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roles of cys148 and asp179 in catalysis by deoxycytidylate hydroxymethylase from bacteriophage t4 examined by site-directed mutagenesis.the proposed roles of cys148 and asp179 in deoxycytidylate (dcmp) hydroxymethylase (ch) have been tested using site-directed mutagenesis. ch catalyzes the formation of 5-(hydroxymethyl)-dcmp, essential for dna synthesis in phage t4, from dcmp and methylenetetrahydrofolate. ch resembles thymidylate synthase (ts), an enzyme of known three-dimensional structure, in both amino acid sequence and the reaction catalyzed. conversion of cys148 to asp, gly, or ser decreases ch activity at least 10(5)-fold ...19921420151
cloning, sequencing, overproduction, and purification of m. cvibi (gantc) methyltransferase from chlorella virus nc-1a [corrected].we have cloned and sequenced the cvibim gene from chlorella virus nc-1a by selecting for the modification phenotype. the modification gene was cloned on a 7-kb bamhi fragment inserted into the bamhi site of the puc13 plasmid. the cvibim gene was localized at the 3' end of this fragment. sequencing of this region revealed a large open reading frame that codes for methyltransferase (mtase; symbol m.) (predicting 260 amino acids). m.cvibi (gantc) aa sequence is homologous to m.dam(gatc), m.dpnii(ga ...19921427082
molecular characterisation of a dna ligase gene of the extremely thermophilic archaeon desulfurolobus ambivalens shows close phylogenetic relationship to eukaryotic ligases.a 3382 bp fragment containing a gene for a dna ligase from the extremely thermophilic, acidophilic, and facultatively anaerobic archaeon (archaebacterium) desulfurolobus ambivalens was cloned and sequenced. the deduced amino acid sequence (600 amino acids, 67619 molecular weight) showed 30-34% sequence identity with the atp-dependent eucaryal (eukaryotic) dna ligases of schizosaccharomyces pombe, saccharomyces cerevisiae, the human dna ligase i, and with the vaccinia dna ligase. distant similari ...19921437556
in vitro characterization of repair synthesis initiated by t4 endonuclease v on a synthetic dna substrate.the size of the repair patch produced by e. coli dna polymerase (pol i) following the removal of a pyrimidine dimer from dna in response to the nicking activity of t4 endonuclease (t4 endo v) was determined. a 48-bp dna containing a pyrimidine dimer at a defined location was labelled in the damaged strand and incubated with t4 endo v and e. coli endonuclease iv. subsequently, dna synthesis by dna pol i was carried out in the presence of four dntps, atp and dna ligase. analysis of the reaction pr ...19921512008
critical functional role of the cooh-terminal ends of longitudinal hydrophobic strips in alpha-helices of t4 lysozyme.the sensitivity of bacteriophage t4 lysozyme function to amino acid substitutions at defined positions in and around the longitudinal, hydrophobic strips of 9 alpha-helices was assessed after systematic replacement of each residue in the protein with a series of 13 amino acids. the hydrophobic strips were defined by identifying the longitudinal sectors in the helices with the highest mean residue hydrophobicities. sensitivity to mutation (the percentage of replacements leading to loss of functio ...19921517218
effect of escherichia coli nusg function on lambda n-mediated transcription antitermination.the escherichia coli nus factors act in conjunction with the bacteriophage lambda n protein to suppress transcription termination on the lambda chromosome. nusa binds both n and rna polymerase and may also interact with other nus factors. to search for additional components of the n antitermination system, we isolated host revertants that restored n activity in nusa1 mutants. one revertant, nusg4, was mapped to the rif region of the e. coli chromosome and shown to represent a point mutation near ...19921531224
are there highly conserved dna polymerase 3'----5' exonuclease motifs?it was proposed by bernad et al. [cell 59 (1989) 219-228] and blanco et al. [gene 100 (1991) 27-38] that the 3'----5' exonuclease (exo) domain of escherichia coli dna polymerase i (poli) is structurally and functionally conserved among prokaryotic and eukaryotic dna polymerases. the basis for this claim is the presence of three short peptide sequences in many dna polymerases that resemble poli sequences that have been shown by x-ray crystallographic and genetic engineering studies to be metal io ...19921551593
recombinant human immunodeficiency virus type 1 nucleocapsid (ncp7) protein unwinds trna.the nucleocapsid protein (nc) of all animal retroviruses, encoded by the gag gene, is the major structural protein of the core ribonucleoprotein complex, bound to genomic rna in mature virions. nc is also thought to play one or more accessory roles in reverse transcription. mature nc (p7nc) from human immunodeficiency virus type 1 (hiv-1) is a 71-amino acid, basic protein which contains two cys3his zn(ii) retroviral-type zinc finger domains. herein, we describe the subcloning and expression of h ...19921551877
consequences of molecular engineering enhanced dna binding in a dna repair enzyme.facilitated one-dimensional diffusion is a general mechanism utilized by several dna-interactive proteins as they search for their target sites within large domains of nontarget dna. t4 endonuclease v is a protein which scans dna in a nonspecifically bound state and processively incises dna at ultraviolet (uv)-induced pyrimidine dimer sites. an electrostatic contribution to this mechanism of target location has been established. previous studies indicate that a decrease in the affinity of endonu ...19921567866
