sv40) dna as a vector for inserting dna segments into the chromosomes of mammalian cells, an ecori-a fragment of bacteriophage lambda dna was covalently joined to a fragment of sv40 dna and used to transform mouse cells in culture. three independent, morphologically transformed clones were obtained that were positive for sv40 t-antigen by immunofluorescence staining. dna from each transformant was examined by restriction enzyme analysis and found to co ...	1979	225241
integrative recombination of bacteriophage lambda: requirement for supertwisted dna in vivo and characterization of int.		1979	226309
nicking-closing activity associated with bacteriophage lambda int gene product.	integrative recombination of bacteriophage lambda requires the action of the protein int, the product of the phage int gene. in this paper we show that highly purified int relaxes supercoiled dna. the association of this nicking-closing activity with int is shown by: (i) the cosedimentation of nicking-closing and recombination activities of purified int, (ii) the parallel inactivation of the two activities in purified int by both heat and a specific antiserum, and (iii) the alteration of both ac ...	1979	226979
deoxyribonucleic acid and outer membrane: strains diploid for the oric region show elevated levels of deoxyribonucleic acid-binding protein and evidence for specific binding of the oric region to outer membrane.	we have recently reported that part of the chromosomal deoxyribonucleic acid (dna) of escherichia coli is associated with the outer membrane fraction and that an outer membrane protein having a molecular weight of 31,000 probably is involved in this association (h. wolf-watz and a. norqvist, j. bacteriol. 140:43-49, 1979). we have now found that f' merodiploid strains containing two copies of the dna between bglb and ilv have increased levels of this protein and an increased amount of dna in the ...	1979	227835
search for a dna gyrase in mammalian mitochondria.	incorporation of labeled deoxynucleoside triphosphates into mtdna by isolated rat liver mitochondria has been shown previously to reflect dna replication. we have used this system to seek evidence for a mtdna gyrase. coumermycin, novobiocin, nalidixic acid, and oxolinic acid are known to be inhibitors of escherichia coli gyrase, to inhibit e. coli dna replication, to abolish colicin e1 replication, and to depress the supercoiling of phage lambda dna, the last two via inhibition of the dna gyrase ...	1979	227861
the form of the dna substrate required for excisive recombination of bacteriophage lambda.		1979	229232
nonspecific cleavage by restriction endonuclease r . eco k of bacteriophage lambda-dna.		1979	231440
a new host-vector system allowing selection for foreign dna inserts in bacteriophage lambda gtwes.	an improved vector (lambda gtwes.t5-622) for ecori fragments has been derived from ek2 vector lambda gtwes.lambdab' by replacing the lambda b fragment with two identical 1.1 md fragments from the pre-early region of bacteriophage t5. the new vector has two advantages which facilitate elimination of parental-type recombinants in an in vitro recombination experiment. firstly, the 1.1 md insert is too small to be re-inserted into lambda gtwes in a single copy. secondly the 1.1 md t5 fragment carrie ...	1979	231542
phage lambda receptor chromosomes for dna fragments made with restriction endonuclease i of bacillus amyloliquefaciens h.		1979	231662
in vitro insertion of the lambda attachment site into the plasmid rp4.	the region of the phage lambda chromosome containing the attachment site (p.p') and the genes int and xis, excised by the action of endonuclease r.ecori, has been inserted into the unique site for that enzyme on the promiscuous conjugative plasmid, rp4, generating the recombinant plasmid rp4att lambda. transformants containing the hybrid plasmid were recognised by their ability to allow efficient lysogenization by phage lambda b2 (weil and signer, 1968; echols et al., 1968) containing the mutant ...	1979	231725
use of the lambda phage promoter pl to promote gene expression in hybrid plasmid cloning vehicles.		1979	232223
[integration of lambda phage (author's transl)].		1979	233426
