Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| human t cell antigens involved in cytotoxicity against allogeneic or autologous chemically modified targets. association of the leu 2a/t8 antigen with effector-target cell binding and of the t3/leu 4 antigen with triggering. | monoclonal antibodies (mab) recognizing human t cell differentiation antigens were employed to analyze the role of these antigens on t cell-mediated cytotoxicity against autologous 2,4,6-trinitrophenyl (tnp)-modified targets. the okt3/anti-leu 4 and anti-leu 2a/okt8 mab inhibited t cell-mediated cytotoxicity against autologous or unrelated tnp-modified targets, in the absence of complement and at the effector cell level. these cytotoxic effector cells were t3+, t8+, t11+, t4-. to analyze the rol ... | 1984 | 6610558 |
| initiation site of deoxyribonucleotide polymerization at the replication origin of the escherichia coli chromosome. | a new round of chromosomal replication of a temperature-sensitive initiation mutant (dnac) of escherichia coli was initiated synchronously by a temperature shift from a nonpermissive to a permissive condition in the presence of arabinosyl cytosine. increased amounts of nascent dna fragments with homology for the chromosomal segment containing the replication origin (oric) were found. the nascent dna fragments were purified and treated with alkali to hydrolyze putative primer rna and to expose 5' ... | 1983 | 6191181 |
| escherichia coli can lacks a trna-processing nuclease. | escherichia coli strain can is unable to support the growth of bacteriophage t4 strains requiring the suppressor function of t4 trnaser. biochemical analysis of the mutant strain revealed that it is deficient in a rnase which acts on the artificial trna precursor trna-c-u. | 1983 | 6194149 |
| [primary structure of the elongation factor g from escherichia coli. vi. structure of peptides of cyanogen bromide cleavage of the g-factor molecule]. | peptides obtained as a result of cyanogen bromide cleavage of the g-factor have been studied. all 12 peptides embracing the whole structure of fragment t4 have been isolated. for their amino acid sequence determination, cyanogen bromide peptides have been further cleaved with trypsin, chymotrypsin, thermolysin, staphylococcal glutamic protease and bnps-skatole. the complete primary structure of 9 from 12 cyanogen bromide peptides has been determined. | 1983 | 6385997 |
| limited proteolysis studies on the escherichia coli single-stranded dna binding protein. evidence for a functionally homologous domain in both the escherichia coli and t4 dna binding proteins. | limited proteolysis can be used to remove either 42 or 62 amino acids at the cooh terminus of the 18,873-dalton escherichia coli single-stranded dna binding protein (ssb). since poly(dt), but not d(pt)16, increases the rate of this reaction, it appears that cooperative ssb binding to single-stranded dna (ssdna) is associated with a conformational change that increases the exposure of the cooh terminus to proteolysis. as a result of this dna-induced conformational change, we presume that the cooh ... | 1983 | 6298232 |
| studies on dna replication in the bacteriophage t4 in vitro system. | 1983 | 6305581 | |
| site-specific cleavage of bacteriophage t4 dna associated with the absence of gene 46 product function. | a plasmid containing a copy of the late gene 23 was cleaved at two specific locations after bacteriophage t4 infection. cleavage at the major site, which is at the 3' end of gene 23, was detected only in the absence of gene 46 product function and was independent of the state of modification of cytosine residues. cutting of plasmid (cytosine-containing) dna at this site was independent of phage dna replication and late transcription functions. a second cleavage site, in vector dna, was also mapp ... | 1983 | 6306283 |
| primary structure and genetic organization of phage t4 dna ligase. | the primary structure of phage t4 dna ligase has been determined by dna sequencing of a cloned restriction fragment containing its gene, and partial amino acid sequence analysis of the protein. the molecule has a mr of 55,230, and contains 487 amino acids. the dna sequence may also encode all of one and parts of two other, hitherto unidentified, t4 proteins. the four genes are closely packed, with overlaps between terminator and initiator codons of adjacent genes. potential terminator and promot ... | 1983 | 6314278 |
| mechanism of ribosome frameshifting during translation of the genetic code. | some frameshift mutations are strongly suppressed by limitation for particular aminoacyl-trna species. here, we show that ribosome frameshifting at a specific tryptophan codon during trp-trna limitation accounts for suppression of a group of downstream frameshift alleles in the riib gene of bacteriophage t4. genetic and physiological observations strongly suggest that ribosome frameshifting at this position depends on the binding of a noncognate (leucine) trna. | 1983 | 6339944 |
| stabilization of proteins by a bacteriophage t4 gene cloned in escherichia coli. | the cloned bacteriophage t4 pin gene functions to stabilize several different kinds of proteins in escherichia coli bacteria. incomplete proteins such as puromycyl polypeptides, abnormal but complete proteins such as the lambda phage tso protein, and labile eukaryotic proteins encoded by genes cloned in e. coli such as mature human fibroblast interferon are stabilized in cells in which the t4 pin gene is expressed. the cloned t4 pin gene does not seem to affect the turnover of normal e. coli pro ... | 1983 | 6340113 |
| ribonuclease bn: identification and partial characterization of a new trna processing enzyme. | a new ribonuclease, rnase bn, has been identified and partially purified from a strain of escherichia coli lacking rnase ii and rnase d by using the artificial trna precursor trna-c-[14c]u as substrate. this enzyme is present in e. coli b but absent from the trna processing mutant strain bn which is unable to process extraneous 3' residues on certain phage t4-specified trna precursors. the properties of rnase bn clearly distinguish this enzyme from other known e. coli exoribonucleases. it is opt ... | 1983 | 6344080 |
| circular permutation analysis of phage t4 dna by electron microscopy. | phage t4 is known to have a linear duplex chromosome that is circularly permuted and terminally repeated. we found, by denaturation and self-reannealing experiments, that circular permutation in t4 native dna is not random. their multimodal distribution of permutation is compatible with the "headful packaging" model with the additional specifications that the encapsulation of dna starts at several sites and these are not random distributed. | 1983 | 6346725 |