processive proofreading is intrinsic to t4 dna polymerase.dna replication occurs in vivo with very high processivity, meaning that the replication complex assembles at the origin(s) of replication and then performs template-directed synthesis of dna over virtually the entire genome without dissociation. such processivity also characterizes reconstituted replication holoenzyme complexes in vitro. however, the isolated dna polymerases are much less processive, especially under physiological conditions. in this paper we monitor the degree of processivity ...19921629215
immunoanalysis of ultraviolet radiation induced dna damage and repair within specific gene segments of plasmid dna.the region-specific heterogeneity of repairing dna damage has been established in several biological systems. a flexible and sensitive approach, based upon dna damage specific antibodies, is described to monitor the repair of specific lesions within discrete genomic segments. membrane transblotted dna restriction fragments are immunoanalyzed for the initial formation and repair of 254 nm radiation induced pyrimidine dimers. sensitivity of dimer immunodetection increases proportional to fragment ...19911657185
in vivo restriction. sequence and structure of endonuclease ii-dependent cleavage sites in bacteriophage t4 dna.endonuclease ii of bacteriophage t4 is required for in vivo restriction of cytosine-containing dna from its host, escherichia coli, (as well as from phage mutants lacking cytosine modification), normally the first step in the reutilization of host dna nucleotides for synthesis of phage dna in infected cells. the phage cytosine-dna is fragmented incompletely to yield genetically defined fragments. this restriction is different from that of type i, ii, or iii restriction enzymes. we have located s ...19911744134
folding of group i introns from bacteriophage t4 involves internalization of the catalytic core.fe(ii)-edta, a solvent-based cleavage reagent that distinguishes between the inside and outside surfaces of a folded rna molecule, has revealed some of the higher-order folding of the group ib intron from tetrahymena thermophila pre-rrna. this reagent has now been used to analyze the bacteriophage t4 suny and td introns, both of which are members of the group ia subclass. significant portions of the phylogenetically conserved secondary structure are protected from fe(ii)-edta cleavage. however, ...19911763026
[the role of temperature as a factor of structure and functional fit of a "prey" virus based on the example of phage t4].by means of high-precision acoustic measurements and by the methods of fluorescent and electron microscopy investigations were performed of thermoinduced conformational changes in t4 bacteriophage and its thermolabile mutants altered in baseplate proteins (gene products "7", "8", "10"). a relationship was found between the conformational changes in t4 bacteriophage structure in the temperature range of 33-45 degrees c and the efficiency of bacteriophage adsorption and changes in the orientation ...19911809394
stereochemical studies of the beta-elimination reactions at aldehydic abasic sites in dna: endonuclease iii from escherichia coli, sodium hydroxide, and lys-trp-lys.the dna strand cleavage reaction catalyzed by endonuclease iii from escherichia coli (endo iii) on the 3'-side of aldehyde abasic sites proceeds by a syn beta-elimination involving abstraction of the 2'-pro-s proton and formation of a trans alpha,beta-unsaturated aldose product; we previously reported the same stereochemical course for the reaction catalyzed by uv endonuclease v from bacteriophage t4 (uv endo v) [mazumder, a., gerlt, j. a., rabow, l., absalon, m. j., stubbe, j., & bolton, p. h. ...19911846560
oligonucleotide site directed mutagenesis of all histidine residues within the t4 endonuclease v gene: role in enzyme-nontarget dna binding.in order to evaluate the contributions that histidine residues might play both in the catalytic activities of endonuclease v and in binding to nontarget dna, the technique of oligonucleotide site directed mutagenesis was used to create mutations at each of the four histidine residues in the endonuclease v gene. although none of the histidines were shown to be absolutely required for the pyrimidine dimer specific dna glycosylase activity or the apurinic lyase activity, conservative amino acid cha ...19911868080
the human homologous pairing protein hpp-1 is specifically stimulated by the cognate single-stranded binding protein hrp-a.homologous pairing and strand exchange of dna are catalyzed by the human homologous pairing protein hpp-1 in a magnesium-dependent, atp-independent reaction that requires homologous dna substrates and stoichiometric quantities of hpp-1. here we show that the addition of the purified human single-strand binding (ssb) protein hrp-a to the reaction mixture stimulates the rate of homologous pairing 70-fold and reduces the amount of hpp-1 required for the reaction at least 10-fold. the identification ...19911924369
phage t4 expression vector: protection from proteolysis.we have developed an efficient method for the expression of heterologous genes during infection by t4, a bacteriophage known to inhibit the proteolytic systems of escherichia coli. this system enables us to clone genes in a plasmid expression vector and move them readily into t4. we have used lacz as a reporter gene to show that both plasmid and phage exhibit low basal expression or high-level expression under the control of a t7 promoter. this system promises a possible solution to the problem ...19911937029