characterization of lambda escherichia coli hybrids carrying chemotaxis genes.	molecular cloning techniques were used to construct hybrid escherichia coli lambda phage and isolate col e1 factors that carried the cheb region of the e. coli genome. the products of these genes were examined by using a series of deletions in the phage to stimulate specific polypeptide synthesis in ultraviolet-irradiated cells and by using col factor to program protein synthesis in minicells. seven flagellar related polypeptides were synthesized. three of these with apparent molecular weights o ...	1977	233725
a deoxyribonuclease of diplococcus pneumoniae specific for methylated dna.	a deoxyribonuclease specific for methylated dna was isolated from diplococcus pneumoniae. the enzyme, an endonuclease, degrades dna for escherichia coli to fragments of average molecular weight about half a million; it forms discrete fragments from phage lambda dna. methyl-deficient e. coli dna is not attacked, neither is dna from micrococcus radiodurans, which contains no methylated adenine or cytosine. nor is dna from d. pneumoniae or phage t7 attacked. however, dna from m. radiodurans, d. pne ...	1975	236309
gene transfer to human cells: transducing phage lambda plac gene expression in gmi-gangliosidosis fibroblasts.	genetic information from the bacterium escherichia coli was transferred to human cells by means of the specialized transducing phage lambda plac carrying the bacterial z gene for the enzyme beta-galactosidase (geta-d-galactoside galactohydrolase, ec 3.2.1.23). as recipient cells, cultured skin fibroblasts from a patient with generalized gangliosidosis (gmi-gangliosidosis type i) characterized by a severe deficiency of beta-galactosidase activity were used. the deficient human cells were incubate ...	1975	242006
nucleotide sequence of cro, cii and part of the o gene in phage lambda dna.	a nucleotide sequence comprising 960 base pairs of bacteriophage lambda dna has been determined. the sequence includes the entire genes of the regulatory proteins cro and cii, and part of the o gene, together with control elements for their transcription and translation. the right-hand boundaries of the lambdaimm434 and lambdaimm21 substitutions and the cy42 mutation have been located.	1978	264238
initiation of genetic exchanges in lambda phage--prophage crosses.	when escherichia coli k-12 (lambda) lysogens were infected with lambda phages, genetic exchanges between phage and prophage occurred at low frequencies (less than 0.1% between the markers p3 and p80), but at frequencies above 1% if the infecting phages were first treated with the photosensitizing agent 4,5',8-trimethylpsoralen and 360 nm light. exchanges were induced by psoralen damage at about the same frequency in wild-type lysogens and in those carrying recb(-), recc(-), recf(-), or lexa(-), ...	1977	264683
a thermostable sequence-specific endonuclease from thermus aquaticus.	a sequence-specific endonuclease, taq i, of novel specificity has been partially purified from an extreme thermophile, thermus aquaticus. the enzyme cleaves bacteriophage lambda dna at many (greater than 30) sites and bacteriophage psix174 rf dna at 10 sites. the enzyme is active at temperatures up to 70 degrees. the cleavage sites on psix174 rf dna have been mapped. the sequence recognized and cleaved by taq i has been shown to be the symmetrical tetranucleotide: (formula: see text).	1977	265518
assembly of biologically active proheads of bacteriophage lambda in vitro.	bacteriophage lambda dna can be packaged in vitro into preformed proheads to generate plaque-forming units. this complex set of reactions is initiated when lambda dna is mixed with the product of the phage a gene, and proheads. because proheads are an essential early reactant, the system has potential as an assay for the formation of biologically active proheads. when extracts of cells infected with certain lambda head mutants (for example, b--, c--, nu3--, and e--) are used as the prohead donor ...	1977	265585
characterization of the integration protein of bacteriophage lambda as a site-specific dna-binding protein.	the int protein specified by bacteriophage lambda is required for the recombination event that integrates the viral dna into the host genome at its specific attachment site. using a dna-binding assay, we have partially purified the int protein and studied some of the features of its binding specificity and regulation. the dna-binding activity is attributed to int protein because the activity is eliminated by a nonsense mutation or a deletion in the int gene, and is rendered thermolabile by tempe ...	1977	266191