| r plasmid dihydrofolate reductase with a dimeric subunit structure. | dihydrofolate reductase specified by plasmid r483 from a trimethoprim-resistant strain of escherichia coli has been purified 2,000-fold to homogeneity using dye-ligand chromatography, gel filtration, and polyacrylamide gel electrophoresis. the protein migrated as a single band on nondenaturing polyacrylamide gel electrophoresis and had a specific activity of 250 mumol/mg min(-1). the molecular weight was estimated to be 32,000 by gel filtration and 39,000 by ferguson analysis of polyacrylamide g ... | 1983 | 6350298 |
| incorporation of thymine-containing dna precursors in plasmolysed cells infected by the t4 non-lethal recombination defective mutants. | incorporation of tdr is aberrant in cells plasmolysed 15 min after infection by the recombination defective t4 chi and omega mutants. the in situ results parallel those obtained in vivo: at high tdr concentrations both t4 chi and t4 omega induced incorporation is slightly reduced compared to wild type, whereas at low tdr concentration incorporation induced by t4 chi is reduced and that induced by t4 omega is increased compared to wild type. no differences between wild type and mutant induced tdr ... | 1983 | 6355762 |
| rapid hydrolysis of deoxynucleoside triphosphates accompanies dna synthesis by t4 dna polymerase and t4 accessory proteins 44/62 and 45. | 1982 | 6460024 | |
| effect of proofreading and dam-instructed mismatch repair systems on n4-hydroxycytidine-induced mutagenesis. | the role of the proofreading (3' leads to 5' exonuclease) function of t4 dna polymerase and the mismatch repair system of e. coli on n4-hydroxycytidine (oh4cyd) induced mutagenesis was investigated. oh4cyd-induced mutation is strongly suppressed when the proofreading activity increases as a result of the presence of tscb87--antimutator polymerase or elevated temperature (43 degrees c vs 30 degrees c). mutagenic activity of oh4cyd, however, is little, if at all, affected by the presence of the ts ... | 1982 | 6750321 |
| characteristics of a bacteriophage t4-induced complex synthesizing deoxyribonucleotides. | a preparation of bacteriophage t4-induced deoxyribonucleotide synthetase complex is described. this very large complex of enzymes can be separated by centrifugation at 100,000 x g, by sucrose step gradient centrifugation, or with molecular exclusion columns. by direct assay and by unidimensional and two-dimensional acrylamide electrophoretic separations the following t4-coded enzymes were shown to be associated with the complex: ribonucleoside diphosphate reductase, dcmp deaminase, dctp/dutpase, ... | 1982 | 6757252 |
| [functional activity of short fibrils of bacteriophage t4]. | 1982 | 6759084 | |
| thiol-beta-lactamase: replacement of the active-site serine of rtem beta-lactamase by a cysteine residue. | we describe a procedure by which the codon (agc) for the active-site serine-70 of pbr322 beta-lactamase (penicillinase, penicillin amido-beta-lactamhydrolase, ec 3.5.2.6) is altered to that for cysteine (tgc). the pertinent nucleotide bases, a-g-c-a, positions 410-413, of pbr322 are excised by treating a limited hgiai digest of pbr322 with the 3' leads to 5' exonuclease of t4 dna polymerase. the new sequence, t-g-c-a, is inserted in two steps. first, the kpn i molecular linker d(t-g-g-t-a-c-c-a) ... | 1982 | 6818541 |
| recombinational bypass of pyrimidine dimers promoted by the reca protein of escherichia coli. | reca protein, in the presence of single-stranded dna binding protein and atp, promotes the complete exchange of strands between circular single-stranded dna containing pyrimidine dimers and a homologous linear duplex, converting the pyrimidine dimer-containing single-stranded dna to a circular duplex. bypass of a pyrimidine dimer during the branch-migration phase of the reaction requires approximately 20 seconds, a rate 1/50th of that in the absence of the dimer. the circular duplex product is s ... | 1982 | 6954468 |
| [effect of freezing modes on the survival of escherichia coli bacteriophages]. | the object of this work was to study the effect of freezing down to--196 degrees c at different cooling and warming rates on the survival of t3, t4 and phix174 phages. phage particles survived when t3 phage was frozen at a rate of 20-400 degrees/min and phix174 phage at a rate of 20-45 degrees/min. the survival rate of t4 phage was highest when it was frozen at a rate of 45 degrees/min. the survival of the phages depended also on the regime of warming. the susceptibility of the phages to freezin ... | 1982 | 6216396 |
| isolation, properties and nucleolytic degradation of chromatin from escherichia coli. | a new procedure has been developed for the isolation of the chromosome complex, termed chromatin, from escherichia coli. the bacteria were subjected to low ionic strength and t4 lysozyme, followed by detergent treatment analogous to that employed for the isolation of eukaryotic chromosomes. the chromatin was an insoluble viscous material which contained approximately equal amounts of dna and rna. the protein content of the chromatin was almost three times greater than the nucleic acid content. e ... | 1982 | 6190986 |
| characterization of the free radical of mammalian ribonucleotide reductase. | mouse fibroblast 3t6 cells, selected for resistance to hydroxyurea, were shown to overproduce protein m2, one of the two nonidentical subunits of mammalian ribonucleotide reductase. packed resistant cells gave an epr signal at 77 k very much resembling the signal given by the tyrosine-free radical of the b2 subunit of escherichia coli ribonucleotide reductase. also, the m2-specific free radical was shown to be located at a tyrosine residue. of the known tyrosine-free radicals of ribonucleotide r ... | 1982 | 6279610 |
| template-prime-dependent turnover of (sp)-datp alpha s by t4 dna polymerase. the stereochemistry of the associated 3' goes to 5'-exonuclease. | t4 dna polymerase converts (sp)-2'-deoxyadenosine 5'-o-(1-thio[1-18o2]triphosphate) to 2'-deoxyadenosine 5'-o-[18o]-phosphorothioate in the presence of poly(d(a-t).poly(d(a-t)) template-primer. control experiments involving either omitting the poly(d(a-t)).poly(d(a-t) template-primer or employing the (rp)-2'-deoxyadenosine 5'-o-(1-thiotriphosphate) diastereomer showed no reaction. it is assumed, therefore, that this conversion as in the p--o case involves incorporation of the thionucleotide into ... | 1982 | 6282851 |