cleavage reaction of a synthetic oligoribonucleotide corresponding to the autocleavage site of a precursor rna from bacteriophage t4.a fragment (guuucguacaaac) having a consensus sequence for the self-cleavage domain in a precursor of an rna molecule from t4-infected escherichia coli cells (p2sp1; precursor of species 1) was chemically synthesized and found to be cleaved either between ca (139-140) or between ua (137-138) in the presence of monovalent cations and a non-ionic detergent. the cleaved products had 5'-hydroxyl and 3'-phosphate groups, of which some were in the form 2',3'-cyclic phosphates.19911959662
lanthanide accumulation in the periplasmic space of escherichia coli b.treatment of growing escherichia coli b with lanthanide ions [lanthanum(iii), terbium(iii), and europium(iii)] and subsequent aldehyde-oso4 fixation caused areas of high contrast to appear within the periplasm (the space between inner and outer membrane of the cell envelope). x-ray microanalysis of ultrathin sections of epon-embedded or acrylic resin-embedded cells revealed the presence of the lanthanide and of phosphorus in the areas, whose contrast greatly exceeded that of other stained struct ...19911987113
effects of mutations of the bulged nucleotide in the conserved p7 pairing element of the phage t4 td intron on ribozyme function.the p7 element of group i introns contains a semiconserved "bulged" nucleotide, a c in group ia introns (nt 870 in the td intron) and an a in group ib introns [cech, t.r. (1988) gene 73, 259-271]. variants u870, g870, and a870, isolated by a combination of in vitro and in vivo genetic strategies, indicate that c and a at position 870 are consistent with splicing whereas u and g are not. although mutants g870 and u870 could be activated in vitro by increasing the mg2+ concentration, their km for ...19912009267
physiological, morphological, and physicochemical characterization of a novel escherichia coli bacteriophage, phage mm.a double-stranded dna containing, t even-like, escherichia coli bacteriophage, called mm, has been isolated from the local sewage and purified by polyethylene glycol precipitation followed by banding on a cesium chloride three-step gradient. it yields a burst size of 75 particles per infected cell, and has an adsorption coefficient of 3.3 x 10(-10) cm3/min and a latent period of 45 min. electron microscopy of phage mm reveals an isometric icosahedral head, 92 nm long and 81 nm wide, and a 112-nm ...19912059549
recombination hotspots in bacteriophage t4 are dependent on replication origins.bacteriophage t4 recombination "hotspots" were first detected by the rescue of genetic markers from uv-irradiated phage particles. these hotspots have since been detected following treatments that yield other forms of dna damage, and at least one is active in the absence of damage. the previous mapping of phage replication origins near the peaks of two recombination hotspots suggested that the origins cause the localized enhancement of recombination. here we show that deletion of one origin elim ...19912068082
a proposed structure of bacteriophage t4 gene product 22--a major prohead scaffolding core protein.gene 22 of bacteriophage t4 encodes a major prohead scaffolding core protein of 269 amino acid residues. from its nucleotide sequence the gene product (gp) 22 has a predicted mr of 29.9 and a pi of 4.3. the protein is rich in charged residues (glutamic acid and lysine) and contains low amounts of proline and glycine and no cysteine residues. we suggest that gp22 undergoes limited proteolytic processing which eliminates the short c-terminal piece from the molecule during the early steps of prohea ...19902088448
a self-splicing group i intron in the dna polymerase gene of bacillus subtilis bacteriophage spo1.we report a self-splicing intron in bacteriophage spo1, whose host is the gram-positive bacillus subtilis. the intron contains all the conserved features of primary sequence and secondary structure previously described for the group ia introns of eukaryotic organelles and the gram-negative bacteriophage t4. the spo1 intron contains an open reading frame of 522 nucleotides. as in the t4 introns, this open reading frame begins in a region that is looped out of the secondary structure, but ends in ...19902119891
the uvsy protein of bacteriophage t4 modulates recombination-dependent dna synthesis in vitro.an in vitro system containing the t4 gene 43, 45, 44/62, 32, dda, and uvsx proteins catalyzes dna synthesis that is dependent on the synapsis step of homologous genetic recombination. the rate of dna synthesis in this system is highly dependent on the concentration of the uvsx recombinase (a reca-like protein). here we report the effect of the t4 uvsy protein, a recombination accessory protein, on this reaction. low concentrations of uvsy protein greatly stimulate dna synthesis at low concentrat ...19902144282
effects of the bacteriophage t4 gene 41 and gene 32 proteins on rna primer synthesis: coupling of leading- and lagging-strand dna synthesis at a replication fork.we have demonstrated previously that the template sequences 5'-gtt-3' and 5'-gct-3' serve as necessary and sufficient signals for the initiation of new dna chains that start with pentaribonucleotide primers of sequence pppapcpnpnpn or pppgpcpnpnpn, respectively. normally, the complete t4 primosome, consisting of the t4 gene 41 (dna helicase) and gene 61 (primase) proteins, is required to produce rna primers. however, a high concentration of the 61 protein alone can prime dna chain starts from th ...19902158814