cloning specific segments of the mammalian genome: bacteriophage lambda containing mouse globin and surrounding gene sequences.	we have developed a general approach to the cloning of specific segments of the mammalian genome that involves a two-step purification of ecori fragments of mammalian dna and their in vitro insertion into a suitably constructed ek2 derivative of bacteriophage lambda. the combination of fragment purification, exclusion of parental-type recombinants, and simple phage screening techniques permits the isolation of virtually any gene segment for which there is an identifying hybridization probe. we i ...	1977	270684
discrete length classes of dna depend on mode of dehydration.	the length of double-stranded coliphage lambda dna, as determined by electron microscopy using the benzyldimethylalkyl ammonium chloride technique, depends on the mode of dehydration. the freeze-dried dna form is the longest (16.5 micron), whereas dehydration in methanol (15.9 micron) or in ethanol (three forms: 15.2 micron, 13.9 micron, and 12.4 micron) results in progressively shorter molecules. these measured lengths of the freeze-dried, methanol-dehydrated, and shortest ethanol-dehydrated fo ...	1978	273234
mechanism of action of the cro protein of bacteriophage lambda.	the mechanism of action of cro protein was probed by measuring its ability to protect dna against methylation by dimethyl sulfate and its effect on transcription in vitro. the cro protein binds to the same three sites in the right operator (or) of bacteriophage lambda dna as does the lambda repressor. dimethyl sulfate protection experiments reveal major groove contacts for both proteins, and cro protein protects from methylation a subset of those purines protected by lambda repressor. these expe ...	1978	273909
nucleotide sequences of the separate origins of synthesis of bacteriophage g4 viral and complementary dna strands.	bacteriophage g4 has physically separated origins of synthesis of its viral and complementary dna strands. chain termination and "plus and minus" dna sequencing methods have been used to obtain the nucleotide sequence of these two origins. the unique origin at which the complementary dna strand is initiated has located in the untranslated region between genes f and g. this sequence, which has considerable secondary structure, contains a stretch which is complementary to the rna primer that is ob ...	1978	274698
chromosomal integration of phage lambda by means of a dna insertion element.	phage lambdacam112, which contains the chloramphenicol resistance transposon tn9 and has a deletion of attp and the int gene, will lysogenize escherichia coli k-12. prophage integration occurs at different chromosomal sites, including lacy and malb, but not at attb. all lambdacam112 prophages are excised from the chromosome after induction but with various efficiencies for different locations. heteroduplex analysis of lambdaplacz transducing phages isolated from a lacy::lambdacam112 prophage rev ...	1978	274736
identification of the n gene protein of bacteriophage lambda.	the n gene protein, pn, of bacteriophage lambda stimulates early gene transcription by allowing mrna chain elongation to proceed into genes distal to transcription termination sites normally recognized by the escherichia coli transcription termination protein rho. pn has previously eluded detection on sodium dodecyl sulfate/polyacrylamide gels because of its small size, its instability, and the difficulty of distinguishing pn itself both from host proteins and from other early lambda proteins wh ...	1978	276863
the cloning of mouse globin and surrounding gene sequences in bacteriophage lambda.		1978	277326
enzymatic breakage of the cohesive end site of phage lambda dna: terminase (ter) reaction.	an in vitro system is described for measuring the endonucleolytic conversion of the phage lambda cohesive end sites in concatemeric dna to the cohesive chromosomal ends of the mature molecule. this enzymic process, known as the ter reaction, is catalyzed by purified lambda a gene protein. the reaction is markedly stimulated by atp, mg2+, spermidine, and one or more uncharacterized factors present in extracts of uninfected escherichia coli cells. in vitro, the ter reaction proceeds in the absence ...	1978	279909
interaction of bacteriophage lambda repressor with nonoperator dna containing single-strand gaps.	in direct binding assays, purified lambdaind+ repressor displayed high affinity for nonoperator dna containing single-strand gaps. its affinity for this same dna but completely double-stranded, nicked, or denatured was considerably lower. in contrast, purified lambdaind- repressor had 1/10th the affinity for the gapped dna, a level comparable to that of purified lac repressor. in the presence of limiting amounts of ind+ repressor, nonoperator dna containing gaps could be shown to compete effecti ...	1978	282604