| independent locations of kinase and 3'-phosphatase activities on t4 polynucleotide kinase. | we have used two chemical modification reagents and three proteases to study the relationship between the two activities of t4 polynucleotide kinase. in each case, conditions were found where one of the two activities of the enzyme could be eliminated without greatly reducing the other. taken together, these data indicate that the two activities are catalyzed by amino acid residues located in separate active sites on the polypeptide chain. specific exopeptidase digestion indicates that the kinas ... | 1982 | 6288680 |
| bacteriophage t4-induced anticodon-loop nuclease detected in a host strain restrictive to rna ligase mutants. | the fate of host trnas during t4 bacteriophage infection was investigated with escherichia coli ctr5x, the only known host strain that is restrictive to rna ligase and polynucleotide kinase mutants. three ctr5x trna species were cleaved during infection. one was leucine trna1, which was cleaved in the extra arm, as reported elsewhere for e. coli b infected with bacteriophage t2 or t4. the other two were specific to e. coli ctr5x and were not cleaved in various other hosts. one of the cleaved ctr ... | 1982 | 6296815 |
| caffeine inhibits dna polymerase i from escherichia coli: studies in vitro. | caffeine inhibits the activity of dna polymerase i (e. coli) and its proteolytic large fragment in in vitro dna replication system. dna polymerase from micrococcus luteus is also equally inhibited by caffeine. the extent of inhibition was more with the activated adenovirus, t4 and calf thymus dna than with synthetic dna template-primers. results obtained from time-course studies indicated that caffeine inhibition reached maximum by 30 min of incubation. enzyme kinetic studies showed that inhibit ... | 1982 | 7039855 |
| sealing of gaps in duplex dna by t4 dna ligase. | single-strand gaps in dna molecules were found to be a substrate for t4 dna ligase. sealing of the gaps was optimal at the same conditions as ligation of blunt-ended dna molecules. spermidine at a concentration of 2 mm stimulated the ligation of gaps, as well as the joining of dna molecules with cohesive and blunt ends. in addition, spermidine reduced the optimal atp concentration. the ligation of single-stranded gaps was a slow process, reaching a plateau after several hours at 25 degrees c. ap ... | 1982 | 7041091 |
| two alternative mechanisms for initiation of dna replication forks in bacteriophage t4: priming by rna polymerase and by recombination. | we show that bacteriophage t4 has two alternative mechanisms to initiate dna replication; one dependent on escherichia coli rna polymerase (rna nucleotidyltransferase, ec 2.7.7.6), and one dependent on general recombination. continued dna synthesis under recombination-defective conditions was sensitive to rifampin, an inhibitor of rna polymerase. on the other hand, dna synthesis accelerated in spite of the present of rifampin if recombination occurred. | 1982 | 7041114 |
| demonstration of pyrimidine dimer-dna glycosylase activity in vivo: bacteriophage t4-infected escherichia coli as a model system. | an approach to the detection of pyrimidine dimer-dna glycosylase activity in living cells is presented. mutants of escherichia coli defective in uvr functions required for incision of uv-irradiated dna were infected with phage t4 denv+ or denv- (defective in the t4 pyrimidine dimer-dna glycosylase activity). in the former case the denv gene product catalyzed the incision of uv-irradiated host dna, facilitating the subsequent excision of thymine-containing pyrimidine dimers. isolation of these di ... | 1982 | 7045391 |
| in vitro transcription of bacteriophage t4 trna gene cluster from two different promoters. | analysis of primary transcripts made by escherichia coli rna polymerase on t4 dna containing an intact or partially deleted trna gene cluster demonstrates that the t4 trna genes are transcribed from two promoters differing in their strength. the stronger (p1) and the weaker (p2) promoters are located at distances of 1 kb and 1.5 kb from the trna genes, respectively. selective initiation of individual transcripts with dinucleotides shows that p1 and p2 promoters contain the sequences tat and cac ... | 1981 | 7220346 |
| polyamine biosynthesis in escherichia coli: construction of polyamine-deficient mutants. | previous work is summarized on the biosynthetic pathway for polyamines in escherichia coli. deletion mutants have been obtained in the various biosynthetic steps, resulting in cells with no polyamines. these mutants grow at one-third the rate of polyamine-supplemented cultures and can serve as suitable hosts for bacteriophages t4, t7, q beta, and f2. the major effects of polyamine deficiency in these polyamine-deficient strains are: (i) these cells do not serve as hosts for bacteriophage gamma a ... | 1981 | 7040834 |
| studies on t4-head maturation. 2. substrate specificity of gene-49-controlled endonuclease. | the substrate specificity of 49+-enzyme was investigated in vitro. the enzyme showed a marked preference for rapidly sedimenting t4 dna (greater than 1000 s) when helix-destabilizing proteins from escherichia coli or phage t4 were added to the reaction. regular replicative t4 dna (200-s dna) or denatured t4 dna was not cleaved by the enzyme in the presence of these proteins but if they were omitted from the reaction both dnas become good substrates for the enzyme. 200-s dna was cleaved at its na ... | 1981 | 6262078 |
| [biosynthesis of early enzymes induced by bacteriophage t4]. | the biosynthesis of early enzymes of dna-ligase, rna-ligase, dna-polymerase, polynucleotide kinase, exonuclease a induced by bacteriophage t4amn82 was studied. the maximal activity of dna-ligase was observed at the 60th min after the infection, while that of the other enzymes was revealed at the 90th min and reached 4, 45, 529, 120 and 78 units per mg of protein for dna-ligase, rna-ligase, polynucleotide kinase, dna-polymerase and exonuclease a, respectively. bacteriophage t4amn82 induced the ma ... | 1981 | 6271263 |
| rii cistrons of bacteriophage t4. dna sequence around the intercistronic divide and positions of genetic landmarks. | 1981 | 6273585 | |
| selective inhibition by harmane of the apurinic apyrimidinic endonuclease activity of phage t4-induced uv endonuclease. | 1-methyl-9h-pyrido-[3,4-b]indole (harmane) inhibits the apurinic/apyrimidinic (ap) endonuclease activity of the uv endonuclease induced by phage t4, whereas it stimulates the pyrimidine dimer-dna glycosylase activity of that enzyme. e. coli endonuclease iv, e. coli endonuclease vi (the ap endonuclease activity associated with e. coli exonuclease iii), and e. coli uracil-dna glycosylase were not inhibited by harmane. human fibroblast ap endonucleases i and ii also were only slightly inhibited. th ... | 1981 | 6273822 |