sequence analysis of conserved rega and variable orf43.1 genes in t4-like bacteriophages.bacteriophage t4 rega protein is a translational repressor of several phage mrnas. in the t4-related phages examined, rega nucleotide sequences are highly conserved and the inferred amino acid sequences are identical. the exceptional phage, rb69, did not produce a rega protein reproducibly identifiable by western blots (immunoblots) nor did it produce mrna that hybridized to t4 rega primers. nucleotide sequences of either 223 or 250 base pairs were identified immediately 3' to rega in rb18 and r ...19902168375
electron microscopic analysis of dna forks generated by escherichia coli dna helicase ii.t7 phage dna eroded with lambda exonuclease (to create 3'-protruding strands) or exonuclease iii (to create 5'-protruding strands) was treated under unwinding assay conditions with dna helicase ii. single-stranded dna-binding protein (of escherichia coli or phage t4) was added to disentangle the denatured dna and the complexes were examined in the electron microscope. dna helicase ii complexes filtered through a gel column before assay retain the ability to generate forks suggesting that dna hel ...19902170129
acute endotoxin-induced lymphocyte subset sequestration in sheep lungs.endotoxemia is associated with an early phase of pulmonary hypertension and a later increase in microvascular permeability. these physiologic changes are attended by peripheral blood and lung lymph leukopenia and a rapid accumulation of both granulocytes and lymphocytes in the peripheral lung. in the present study, the numbers of lymphocytes in blood, lung lymph, and lung tissue after infusion of endotoxin were determined by fluorescent labeling of lymphocyte populations with monoclonal antibodi ...19902179624
selenomethionyl proteins produced for analysis by multiwavelength anomalous diffraction (mad): a vehicle for direct determination of three-dimensional structure.an expression system has been established for the incorporation of selenomethionine into recombinant proteins produced from plasmids in escherichia coli. replacement of methionine by selenomethionine is demonstrated at the level of 100% for both t4 and e. coli thioredoxins. the natural recombinant proteins and the selenomethionyl variants of both thioredoxins crystallize isomorphously. anomalous scattering factors were deduced from synchrotron x-ray absorption measurements of crystals of the sel ...19902184035
stable albicidin resistance in escherichia coli involves an altered outer-membrane nucleoside uptake system.albicidin blocked dna synthesis in intact cells of a pola- enda- escherichia coli strain, and in permeabilized cells supplied with all necessary precursor nucleotides, indicating a direct effect on prokaryote dna replication. replication of phages t4 and t7 was also blocked by albicidin in albicidin-sensitive (albs) but not in albicidin-resistant (albr) e. coli host-cells. all stable spontaneous albr mutants of e. coli simultaneously became resistant to phage t6. the locus determining albicidin ...19902191080
resolution of holliday junction analogs by t4 endonuclease vii can be directed by substrate structure.endonuclease vii is an enzyme from bacteriophage t4 capable of resolving four-arm holliday junction intermediates in recombination. since natural holliday junctions have homologous (2-fold) sequence symmetry, they can branch migrate, creating a population of substrates that have the branch point at different sites. we have explored the substrate requirements of endonuclease vii by using immobile analogs of holliday junctions that lack this homology, thereby situating the branch point at a fixed ...19902199447
dna polymerase ii is encoded by the dna damage-inducible dina gene of escherichia coli.the structural gene for dna polymerase ii was cloned by using a synthetic inosine-containing oligonucleotide probe corresponding to 11 amino acids, which were determined by sequencing the amino terminus of the purified protein. the labeled oligonucleotide hybridized specifically to the lambda clone 7h9 from the kohara collection as well as to plasmid pgw511 containing the sos-regulated dina gene. approximately 1400 base pairs of dina sequence were determined. the predicted amino-terminal sequenc ...19902217198
mechanistic studies of ionizing radiation and oxidative mutagenesis: genetic effects of a single 8-hydroxyguanine (7-hydro-8-oxoguanine) residue inserted at a unique site in a viral genome.t4 rna ligase was used to construct a deoxypentanucleotide containing a single 8-hydroxyguanine (7-hydro-8-oxoguanine; g8-oh) residue, which is one of the putatively mutagenic dna adducts produced by oxidants and ionizing radiation. the pentamer d(gctag8-oh)p was prepared by the ligation of a chemically synthesized acceptor molecule, d(gcta), to an adducted donor, 8-hydroxy-2'-deoxyguanosine 5',3'-bisphosphate. the acceptor was efficiently converted to the reaction product (greater than 95%), an ...19902223758
bacteriophage t4 nrda and nrdb genes, encoding ribonucleotide reductase, are expressed both separately and coordinately: characterization of the nrdb promoter.we examined the expression of the bacteriophage t4 nrda and nrdb genes, which encode the alpha 2 and beta 2 subunits, respectively, of ribonucleoside diphosphate reductase, the first committed enzyme in the pathway of synthesis of the deoxyribonucleoside triphosphates. t4 nrda, located 700 bp upstream from nrdb, has been shown previously to be transcribed by two major transcripts: a prereplicative, polycistronic message, tu, orginating at an immediate-early promoter, pe, that is 3.5 kb upstream ...19902228963