a single base-pair change creates a chi recombinational hotspot in bacteriophage lambda.	x4+ mutations, responsible for the chi phenotype in phage lambda, locally increase the rate of recombination promoted by the escherichia coli recombination system (rec). x+ mutations in the cii gene, one of a few sites in lambda at which such mutations arise, were located genetically and physically with overlapping deletions. dna sequence analysis of the deletion segment containing the x+ c mutations showed that two independent x+ c mutations arose by the same a-t to t-a transversion. presumably ...	1978	282634
location of the regulatory site for establishment of repression by bacteriophage lambda.	during the lysogenic response to infection by bacteriophage lambda, the phage-specified cii and ciii proteins provide for the coordinate establishment of repression and integration of the viral dna. one critical regulatory function of cii/ciii is an activation of synthesis of the ci protein, the repressor that maintains lysogeny. the mechanism and site for regulation of the ci gene by cii/ciii have been a subject of controversy. the two principal hypotheses for cii/ciii action are: initiation of ...	1979	284327
construction and some properties of packageable plasmid f.	a derivative of plasmid f which is packageable in lambda phage coat was constructed using techniques of in vitro recombination. this plasmid is composed of three dna fragments generated by restriction enzyme ecori: a minif fragment (fragment f5 of f'lac) which is able to replicate autonomously, a dna fragment from staphylococcus plasmid that carries the beta-lactamase gene, and a portion of guaa (b) transducing lambda phage dna carrying lambda cohesive ends (cos site) along with almost all the ...	1979	286145
n-independent leftward transcription in coliphage lambda: deletions, insertions and new promoters bypassing termination functions.	lambda mutants capable of n-independent red-gam gene expression were isolated by selecting fec+ plaque-forming derivatives of lambda n+ nutl- (fec-) strains. in addition to true nutl+ reversions, three classes of second-site mutations were identified: (1) ninl deletions that remove a region containing either tl1 or both tl1 and tl2 termination signals, or only a small region (defining the rut site) just upstream from tl1, (2) new constitutive promoters that map just upstream from the tl2 termina ...	1979	286866
the lambda repressor contains two domains.	papain digestion of the lambda phage repressor produces two fragments that are relatively resistant to further digestion. one includes the amino terminus (residues 1-92) and the other the carboxyl terminus (residues 132-236). calorimetry shows that the amino-terminal fragment denatures near 50 degrees c and that the carboxyl-terminal fragment denatures near 70 degrees c. intact repressor undergoes two denaturations, one near 50 degrees c and another near 70 degrees c. these and other data show t ...	1979	287002
molecular model for the transposition and replication of bacteriophage mu and other transposable elements.	a series of molecular events will explain how genetic elements can transpose from one dna site to another, generate a short oligonucleotide duplication at both ends of the new insertion site, and replicate in the transposition process. these events include the formation of recombinant molecules which have been postulated to be intermediates in the transposition process. the model explains how the replication of bacteriophage mu is obligatorily associated with movement to new genetic sites. it po ...	1979	287033
cell-cycle-associated rearrangement of inverted repeat dna sequences.	inverted repeat dna sequences of caulobacter crescentus have been isolated, characterized, and cloned in a bacteriophage lambda vector. both whole populations and individual clones of these sequences were hybridized to restriction endonuclease-generated fragments of chromosomal dna isolated from cells that were in different stages of the cell cycle. some inverted repeat dna sequences were observed to hybridize to different regions of the chromosomal dna isolated from the morphologically and bioc ...	1979	293718