| postinfection control in t4 bacteriophage infection: inhibition of the rep function. | we suggest that the general mechanism by which t4 phage turns off host macromolecular synthesis involves specific phage proteins which react with key components in the synthetic pathway. support for this mechanism exists for the inhibition of host rna synthesis. here we note that the host rep function was inhibited after t4 phage infection. since rep functions are known to be involved in host dna replication, inhibition of rep might alter the course of host dna replication. | 1981 | 6112279 |
| efficiency of t4 dna ligase-catalyzed end joining after s1 endonuclease treatment on duplex dna containing single-stranded portions. | covalently closed-circular, superhelical sv4o dna was used in all experiments. ecori endonuclease- and hpaii endonuclease-generated unit-length linear duplex dnas were digested with s1 endonuclease under the conditions where single-stranded cna was completely converted into the acid-soluble form. these were subjected to an end-to-end joining test with t4 dna ligase. the ligation efficiency was significantly lower than that of the flush-ended linear duplex dnas which were generated by both hpai e ... | 1981 | 6171303 |
| processing of bacteriophage t4 trnas. the role of rnaase iii. | 1981 | 6175760 | |
| in vitro thermal inactivation of a temperature-sensitive sigma subunit mutant (rpod800) of escherichia coli rna polymerase proceeds by aggregation. | a temperature-sensitive mutant sigma subunit (rpod800) purified from escherichia coli was inactivated in vitro by temperatures in excess of 37 degrees c whereas wild type sigma remained stable up to 49 degrees c. both temperature-sensitive and wild type sigma formed multimeric aggregates upon thermal inactivation which were visualized by electron microscopy as polymeric chains. conditions favoring sigma monomer (low sigma concentration and binding to core polymerase) protected temperature-sensit ... | 1981 | 7007376 |
| [serologic affinity and specificity of action of pseudotuberculosis and coli-dysentery phages]. | the study of serological properties, specificity and the range of action has revealed affinity between y. pseudotuberculosis phages (pst, 3m, kotlyarova, 2344, 2391), some coliphages (t2, t3, t4) and sh. dysenteriae phage (dd iv). the existence of serovar iii of y. pseudotuberculosis phages has been established; to this serovar phage pst belongs. newly isolated 2344 and 2391 belong to serovar i. the problem of the existence of y. pseudotuberculosis phages as an independent group is discussed. | 1981 | 7023155 |
| visualization of dna in various phages (t4, chi, t7, phi 29) by ethidium bromide epi-fluorescent microscopy. | 1981 | 7028505 | |
| control of promoter utilization by bacteriophage t4-induced modification of rna polymerase alpha subunit. | after infection of escherichia coli cells, bacteriophage t4 induces several changes in the host dna-dependent rna polymerase. a well-characterized chemical change is a two-step adp-ribosylation of the enzyme's alpha subunit (1). in order to investigate the effect of this change on rna polymerase transcriptional properties in an in vitro system, we have reconstituted the enzyme from separated individual subunits which were obtained from normal or t4-modified rna polymerases. it is demonstrated th ... | 1981 | 7031602 |
| fine mapping of secondary structures of fd phage dna in the region of the replication origin. | a synthetic heptaribonucleotide, gaccccc, which is complementary to a unique site on fd bacteriophage dna, primes dna synthesis of fd by t4 bacteriophage dna polymerase. the rate of the gaccccc-primed dna synthesis was not uniform as reflected by the appearance of discrete dna fragments as replication intermediates on an alkaline agarose gel. after 10 minutes of synthesis a significant fraction of the dna product ran as a single band with a length of about 1960 nucleotides. we have isolated this ... | 1981 | 7031605 |
| t4 head assembly and high temperature. | 1981 | 7036182 | |
| assembly of bacteriophage t4 tail fibers: identification and characterization of the nonstructural protein gp57. | formation of both the tail fiber and the baseplate of bacteriophage t4 depends on the product of t4 gene 57. a single amber mutation in that gene causes loss of two t4-specific proteins. their molecular weights are 18,000 and about 6,000, respectively, based on their electrophoretic mobilities in sds-polyacrylamide gels. e. coli carrying a cloned t4 dna fragment of about 700 basepairs, which directs the synthesis of the smaller protein only, specifically supports the growth of gene 57 amber muta ... | 1981 | 7038383 |
| binding of ribosomes to linear and circular forms of the 5'-terminal leader fragment of tobacco-mosaic-virus rna. | the sequence of the 5'-terminal leader fragment preceding the aug codon in the rna of tobacco mosaic virus (tmv), tomato strain, sps isolate, has been determined. this rna, similarly to the rnas of the u1 and dahlemense strains of tmv [kukla et al. (1979) eur. j. biochem. 98, 61--66] has the 7-methylguanosine(5')triphospho(5')guanosine cap separated from the initiation codon by a long stretch of nucleotides devoid of guanosine residues. the rnase-t1-resistant 73-nucleotide-long leader fragment o ... | 1981 | 6783406 |
| surface charge and hydrophobicity of salmonella, e. coli, gonococci in relation to their tendency to associate with animal cells. | the surface charge and hydrophobicity of salmonella typhimurium, escherichia coli and neisseria gonorrhoeae bacteria have been compared with their tendency to associate in vitro with human polymorphonuclear leucocytes (pmnl) and hela cells in culture. it was found that lipopolysaccharide mutations in s. typhimurium or e. coli, yielding core-defective mutants, increased the surface hydrophobicity, as assessed by aqueous two-phase partitioning and hydrophobic interaction chromatography, and promot ... | 1980 | 6782659 |
| primary structure of escherichia coli trna uur leu. presence of an unknown adenosine derivative in the first position of the anticodon which recognizes the uu codon series. | the primary structure of escherichia coli trna uur le which recognizes the uu series of codons has been determined. the sequence is pg-c-c-c-g-g-a-s4u-g-g-u-g-g-a-a-d-c-gm-c-d-a-g-a-c-a-c-a-a-g-g-g-a-psi-u-n-a-a-ms2i6a-a-psi-c-c-c-c-u-c-g-g-c-g-g-c-g-u-u-c-g-c-g-c-u-g-u-g-c-g-g-g-t-psi-c-a-a-g-u-c-c-c-g-c-u-c-c--g-g-g-u-a-c-c-a. the chain length of trna uur leu is 87 residues, the same as other e. coli trna leu s and t4 phage-coded trna leus. its sequence is especially similar to that of e. coli ... | 1980 | 6986390 |