comparison of chemical reactivity, cytotoxicity, interstrand cross-linking and dna sequence specificity of bis(platinum) complexes containing monodentate or bidentate coordination spheres with their monomeric analogues.the properties of a new bis(platinum) complex containing two monodentate coordination spheres, [(trans-ptcl(nh3)2)2h2n(ch2)4nh2]cl2 (1,1/t,t), are reported. comparison is made with respect to chemical reactivity, in vitro biological activity in murine and tumor cells, dna conformational changes, cross-linking efficiency, and sequence specificity between this complex and the previously reported complex containing two bidentate platinum atoms, [(pt(mal)(nh3))2h2n(ch2)4nh2] (2,2/c,c), as well as wi ...19902271599
selection for lysis inhibition in bacteriophage.for escherichia coli cells that have been infected by t-even bacteriophages (phages t2, t4, and t6), the adsorption of a second t-even phage results in an increase in the length of the original phage infection and an associated increase in the number of phages produced by the same infected cell. this is a phage encoded response called lysis inhibition. in this study the ecological significance of lysis inhibition is explored. in particular it is argued that lysis inhibition is an adaptive respon ...19902273898
intracellular lytic enzyme systems and their use for disruption of escherichia coli.this article focusses on lytic enzyme systems available in e. coli and their potential use for cellular disruption. in the systems described here the genetic information for lysis would be carried within the microbial host, either integrated or naturally occurring on chromosomal dna, or on extrachromosomal elements such as plasmids. each microbe would carry complete information for endogenous enzymatic lysis, and lysis would occur in a controlled manner after being triggered by an external facto ...19902291440
the influence of a double-stranded hindrance on dna synthesis performed by dna polymerase alpha, t4 dna polymerase, dna polymerase i (klenow fragment) and amv reverse transcriptase.the influence of a double-stranded region on dna synthesis performed by a series of dna polymerases on a single-stranded template was studied. two types of double-stranded hindrances were employed: a stable hairpin formed by the template alone and a region formed by the template and an extraneous oligonucleotide complementary to the template. while t4 and calf thymus alpha dna polymerases are strongly arrested at the beginning of either of the two double-stranded hindrances, the klenow fragment ...19882449362
dependence of m1 rna substrate specificity on magnesium ion concentration.we have constructed a plasmid expressing e. coli m1 rna, the catalytic rna subunit of ribonuclease p, under the control of a phage t7 promoter. the active m1 rna species synthesized in vitro by t7 rna polymerase from this vector was reacted with the trna(gln) - trna(leu) precursor rna (band k) encoded by phage t4. only the trna(leu) moiety of this dimeric precursor rna contains the 3' terminal c-c-a sequence common to all trnas. we observed that protein-free m1 rna was capable of processing the ...19882453026
symmetric transcription of bacteriophage t4 base plate genes.dot-blot and northern-blot experiments, using strand-specific rna probes, show that part of the bacteriophage t4 dna that codes for six of the base plate structural genes (gp 51, 27, 28, 29, 48 and 54), is transcribed in vivo from both dna strands. the r dna strand transcripts contain sequences which are translated into structural proteins. antisense l strand rna is about 100 fold less abundant than rna molecules transcribed from the r dna strand.19882468563
single amino acid changes that alter the dna sequence specificity of the dna-[n6-adenine] methyltransferase (dam) of bacteriophage t4.bacteriophage t4 codes for a dna-[n6-adenine] methyltransferase (dam) which recognizes primarily the sequence gatc in both cytosine- and hydroxymethylcytosine-containing dna. hypermethylating mutants, damh, exhibit a relaxation in sequence specificity, that is, they are readily able to methylate non-canonical sites. we have determined that the damh mutation produces a single amino acid change (pro126 to ser126) in a region of homology (iii) shared by three dna-adenine methyltransferases; viz, t4 ...19892510127
impaired expression of certain prereplicative bacteriophage t4 genes explains impaired t4 dna synthesis in escherichia coli rho (nusd) mutants.the escherichia coli rho 026 mutation that alters the transcription termination protein rho prevents growth of wild-type bacteriophage t4. among the consequences of this mutation are delayed and reduced t4 dna replication. we show that these defects can be explained by defective synthesis of certain t4 replication-recombination proteins. expression of t4 gene 41 (dna helicase/primase) is drastically reduced, and expression of t4 genes 43 (dna polymerase), 30 (dna ligase), 46 (recombination nucle ...19892544560
superhelical stress restrained in plasmid dna during repair synthesis initiated by the uvra, b and c proteins in vitro.purified uvra, uvrb, uvrc, uvrd, pola and lig proteins from escherichia coli have been used to assess the effect of nucleotide excision repair on the conformation of native negatively supercoiled plasmid dna in an in vitro test system. the analysis of labeled reaction products on specific gel systems suggests that the uvr excinuclease has the ability to restrain the superhelical stress in the template dna during the repair process. this feature, observed in the case of the uvr system is not foun ...19892557590