evidence against the reversion of mutation in the haemophilus influenzae phage hp1c1 by preinfection treatment of host cells or phage with mnng.	n-methyl-n'-nitrosoguanidine (mnng) causes reversion of a temperature-sensitive mutation in a bacteriophage of haemophilus influenzae if exposure to the mutagen takes place after infection but before lysis. however, neither pre-infection treatment of the phage dna, host cells, or both will cause reversion. the reasons for this are discussed in relation to the somewhat different results in the escherichia coli lambda phage system and in relation to error-prone repair and replication processes.	1978	306062
genetic inversion in the formation of an hfr strain from a temperature-sensitive f' gal strain.	an hfr strain (pb15) that carries a duplicated copy of the galactose operon genes flanking the integrated sex factor is unusually stable since it does not show excision of the repeated deoxyribonucleic acid segment. the right-hand galactose operon is in the normal orientation. deletion mutations that eliminate the right-hand galactose genes, the sex factor, and some of the left-hand operon have been isolated. mutants believed to have their left-hand galactose operon inverted were able to be indu ...	1977	318642
lambdoid phages that simplify the recovery of in vitro recombinants.	derivatives of phage lambda are described for use as vectors for fragments of dna generated with the hindiii and ecori restriction enzymes. with some vectors, hybrid molecules are recognised by a change from a turbid to a clear plaque morphology resulting from the insertion of a fragment of dna into the lambda gene coding for the phage regressor. other vectors contain a central, replaceable fragment of dna which imparts a readily recognisable phenotype. this central fragment may include either a ...	1977	319344
a mutant of escherichia coli showing constitutive expression of the lysogenic induction and error-prone dna repair pathways.	a mutant of e. coli (designated the sts mutant) has been isolated in which the phage induction and error-prone dna repair pathways appear to be expressed constitutively without the cells having received an inducing signal. phage lambda was not able to lysogenize this mutant, whereas a noninducible mutant of lambda, lambdaciind-, known to synthesize a repressor that is insensitive to the induction mechanism, lysogenized it normally. this result suggested that normal phage repressor was synthesize ...	1977	319458
isolation and characterization of lambda pleu bacteriophages.	in the escherichia coli lysogen hfrh73 described by shimada et al. (1973), none of the enzymes coded for by the leucine operon is synthesized due to an insertion of phage lambda into cistron leua. the orientation of lambda in the chromosome is ara leudcb lambda jan leua. after heat induction of the lysogen, plaque-forming transducing phages of two types are formed at low frequency. one type (e.g., lambda pleu9) transduces leud, leuc, and leub strains to prototrophy. the other type (e.g., lambda ...	1977	320178
antitermination and absence of processing of the leftward transcript of coliphage lambda in the rnaase iii-deficient host.		1977	320345
induced reactivity of uv-damaged phage gamma in e. coli k12 host cells treated with aflatoxin b1 metabolites.	the metabolites of aflatoxin b1, the most potent hepatocarcinogen so far known, promote in e. coli k12 cells the reactivation of phage lambda damaged by ultraviolet (uv) radiation. this reactivation process is error prone; 25% of the phage dna lesions are repaired, but mutagenesis, scored as clear plaque formation, is increased as much as 10-fold. such reactivation of uv-damaged phage lambda, which occurs in wild-type and in uvra but not in reca bacteria, is inducible: phage reactivation is obta ...	1977	320463
tn402: a new transposable element determining trimethoprim resistance that inserts in bacteriophage lambda.	we have found that the trimethoprim resistance determinant of the incp plasmid r751 (jacob et al., 1977; jobanputra and datta, 1974) transposes to bacteriophage lambda. we call this transposable element tn402.	1977	321437
the elongation factor tu coded by the tufa gene of escherichia coli k-12 is almost identical to that coded by the tufb gene.	radioactive elongation factor tu coded by either the tufa or the tufb gene of escherichia coli k-12 was isolated from cells incubated with a mixture of radioactive amino acids after infection with the defective lambda phage particles that carry either of these genes. two-dimensional chromatographic analyses of tryptic digests of the tufb gene product revealed about 50 radioactive spots. these same spots plus an additional one were also found in tryptic digests of the tufa gene product. furthermo ...	1977	321450