| effect of bacteriophage t4 nrd mutants on deoxyribonucleotide synthesis in vivo. | 1980 | 6987228 | |
| efficient in vitro replication of double-stranded dna templates by a purified t4 bacteriophage replication system. | a wide variety of double-stranded dna templates are replicated extensively in an in vitro dna replication system containing the purified proteins specified by seven t4 bacteriophage dna replication genes (32, 41, 43, 44, 62, 45, and 61). in favorable conditions, this multiprotein system catalyzes the synthesis of several copies of the input dna template in a 30- to 60-min incubation. the replication forks produced in vitro move in a highly processive fashion, at approximately the in vivo rate of ... | 1980 | 6989836 |
| induction of mutations in specific genes of bacteriophage t4 using cloned restriction fragments and marker rescue. | saturation of a specific region of a chromosome with conditional lethal mutations becomes increasingly difficult as the genome size of the organism increases. we show that mutagenesis of cloned genes followed by their re-integration into a non-mutagenized organism is a practical way to circumvent this difficulty. | 1980 | 6990202 |
| isolation and characterization of context mutations affecting the suppressibility of nonsense mutations. | secondary mutations which increase the efficiency of suppression of nonsense mutations in the riib cistron of bacteriophage t4 have been isolated. these secondary mutations, called context mutations, map at sites very close to the nonsense codon, possibly on the promotor distal side. in context-nonsense double mutants, the amount of suppressed gene product is increased approximately 10-fold. the context mutations examined can act on the uaa (ochre) nonsense allele as well as on the uag (amber) n ... | 1980 | 6991868 |
| transcription termination factor rho and t-even phage development. | a functional factor rho is necessary for t-even phage development; phages t2 and t4 require different degrees of rho activity. the rho inactivation by ts-mutations in e. coli causes a reduction of some early protein synthesis and an early formation of some proteins normally typical of a later stage. besides, it weakens the synthesis of some late proteins, impairs the capsid proteins maturation and sharply inhibits phage dna replication in infected cells. however, in the absence of a functional r ... | 1980 | 6991874 |
| a mutant of e. coli that restricts growth of bacteriophage t4 at elevated temperatures. | after nitrosoguanidine mutagenesis, a phage host defective (phd) mutant of e. coli hfrh was isolated that supported the growth of t4d wild-type bacteriophage at 30 degrees, but not at 40 degrees or higher. eleven independent spontaneous mutants of t4 (go mutants) were isolated that overcame the growth restriction at high temperature. all of these mutants were located within three percent recombination of a gene 39 amber mutation in the clockwise direction on the standard map. in mixed infections ... | 1980 | 6993283 |
| neighbour and temperature effects on base-analogue-induced mutation in phage t4. | the effects of neighbouring base pairs and of temperature on mutation frequencies were measured at nonsense sites in the t4rii region. 2ap-induced at leads to gc transition frequencies are insensitive to nearest-neighbour effects, while 5bu-induced ones are promoted by gc neighbours on the 5' side. the effect of temperature on 2ap- and 5bu-induced mutation frequencies shows no simple dependence on nearest neighbours. these results are incompatible with a unitary mechanism as explanation for the ... | 1980 | 6993847 |
| t4 ribonucleotide reductase. physical and kinetic linkage to other enzymes of deoxyribonucleotide biosynthesis. | this laboratory has described a multienzyme aggregate from t4 phage-infected escherichia coli which seems to participate in deoxyribonucleotide biosynthesis and efficient delivery of dna precursors to the replication apparatus. this paper describes improved methodology for isolation of this aggregate, and we present three lines of evidence supporting a role for ribonucleoside diphosphate reductase in functioning of the presumed complex. 1) ribonucleoside diphosphates are readily incorporated int ... | 1980 | 6995453 |
| electrochemical h+ gradient but not phosphate potential is required for escherichia coli infection by phage t4. | 1980 | 6997076 | |
| bacteriophage t4 gene transcription studied by hybridization to cloned restriction fragments. | 1980 | 6997494 | |
| molecular basis for substitution mutations. effect of primer terminal and template residues on nucleotide selection by phage t4 dna polymerase in vitro. | the dna-dependent conversion of incorrect deoxynucleoside triphosphate precursors to monophosphates (turnover) by bacteriophage t4 dna polymerase was determined using either poly(da) x (dt) or poly(dg) x (dc) homopolymer templates. competition between correct and incorrect triphosphates for incorporation into dna, and the use of chain-terminating dideoxynucleoside triphosphates enabled us to determine the amount of turnover occurring at the end of each strand of the homopolymer duplex (e.g. amou ... | 1980 | 7002928 |
| effects of growth conditions and mutations in rna polymerase on translational activity in vitro in escherichia coli. | the translational capacity in vitro in escherichia coli, using rna from phage r17 or q beta as messenger, is several times higher if the extracts are prepared from cells harvested in early exponential phase or grown under conditions of good aeration compared to if extracts are prepared from cells harvested in a later growth phase or grown under semi-aerobic conditions. in low activity extracts the production of phage replicase protein is preferentially affected. growth of a wild type strain unde ... | 1980 | 7003312 |
| the generation and analysis of clones containing bacteriophage t4 dna fragments. | 1980 | 6246245 | |
| control of early gene expression of bacteriophage t4: involvement of the host rho factor and the mot gene of the bacteriophage. | many early mrna species of bacteriophage t4 are not synthesized after infection of escherichia coli in the presence of chloramphenicol. this has been interpreted as a need for t4 protein(s) to be synthesized to allow expression of some early genes, e.g., those for deoxycytidinetriphosphatase, deoxynucleosidemonophosphate kinase and udp-glucose-dna beta-glucosyltransferase. in the experiments described here, early mrna of bacteriophage t4 was allowed to accumulate during chloramphenicol treatment ... | 1980 | 6251243 |