a simple and versatile method for the preparation of vector-primers by adapter-end-primer ligation.a group of efficient cdna cloning strategies employs vector-primers where cdna synthesis starts from the oligo(dt)-primer tail, which is conventionally attached to cloning vectors by use of terminal deoxynucleotidyl transferase. an alternative, efficient and more versatile method of vector-primer preparation is to directly ligate, by use of t4 dna ligase, a double-digested vector, e.g., ptz18r/pst i/bam hi, to a synthetic (bam hi)-adapter-end-primer, 5'-pgatcc-tn or 5'-pgatcc-site-specific seque ...19892561065
rna splicing in prokaryotes: bacteriophage t4 leads the way. 19852580641
preparation of 2-azidoadenosine 3',5'-[5'-32p]bisphosphate for incorporation into transfer rna. photoaffinity labeling of escherichia coli ribosomes.2-azidoadenosine was synthesized from 2-chloroadenosine by sequential reaction with hydrazine and nitrous acid and then bisphosphorylated with pyrophosphoryl chloride to form 2-azidoadenosine 3',5'-bisphosphate. the bisphosphate was labeled in the 5'-position using the exchange reaction catalyzed by t4 polynucleotide kinase in the presence of [gamma-32p]atp. polynucleotide kinase from a t4 mutant which lacks 3'-phosphatase activity (atp:5'-dephosphopolynucleotide 5'-phosphotransferase, ec 2.7.1. ...19892647526
[effect of he-ne laser radiation on the bacteriophage t4-escherichia coli system].exposure of t4 bacteriophage, having no red light chromophores, to he-ne laser (lambda = 632.8 nm) of 10(3)-6 x 10(4) j/m2 does not influence its lytic properties. irradiation of e. coli wp2 bacteria with doses of 4-6 x 10(3) j/m2 causes a 1.25-1.35-fold increase in their ability to keep on the development of nonirradiated bacteriophage t4.19892654997
nucleotide sequences of bacteriophage t4 genes 13, 14 and 15. 19892657662
transcript analyses of the uvsx-40-41 region of bacteriophage t4. changes in the rna as infection proceeds.the bacteriophage t4 genes uvsx (recombination protein), 40 (stimulates head formation), and 41 (dna replication protein, part of the primase-helicase) are located together on the t4 genome (5'----3' uvsx-40-41). previous analyses have indicated that all three proteins are expressed within 5 min after infection and that the level of 41 protein is less than that of uvsx. the mapping of transcripts from this region (reported here) shows that this expression arises from polycistronic messages detec ...19892668289
locations of amino acid substitutions in bacteriophage t4 tsl56 dna polymerase predict an n-terminal exonuclease domain.the amino acid substitutions responsible for the temperature-sensitive (ts) and mutator phenotypes of the classical bacteriophage t4 dna polymerase mutant tsl56 were determined. tsl56 dna polymerase has two mutations in the 5' end of the dna polymerase gene (g43) that produce two amino acid substitutions: codon 89, alanine to threonine, and codon 363, aspartate to asparagine. both mutations are required for the strong ts and mutator phenotypes. the increased error rate of the tsl56 dna polymeras ...19892677403
site-specific mutagenesis of t4 gene 32: the role of tyrosine residues in protein-nucleic acid interactions.bacteriophage t4 gene 32 encodes a single-stranded dna (ssdna) binding protein (gp32) required for t4 dna replication, recombination, and repair. previous physicochemical studies on gp32 and other ssdna binding proteins have suggested that binding may involve hydrophobic interactions that result from the close approach of several aromatic amino acid side chains with the nucleic acid bases. in the case of gp32, five tyrosines and two phenylalanines have previously been implicated in gp32.ssdna co ...19892684276
evidence for a net-like organization of lipopolysaccharide particles in the escherichia coli outer membrane.cell wall lps of escherichia coli are organized as particles which are visible in the electron microscope, after treatment of the wall with alkali. we now describe alkali treated walls of three e. coli strains with differences in susceptibility to the t4 phage infection. strain cr63, a usual host for the t4 phage, shows the lps particles on the murein layer. these particles are absent in alkali treated cell walls of the strain w. walls of this strain are broken during t4 infection and phages can ...19892689280
site-directed mutagenesis of the t4 endonuclease v gene: mutations which enhance enzyme specific activity at low salt concentrations.previous structure/function analyses of the dna repair enzyme, t4 endonuclease v, have suggested that the extreme carboxyl portion of the enzyme is associated with pyrimidine dimer-specific binding (recinos and lloyd, and stump and lloyd, biochemistry 27:1832-1838 and 1839-1843, 1988, respectively). within the final 11 amino acids there are 5 aromatic, 2 basic, and no acidic residues and it has been proposed that these residues stack with and electrostatically interact with the kinked dna at the ...19892695926
monofunctional angular furocoumarins: sequence specificity in dna photobinding of 6,4,4'-trimethylangelicin and other angelicins.the sequence specificity in the photoreaction (365 nm) of 6,4,4'-trimethylangelicin (tma) with dna fragments of the lac i gene of escherichia coli was studied by using dna sequencing methodology. in order to map the sites of tma photoaddition, we took advantage of the (3'-5') exonuclease activity associated with t4 dna polymerase, which is blocked by bulky adducts, such as furocoumarin photoadducts. a quantitative analysis of the sites of photoaddition is reported. tma was demonstrated to photor ...19892762383