uv-induced alleviation of k-specific restriction of bacteriophage lambda.	a partial release of k-specific restriction of phage lambda grown in escherichia coli c was observed when e. coli k strains ab1157 (having wild-type repair of uv-produced dna damage) and ab1886 (uvra) were irradiated with uv light before infection. the effect occurred in ab1886 at lower uv fluences than it did in ab1157. little or no release of restriction was observed when ab2463 (reca) or ab2494 (lex-1) was used. such release of restriction appears to be another of the uv-induced phenomena ass ...	1977	321803
induction of protein x in escherichia coli.	certain treatments that damage dna and/or inhibit replication in e. coli have been reported to induce synthesis of a new protein, termed protein x, in reca+ lexa+ strains. we have examined some of the treatments that might induce protein x and we have, in particular, tested the hypothesis of gudas and pardee (1975) that dna degradation products play an essential role in the induction process. we confirmed that uv irradiation, nalidixic acid treatment, or thymine starvation result in protein x sy ...	1977	321932
effects of ribosomal mutations on the read-through of a chain termination signal: studies on the synthesis of bacteriophage lambda o gene protein in vitro.	in a dna-dependent protein-synthesizing system that contains streptomycin-sensitive ribosomes, lambda dna directs the synthesis of two proteins that are products of the o gene. the larger is produced as a result of read-through of a uga termination codon. in the system containing streptomycin-resistant ribosomes this read-through protein is not synthesized, indicating that the mutational alteration in the ribosomal protein s12 restricts the read-through. the mutant ribosomes also fail to synthes ...	1977	322139
isolation and characterization of conditional-lethal rho mutants of escherichia coli.	temperature-sensitive nita (rho) mutants of e. coli were isolated; one of them was characterized as an amber mutant. these strains show the nit phenotype (transcription of phage lambda dna independent of the n gene) at low temperatures and are inviable at high temperatures. the mutated sites appear to be between cya and mete on the chromosome. temperature-sensitive nita bacteria not only permit leftward transcription of the lambda genome at a high rate in the absence of the lambda n protein, but ...	1977	322147
ek2 derivatives of bacteriophage lambda useful in the cloning of dna from higher organisms: the lambdagtwes system.	a derivative of bacteriophage lambda has been modified and tested together with an appropriate host system to meet the criteria of ek2 biologic containment for cloning dna from higher organisms. in this report certain of the safety features are summarized and some of the tests carried out to confirm the containment properties of the vector are described. the cloning efficiency of this system, together with available gene purification and hybrid screening technology, indicate that it can be used ...	1977	322278
[dna modification in vitro by e. coli c and e. coli mre 600 dna-cytosine-methyltransferases: increased resistance of bacteriophage lambda dna to the rii restriction system].		1977	322977
isolation and characterization of plaque-forming lambdadnaz+ transducing bacteriophages.	the escherichia coli dnaz gene, a deoxyribonucleic acid (dna) polymerization gene, is located 1.2 min counterclockwise from pure, at approximately min 10.5 on the e. coli map. from a lysogen with lamdaci857 integrated at a secondary attachment site near pure, transducing phages (lambdadnas+) that transduced a dnazts (lambda+) recipient to temperature insensitivity (ts+) were discovered. three different plaque-forming transducing phages were isolated from seven primary heterogenotes. genetic test ...	1977	323235
mutagenesis of lambda phage: 5-bromouracil and hydroxylamine.	mutagenesis by 5-bromouracil of lambda phage to clear plaque formers does not depend on the reca function of the host e. coli cell or on the red function of the phage. pretreatment of the host cells with ultraviolet light does not affect bromouracil mutagenesis of the adsorbed phage. mutagenesis by hydroxlamine to clear plaque formers takes place at a high level in reca- host cells, and is not changed by preirradiation of of rec+ (wild type) hosts with ultraviolet light. thus, bromouracil and hy ...	1977	325384