| studies on phage internal proteins. vi. interaction of bacteriophage t4 internal proteins with t4 dna in vivo and in vitro. | internal proteins are basic proteins bound to the dna of t4 coliphage. centrifugation in sucrose gradients was employed to isolate dna-internal proteins complexes formed in vitro. polyacrylamide gel electrophoresis of radioactive internal proteins in the presence of sodium dodecyl sulfate followed by autoradiography of the gels was used to identify the dna-bound proteins and to determine their respective abundance in these complexes as well as in the bacteriophage head. the internal proteins wer ... | 1980 | 6251515 |
| bacteriophage t4-related macromolecular synthesis under restriction of plasmid rts1. | rts1 is a plasmid which confers upon the host bacteria the capacity to restrict t4 bacteriophage growth at 32 degrees c but not at 42 degrees c. pulse-labeling of phage-infected cells showed that rts1 restricts the synthesis of t1 dna. despite efficient restriction of t4 phage growth and dna synthesis, infected escherichia coli 20so harboring rts1 synthesized both early and late t4 phage rna. synthesis of early t4 phage rna under restrictive conditions (32 degrees c) was almost equal to that fou ... | 1980 | 6255193 |
| the purification of nuclease-free t4-rna ligase. | rna ligase has been highly purified in good yields from bacteriophage t4-infected escherichia coli by a rapid and reproducible procedure. the enzyme is free of phosphomonoesterase and ribonuclease activities and is therefore suitable for the synthesis of oligoribonucleotides and for the labeling of the 3'-terminus of rna. greater than 90% of the protein in the enzyme preparation migrates as a single band on gradient polyacrylamide gels containing sodium dodecyl sulfate during electrophoresis. fo ... | 1979 | 219895 |
| a new system for studying molecular mechanisms of mutation by carcinogens. | a new system for studying the molecular mechanisms of mutation by carcinogens is described. the system involves (a) site-specific modification of the essential gene g in phi x174 replicative form dna by a combination of chemical and enzymatic steps; (b) production of mutant virus carrying a change at a single preselected site by transfection of spheroplasts with the site modified phi x174 dna; (c) detection and propagation of mutants using a host carrying the plasmid, p phi xg, that rescues all ... | 1979 | 227905 |
| construction and properties of a cell-free system for bacteriophage t4 late rna synthesis. | a cell-free system for synthesizing bacteriophage t4 late rna is described. the system, which is based on the "cellophane disc" technique introduced by schaller and co-workers (schaller, h., otto, b., nüsslein, v., huf, j., hermann, r., and bonnhoeffer, f. (1972) j. mol. biol. 63, 183-200), provides favorable conditions for t4 dna and rna synthesis in vitro. total rna synthesis can be sustained for more than 1 h at 25 degrees c and initiation of early and late rna chains occurs in vitro. the cap ... | 1979 | 368054 |
| s1 nuclease as a probe for the conformation of a dimeric trna precursor. | we have employed s1 nuclease to probe the structure of an intermediate in trna biosynthesis available only in radiochemical purity. the dimeric precursor to trnagln and trnaleu from bacteriophage t4 was digested with the single-strand specific nuclease, and the products of the reaction were compared with the s1 digestion products of the mature cognate trna's. quantitation and sequence analysis of the products revealed that the location and accessibility of s1 cleavage sites in the precursor were ... | 1979 | 369598 |
| dna replication with bacteriophage t4 proteins. purification of the proteins encoded by t4 genes 41, 45, 44, and 62 using a complementation assay. | the proteins encoded by bacteriophage t4 genes 41, 45, 44, and 62 are known from the genetic studies of epstein et al. ((1963) cold spring harbor symp. quant. biol. 28, 375--394) to be required for viral dna synthesis. a convenient assay for each of these proteins is described which is based on the specific stimulation by each protein of dna synthesis in extracts of escherichia coli infected with mutants of bacteriophage t4 unable to make that protein. the t4 41 protein, 45 protein, and the comp ... | 1979 | 376524 |
| replication of the linear mitochondrial dna of tetrahymena pyriformis. | 1. electron micrographs of the linear mtdna from tetrahymena pyriformis strain gl show linear molecules with a duplex 'eye' of variable size in the middle. this indicates that replication of this dna starts near the middle of the molecule and proceeds bidirectionally to the ends, as previously shown for the mtdna of strain st (arnberg, a.c., van bruggen, e.f.j., clegg, r.a., upholt, w.b. and borst, p. (1974) biochim. biophys. acta 361, 266-276). the mtdnas of these two strains have little base s ... | 1979 | 110348 |
| different specific activities of the monomeric and oligomeric forms of plasmid dna in transformation of b. subtilis and e. coli. | (1) the low residual transforming activity in preparations of monomeric, supercoiled, circular (ccc) forms of the plasmids pc194 and phv14 could be attributed to the presence in such isolates of a small number of contaminating multimeric molecules. (2) e. coli derived preparations of phv14, as in vitro recombinant plasmid capable of replication in both e. coli and b. subtilis, contain oligomeric forms of plasmid dna in addition to the prevalent monomeric ccc form. the specific transforming activ ... | 1979 | 113646 |
| role of polymeric forms of the bacteriophage phi x174 coded gene a protein in phi xrfi dna cleavage. | gene a of the phi x174 genome codes for two proteins, a and a* (linney, e.a., and hayashi, m.n. (1973) nature new biol. 245, 6-8) of molecular weights 60,000 and 35,000, respectively. the phi x a* protein is formed from a natural internal initiator site within the a gene cistron while the phi x a protein is the product of the entire a gene. these two proteins have been purified to homogeneity as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis. previous studies have shown that ... | 1979 | 158588 |
| site-specific mutagenesis using synthetic oligodeoxyribonucleotide primers: ii. in vitro selection of mutant dna. | a method for the in vitro selection of mutant dna has been devised as an adjunct to the recently developed method for the use of short enzymatically-synthesized oligodeoxyribonucleotides of defined sequence as site-specific mutagens for circular dna. the selection method uses the mutating oligodeoxyribonucleotide as a primer for escherichia coli dna polymerase i (large fragment) under conditions where there is preferential interaction with mutant dna template. after ligation using t4 dna ligase, ... | 1979 | 161246 |