bacteriophage t4 early promoter regions. consensus sequences of promoters and ribosome-binding sites.twenty-nine early promoters from bacteriophage t4 and 14 early promoters from bacteriophage t6 were isolated using vector m13hdl17, a promoterless derivative of m13mp8 carrying a linker sequence, the bacteriophage lambda-terminator tr1, and the lacz' gene including part of its ribosome-binding site. the consensus sequence for the t4 promoters is: (sequence; see text). ribosome-binding sites of t4 share the sequence: 5'...g.ggaga..aa.atgaa.a...3' the consensus sequence of the t4 early promoter re ...19892810355
dna synthesis is blocked by cigarette tar-induced dna single-strand breaks.dna single-strand breaks are caused by aqueous extracts of cigarette tar, due to the reduction of oxygen to superoxide by tar and the subsequent production of hydroxyl radicals. the action of dna metabolism enzymes on these single-strand breaks has been studied to probe the consequences of these lesions for dna repair. our results demonstrate that cigarette tar-induced nicks are blocked at the 3' terminus since they are totally incapable of activating dna for dna synthesis by escherichia coli dn ...19872820603
sequence effect on alkali-sensitive sites in uv-irradiated sv40 dna.ultraviolet light at 254 nm induces various kinds of dna damage. we have located and quantified the pyrimidine (6-4) pyrimidone photoproducts along three hundred and forty two nucleotides of sv40 dna. the level of photoproduct induction varies greatly according to the position on the dna, but unlike what happens with pyrimidine dimers, the very adjacent nucleotides do not play a major role in the frequency of formation. a new alkali-sensitive site has been found on the aca sequence after uv irra ...19872825122
molecular cloning and characterization of the gene encoding cholinephosphate cytidylyltransferase in saccharomyces cerevisiae.1. the structural gene for cholinephosphate cytidylyltransferase (cct) was isolated from a saccharomyces cerevisiae genomic library by means of complementation in a mutant of the yeast defective in the enzyme. the cloned dna restored both the growth and cholinephosphate cytidylyltransferase activity of the mutant. whereas the enzyme of the mutant was thermolabile, the enzyme produced by the transformant was indistinguishable in heat stability from that produced by the wild type. 2. strains carry ...19872826147
illegitimate recombination mediated by calf thymus dna topoisomerase ii in vitro.we have found that purified calf thymus dna topoisomerase ii mediates recombination between two phage lambda dna molecules in an in vitro system. the enzyme mainly produced a linear monomer recombinant dna that can be packaged in vitro. novobiocin and anti-calf thymus dna topoisomerase ii antibody inhibit this atp-dependent recombination. the recombinant molecules contain duplications or deletions, and most crossovers take place between nonhomologous sequences of lambda dna, as judged by the seq ...19882832845
general method for quantifying base adducts in specific mammalian genes.a general method has been developed to measure the formation and removal of dna adducts in defined sequences of mammalian genomes. adducted genomic dna is digested with an appropriate restriction enzyme, treated with escherichia coli uvrabc excision nuclease (abc excinuclease), subjected to alkaline gel electrophoresis, and probed for specific sequences by southern hybridization. the abc excinuclease incises dna containing bulky adducts and thus reduces the intensity of the full-length fragments ...19882836856
a family of autocatalytic group i introns in bacteriophage t4. 19872841063
enzyme binding-inhibiting assay for iodothyronine 5'-monodeiodinase (5'-md) and its application to isolation of complementary deoxyribonucleic acid clones for the 5'-md in rat liver.to identify and/or quantify type i t4 5'-monodeiodinase (5'-md) immunologically, polyclonal antibodies were produced by immunization of rabbits with solubilized microsomal proteins (smp) from rat liver. pilot studies showed that the antibody binds to, but does not neutralize, rat liver enzyme. we have employed the polyclonal antibody to develop a 5'-md enzyme binding-inhibiting assay (mbia). for this purpose, active, inactive, or synthetic 5'-md was preincubated with rabbit antibody and removed ...19882841089
dna polymerase alpha activity is not affected by protein kinases or alkaline phosphatase.recent studies with crude or partially purified cell extracts have suggested that dna polymerase alpha activity may be regulated by enzymatic phosphorylation. to further investigate these findings, we have examined the effects of protein kinases and phosphatases on highly purified dna polymerase alpha from mouse cells. incubation of dna polymerase alpha with a variety of protein kinases, including protein kinase c, had no effect on polymerase activity. in addition, treatment of the polymerase wi ...19892930569
purification and characterization of the t4 bacteriophage uvsx protein.gene uvsx of bacteriophage t4 encodes a 40,000-dalton protein that plays a key role in the major pathway for genetic recombination in t4-infected cells. mutations at the uvsx locus lead to increased sensitivity to various dna-damaging agents, reduced phage bursts, decreased genetic recombination, and early arrest of dna synthesis. like the escherichia coli reca protein, the purified uvsx protein is a dna-dependent atpase that catalyzes pairing between homologous single- and double-stranded dna m ...19862939071