transcription in vitro of bacteriophage lambda 4s rna: studies on termination and rho protein.	when bacteriophage lambdapga18 dna is transcribed in a purified in vitro system by e. coli rna polymerase (nucleoside triphosphate: rna nucleotidyl-transferase, ec 2.7.7.6), several major transcripts are synthesized. we have investigated transcriptional termination of one of these transcripts, the 4s, or "oop" rna. analysis by two-dimensional "fingerprinting" of t1 oligonucleotides reveals that transcription of the 4s rna terminates at a specific site on the lambdapga18 dna template, t-l with an ...	1977	325526
genetic characterization of plasmid formation by n- mutants of bacteriophage lambda.		1977	325881
amber mutants in the o gene of bacteriophage lambda are not efficiently complemented in the absence of phage n function.		1977	325882
analysis of the phase variation in lambda reduced immunity lysogens.	two distinct phases characterized by different levels of immunity that appear in some e. coli strains lysogenic for reduced immunity mutants of bacteriophage lambda are identified as single and tandem double lysogens respectively on the basis of dna-dna hybridization experiments and the requirement of the phage xis function for the transition from a single to a double, and of the host reca function for the transition from a double to a single lysogen (in a xis- condition). rim lysogens with a fu ...	1977	327265
a specialized transducing lambda phage carrying the escherichia coli genes for phenylalanyl-trna synthetase.	a lambda phage has been isolated which specifically transduces the escherichia coli phes and phet genes coding for the alpha and beta subunits of the phenylalanyl-trna synthetase (prs). this phage transduces with high frequency (i) several temperature-sensitive prs mutants to thermoresistance and (ii) a p-fluorophenylalanine resistant prs mutant to sensitivity against this amino-acid analog. the in vitro prs activities of such lysogens suggest that the alpha and beta subunits coded by the transd ...	1977	327276
[the action of selected herbicides on bacteriophages and escherichia coli (author's transl)].	the effect of eight herbicides on the multiplication of bacteria and bacteriophages was tested with escherichia coli, strains w1665f+ and c600, and with the rna-phage m12 and the dna-phage lambda in turbidimetric investigations and one-step growth experiments. e. coli is inhibited by seven of the herbicides investigated in concentrations of 10(-3)m, partly of 10(-4)m, too, and is promoted by some compounds in weaker concentrations. naphthylacetic acid, (nes) largely independent of its concentrat ...	1977	327728
r factor types found in salmonella typhimurium and escherichia coli isolated from calves in a confined environment.	typing of r factors by genetic properties was done with salmonella typhimurium and escherichia coli isolated from calves on a feedlot where epizootics of clinical or subclinical calf salmonellosis had repeatedly occurred during 5 years. forty-nine r factors from s typhimurium were fi- (no fertility inhibition) and spp- (no restriction against phage lambda vir). twenty-three (46.9%) of them belonged to compatibility group ialpha and the remainder were nontypable. fourteen r factors from e coli be ...	1977	327875
[interaction of the isolated dna of lambda phage with spheroplasts of e. coli treated with sturine].	the method of centrifugation in sucrose density gradient (30-55%) of the spheroplast membrane preparations treated and untreated with sturine and infected with phage lambda dna demonstrated that sturine, treatment increased the phage lambda dna absorption three-fold. about 50% of the lambda dna molecules adsorbed by spheroplasts are bound with the cytoplasmic membrane of spheroplasts treated with sturine; 50% of the lambda dna molecules are bound with the cell wall membrane on the sturine-untrea ...	1977	328079
inhibition of beta-galactosidase synthesis in escherichia coli after infection with different dna and rna phages.	infection of escherichia cooi with t1, t2r+, t3 and t4 phages leads to an immediate inhibition of beta-galactosidase synthesis. similar results were obtained with the virulent mutant of phage lambda. the degree of inhibition of beta-galactosidase synthesis depends on the time delay between the addition of the inducer and the phage particles, and on the amount of phage dna, which has penetrated into the host cell. rna phage ms2 exhibited no inhibitory effect on enzyme synthesis.	1977	328356