| restriction in vivo. iii. general effects of glucosylation and restriction on phage t4 gene expression and replication. | 1979 | 380145 | |
| the effect of template secondary structure on vaccinia dna polymerase. | vaccinia virus dna polymerase will utilize a substrate consisting of phi x174 dna primed with a strand of a unique restriction fragment, but the reaction is inefficient. examination of the reaction products by alkaline agarose gel electrophoresis revealed a few discrete fragments, each corresponding to an extended primer strand. this result implies that specific barriers exist on the phi x174 template which impede, but do not completely halt, the progress of the enzyme. only a few per cent of th ... | 1979 | 381293 |
| purification and some properties of deoxyribonuclease whose synthesis is controlled by gene 49 of bacteriophage t4. | an enzyme which specifically cleaves very-fast-sedimenting dna of bacteriophage t4 is synthesized after infection of t4, and its synthesis is controlled by gene 49 [1,2]. this enzyme has been proved to be a dnase [2]. we have purified this dnase 3000-fold from extracts of e. coli infected with t4. the purified preparation was practically free from other dnases, and the dnase activity was not detectable in cells infected with a mutant defective in gene 49. the enzyme activity from cells infected ... | 1979 | 389625 |
| [asymmetry in the frequencies of reciprocal recombinants in crosses of t4 phage riib mutants]. | the frequencies of reciprocal recombinants in crosses between riib mutants of t4 phage were shown to differ from each other. in terms of the correction model, this asymmetry of genetic recombination was used to measure the comparative correctability of the mismatched regions to the wild type and to the mutant alleles. the data obtained are in quantitative agreement with the analogous values for the same mismatched regions determined by comparison of the markers located at the same site. this str ... | 1979 | 391644 |
| nucleotide sequence of the region required for maintenance of colicin e1 plasmid. | plasmids carrying various portions of colicin e1 plasmid (cole1) dna have been isolated in an attempt to determine the regions of cole1 dna which are required for maintenance of the plasmid in bacteria. to construct the plasmids, the dna of a cole1 derivative that contains a gene which controls ampicillin resistance was cleaved by the restriction endonuclease haeii. the digestion products were joined by t4 dna ligase and then used to transform bacteria to ampicillin resistance. the plasmid deriv ... | 1979 | 393952 |
| platinum(ii) complexes block the entry of t4 phage dna into the host cells. | the efficiency of multiplicity reactivation of t4 particles inactivated by platinum(ii) complexes is very low. the same is true for marker rescue and functional survival of genes. this can be at least partly explained by the inability of most inactivated virus particles to introduce their dna into the host cells as demonstrated by electron microscopy. conformational changes in the dna, formation of dna-dna and dna-protein cross-links and the damage of proteins participating in the injection proc ... | 1979 | 398750 |
| [interaction between alkaloids of claviceps purpurea and development of some bacteria and bacteriophages. preliminary experiments]. | it has been tested the bacteriolytic activity and the interaction among the development of the bacteriophage t4 and ergot alkaloids. it has been determined a bacteriolytic action on the bacterial stub "e. coli host of bacteriophage t4. it exist an interaction also among such alkaloids and the development of the bacteriophage t4, which appears through an increase of the quantity of lysis areas, becoming evident in solid bodies containing the lysing bacterium. further researches with other bacteri ... | 1979 | 400107 |
| gene expression and stability of mrna affected by dna-arrested synthesis in gene 59, 46, and 47 mutants of bacteriophage t4. | the effect of bacteriophage t4 gene 59 mutations (dna-arrested synthesis) on kinetics of dna synthesis, gene expression, and stability of mrna has been studied. when escherichia coli b was infected by a t4 gene 59 mutant, dna synthesis proceeded to increase linearly after initiation, but started to decrease at 8 min and was completely arrested at 12 min at 37 degrees c. at various incubation temperatures (20 to 42 degrees c), the initial rates and times of arrest of dna synthesis were different, ... | 1978 | 702642 |
| attachment of tail fibers in bacteriophage t4 assembly. purification, properties, and site of action of the accessory protein coded by gene 63. | 1978 | 344316 | |
| construction and properties of recombinant plasmids containing the rii genes of bacteriophage t4. | the ecori digestion products of phage t4 dna have been examined using a phage dna transformation assay. a 2.6 x 10(6) dalton fragment was found to contain the rii genes. this fragment was purified and then treated with hindiii endonuclease. the cleavage products were ligated to the vector plasmid pbr313 and viable recombinant plasmids recovered. a genetic assay was employed to demonstrate that the recombinants contained t4 dna and to localize on the phage genetic map the ecori and hindiii sites ... | 1978 | 345100 |
| functional compartmentation of dna precursors in t4 phage-infected bacteria. | 1978 | 348692 | |
| genetic and physiological characterization of escherichia coli k12 mutants (tabc) which induce the abortive infection of bacteriophage t4. | 1978 | 351929 | |
| selectivity of rna chain initiation in vitro. 1. analysis of rna initiations by two-dimensional thin-layer chromatography of 5'-triphosphate-labeled oligonucleotides. | a method for the rapid and quantitative analysis of 5'-terminal oligonucleotides of rnas made in vitro is described. the method involves synthesis of rna in the presence of [gamma-32p]atp or gtp, isolation of the rna, and digestion with t1 or pancreatic ribonucleases to release labeled 5'-triphosphate termanated oligonucleotides. the oligonucleotides are then subjected to chromatography on a polyethyleniminecellulose thin-layer system using 2 m licl, 0.01 m edta (ph 6.5) in the first dimension a ... | 1978 | 352390 |
| further characterization of the r plasmid rts1 and its mutant ptw2: replication and incompatibility of the plasmid. | incompatibility of the r plasmid rts1 and its replication mutant ptw2 was studied in reca host cells of escherichia coli. when the r plasmid r401, belonging to the same incompatibility group as rts1, was used as a test plasmid, r401 was eliminated preferentially from (rts-r401)+ cells irrespective of the direction of transfer. in contrast, ptw2 and r401 were mutually excluded. the decreased incompatibility of ptw2 was confirmed by a direct incompatibility test in which a derivative of rts1 expel ... | 1978 | 355218 |