initiation of the dna replication of bacteriophage lambda in escherichia coli k12.		1977	328896
morphogenesis of bacteriophage lambda deletion mutants. i. abnormal head-related structures produced in normal escherichia coli.		1977	328899
morphogenesis of bacteriophage lambda deletion mutants. ii. escherichia coli mutants which prevent maturation of short genomes.		1977	328900
transcription of insertion elements is1 and is2 in vitro.	insertion elements is1 and is2 integrated within the gal operator-promoter region, an is1 element in gene galt and insertions is1 and is2 integrated in the xyciiop region of phage lambda were transcribed in vitro with e. coli rna-polymerase. the insertion elements are transcribed exclusively by polymerase molecules started at the gal promoter and the lambdapr promoter respectively. no promoter exists on is1 or is2 which can be recognized by rna-polymerase in the pure in vitro transcription syste ...	1977	329104
bacteria with defective rho factors suppress the effects of n mutations in bacteriophage lambda.	a prediction based on the model for n-gene function of bacteriophage lambda proposed by roberts (1971) is confirmed by showing that a lambdan- double mutant is able to grow in strains of e. coli with defective rho transcription termination factors. the burst sizes for lambdan- in these strains range from 5 to 24% the burst sizes for lambdan+ in the same strain. this low level of suppression is also evident in the levels of synthesis of the lambda exonuclease and is consistent with other evidence ...	1977	329106
repression of inducible enzyme synthesis in a mutant of escherichia coli k 12 deleted for the ptsh gene.	the genome of lambda phage with thermosensitive repressor was inserted into the pts region of the escherichia coli chromosome. this lysogenic culture possessed the pts1 phenotype at 30 degrees c. a mutant strain with a deletion covering the ptsh gene was isolated after a prophage curing procedure. the deletion nature of the pts mutation was confirmed in genetical and biochemical experiments. the deletion covered a small fragment of the bacterial genome not extending in the ptsi and lig genes. th ...	1977	329116
inactivation and proteolytic cleavage of phage lambda repressor in vitro in an atp-dependent reaction.	we have reproduced in vitro the inactivation of bacteriophage lambda repressor that occurs in vivo when a lambda lysogen is treated with agents such as ultraviolet radiation that attack dna. atp and a divalent cation are required for the inactivation reaction. the ind- repressor is insensitive to the inactivation mechanism. a proteolytic cleavage of repressor accompanies inactivation in vitro, as it does in vivo.	1977	329277
interrelationship of the phage lambda receptor protein and maltose transport in mutants of escherichia coli k12.		1977	329879
state of the gal-transducing hybrid phage lambda ci857nin5h424gal+ genome in klebsiella pneumoniae m5a1.		1977	330392
threonyl-transfer ribonucleic acid synthetase from escherichia coli: subunit structure and genetic analysis of the structural gene by means of a mutated enzyme and of a specialized transducing lambda bacteriophage.	threonyl-transfer ribonucleic acid synthetase (thrrs) has been purified from a strain of escherichia coli that shows a ninefold overproduction of this enzyme. determination of the molecular weight of the purified, native enzyme by gel chromatography and by polyacrylamide gel electrophoresis at different gel concentrations yielded apparent molecular weight values of 150,000 and 161,000, respectively. polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate yields a single prot ...	1977	330505
cro regulatory protein specified by bacteriophage lambda. structure, dna-binding, and repression of rna synthesis.	the cro protein specified by bacteriophage lambda is a repressor of the genes expressed early in phage development and is required for a normal late stage of lytic growth. we have purified cro protein to virtual homogeneity and analyzed its structure and properties as a dna-binding protein and repressor of rna synthesis. to confirm that the protein is the product of the cro gene, we have also shown that a missense mutation in the cro gene leads to a product that is more temperature- and salt-sen ...	1977	330523