| ionic strength perturbation kinetics of gene 32 protein dissociation from its complex with single-stranded dna. | equilibrium and kinetic studies of the interaction of gene 32 protein of t4 phage with single-stranded fd dna were performed monitoring the changes in protein fluorescence. from the fluorescence titrations, it was estimated that a monomer of gene 32 protein covered six nucleotide bases on the dna and the lower limit for the apparent association constant was 1.9 x 10(8) m-1 with a cooperative parameter of 10(3) in 0.1 m 2-amino-2-hydroxymethyl-1,3-propanediol hydrochloride (ph 7) at 25 degrees c. ... | 1978 | 359047 |
| glutathione-dependent enzyme reactions of the phage t4 ribonucleotide reductase system. | 1978 | 359548 | |
| role of lipopolysaccharide and outer membrane protein of escherichia coli k-12 in the receptor activity for bacteriophage t4. | lipopolysaccharide isolated from escherichia coli k-12 did not inactivate phage t4, although the cell envelopes with 1% sodium deoxycholate resulted in the release of cytoplasmic membrane proteins, 70% of the lipopolysaccharide, and almost all of the phospholipid. the reconstitution of phage receptor activity was achieved from deoxycholate-soluble and -insoluble fractions by dialysis against a solution of magnesium chloride. lipopolysaccharide was the only essential component in the deoxycholate ... | 1978 | 361717 |
| model for dna packaging into bacteriophage t4 heads. | the mechanism of dna packaging into bacteriophage t4 heads in vivo was investigated by glucosylation of hydroxymethylcytosine residues in a conditionally glucose-deficient host. cytoplasmic dna associated with partially packaged ts49 heads can be fully glucosylated, whereas dna already packaged into these heads is shown to be resistant to glucosylation. after temperature shift and completion of arrested packaging into the reversible temperature-sensitive ts49 head, the structure of the dna in th ... | 1978 | 364076 |
| an escherichia coli ribonuclease which removes an extra nucleotide from a biosynthetic intermediate of bacteriophage t4 proline transfer rna. | the biosynthesis of bacteriophage t4 trnapro, trnaser, and trnaile requires enzymatic removal of extra nucleotides from the 3' terminus of the respective precursor rnas. a ribonuclease activity capable of catalyzing such reactions has been partially purified from uninfected escherichia coli using an artificial precursor rna as substrate. a number of ribonuclease activities were resolved during purification. use of e. coli strain bn, a mutant known to be deficient in the relevant ribonuclease act ... | 1978 | 364422 |
| regulation of ribosome function following bacteriophage t4 infection. | 1978 | 210283 | |
| [selective binding of oligoribonucleotides by t7 phage induced rna-polymerase]. | it was shown previously that e. coli rna-polymerase being incubated with the random oligonucleotide mixtures of definite length binds certain oligoribonucleotides with the length greater than or equal to 5 nucleotides. the data presented demonstrate that t7 phage induced rna-polymerase (t7 rna-polymerase) also binds selectively oligoribonucleotides beginning from pentaribonucleotides. from the random mixtures of penta-, hexa-, hepta-, octa-, nona- and decaribonucleotides the hepta- and octaribon ... | 1978 | 370554 |
| [topological model of bacteriophage-t4 dna replication]. | the structure and function of the dna--membrane complex in e. coli cells infected with bacteriophage t4 was studied. the dna--membrane complex was isolated from the cells pulse or uniformly labeled with 3h-thymidine, fractionated by detergent treatment and separated on a discontinuous sucrose gradient. the attachment of small dna fragments to the plasma membrane was analysed. replicating bacteriophage t4 dna was reversibly associated with the cytoplasmic membrane in the wall/membrane adhesion zo ... | 1977 | 377048 |
| equimolar addition of oligoribonucleotides with t4 rna ligase. | t4 induced rna ligase will join equimolar concentrations of two oligoribonucleotides, (ap)3c and p(up) 5, to form a single product, (ap)3cp(up) 5, in high yield. the presence of the 3' phosphate on p(up)5 prevents the oligomer from adding to itself. the ph optimum of the reaction is about 7.5, but less of the undesirable adenylated intermediate, app(up) 5, forms at ph 8.2. the reaction rate is a linear function of oligomer concentration from 3 micronm to 0.6 mm. the data suggest that t4 rna lig ... | 1977 | 17097 |
| restoration by t4 ligase of dna sequences sensitive to "flush" cleaving restriction enzyme. | fouteen "flush"-ended segments originate from the action of the restriction endonuclease hae iii of haemophilus aegiptius on the dna of the colicinogenic factor cole 1 (a. oka and m. takanami, nature, 264, 191, 1976). they are joined by the t4 polynucleotide ligase. the reaction can be monitored by gel electrophoresis, electron microscopy and resistance to phosphatase of the 5'-32p labelled ends. the joined products are a random recombination of the original segments, and can be cleaved by the s ... | 1977 | 198743 |
| slow switchover from host rna synthesis to bacteriophage rna synthesis after infection of escherichia coli with a t4 mutant defective in the bacteriophage t4-induced unfolding of the host nucleoid. | most, if not all, host rna synthesis was shut off after infection of escherichia coli strain b/5 with a bacteriophage t4 multiple mutant defective in the abilities to induce (i) unfolding of the host nucleoid (unf-), (ii) nuclear disruption (ndd-), and (iii) host dna degradation (dena-, denb-). the shutoff of host rna synthesis and turn-on of phage rna synthesis were slower after infection of e. coli with unf- phage than after infection with unf+ phage. this delay in the switchover from host rna ... | 1977 | 201776 |
| phage t4-modified rna polymerase transcribes t4 late genes in vitro. | initiation of t4 late rna synthesis has been achieved in an in vitro system prepared from escherichia coli cells infected with wild-type or maturation-defective mutant t4 phage. the system uses a cellophane membrane as a mechanical support for concentrated cell lysates and for added streptolydigin-resistant rna polymerases. transcriptional activity and selectivity of added rna polymerases are tested while endogenous rna polymerase activity is inhibited by streptolydigin. t4-modified rna polymera ... | 1977 | 271954 |