selective inhibition of escherichia coli recbc activities by plasmid-encoded gams function of phage lambda.the gam locus of bacteriophage lambda encompasses two coding sequences with the same reading frame and translational stop, one corresponding to an mr 11646 polypeptide (gams gene), the other to an mr 16349 polypeptide (gaml gene). a dna segment encoding gams but not gaml was placed under lambda pr promoter control (regulated by the cits857-coded repressor) on a multicopy plasmid, and an insertion mutation (gams201) was constructed. expression of gams+, but not gams201, inhibited escherichia coli ...19862943636
[transmission of amber mutants of bacteriophage t4. iii. thermostability of the replication of amber mutants in cells of a non-permissive host is typical for the majority of phage tail genes].the article deals with determination of the spreading of the earlier discovered phenomenon of the temperature sensitivity of multiplication of t4 phage amber mutants. on the basis of the study of the dependence of multiplication of 50 amber mutants in 22 genes of t4 phage tail in the cells of non-permissive host on the incubation temperature in the range of 15-41 degrees c, the following conclusion is drawn: temperature sensitivity of multiplication of amber mutants appears to be gene-specific a ...19872953651
receptor-recognizing proteins of t-even type bacteriophages. constant and hypervariable regions and an unusual case of evolution.proteins 38 of bacteriophages t2, k3, ox2 and m1 are located at the free ends of their long tail fibers and function as adhesins, i.e. they mediate binding to the bacterial receptors. the latter three phages use the escherichia coli outer membrane protein ompa as a receptor, while t2 uses the outer membrane proteins ompf or ttr. the dna sequences of genes 38 of phages ox2 and m1 have been determined and are compared with those known for t2 and k3. the genes encode 262(t2), 260(k3), 266(ox2) and ...19872958637
inhibition of streptomycin-dependent mutation in escherichia coli on the lytic growth of bacteriophage lambda.spontaneous streptomycin-dependent mutants (strda) were isolated from escherichia coli c600. on c600 strd, the lytic growth of phage lambda nam and lambda ci857 was inhibited. after e. coli lysogenic strain 1.1485 (lambda ci857) mutated to strda, induction of lambda was decreased greatly. on strda of e. coli strains c600 and 1.1485 (lambda ci857), the plating efficiencies and burst sizes of phage t4 and t7 remained normal. since strda is a mutation in the structural gene for ribosomal protein s1 ...19872960017
induction of helper and suppressor t cells by nonoverlapping determinants on the large protein antigen, beta-galactosidase.the fine specificity of the t cell repertoire directed against t helper (th)-inducing and t suppressor (ts)-inducing determinants was examined with cyanogen bromide and tryptic peptides of escherichia coli beta-galactosidase (gz), a large tetrameric protein (monomer molecular weight = 116 kda). immunization with cyanogen bromide fragment 2 [cb-2, amino acids (a.a.) 3-92] induced both specific th and ts cells. study of the induction of these functionally opposite t cell subpopulations with trypti ...19882963778
the mechanism of homologous dna strand exchange catalyzed by the bacteriophage t4 uvsx and gene 32 proteins.a strand exchange reaction between a single-stranded dna circle and a homologous linear double-stranded dna molecule is catalyzed by a mixture of two t4 bacteriophage proteins, the uvsx protein (a dna-dependent atpase that resembles the reca protein) and the gene 32 protein (a helix-destabilizing protein). the products are different from those formed in the corresponding reca protein-catalyzed reaction; rather than producing a linear single strand plus a nicked circular double-stranded (form ii) ...19882967823
release of respiratory control in escherichia coli after bacteriophage adsorption: process independent of dna injection.adsorption of phages t4, t5, and bf23 to previously starved escherichia coli cells triggered the immediate release of respiratory control. a similar stimulation of respiration was induced after t4 ghost attachment, showing that this process was independent of the mechanism of dna injection. rather, this change in the respiratory rate was related to the transient depolarization of the cytoplasmic membrane also induced after phage and ghost adsorption. both processes were suppressed by addition of ...19852981800
the dna restriction endonuclease of escherichia coli b. ii. further studies of the structure of dna intermediates and products.the dna intermediates and final products formed by the type i restriction endonuclease, ecob, were further characterized. dna cleaved on only one strand (hemi-restricted dna) contains gaps of approximately 70-100 nucleotides, while the fully restricted products contain 3'-single-stranded tails averaging approximately 70-100 nucleotides for each strand cleaved. the gaps and tails are formed with the release of an equal number of nucleotides as small oligonucleotides that are soluble in acid. afte ...19852985610
molecular cloning and physical mapping of the genome of fish lymphocystis disease virus.a defined and complete gene library of the fish lymphocystis disease virus (fldv) genome was established. fldv dna was cleaved with ecori, bamhi, ecori/bamhi and ecori/hindiii and the resulting fragments were inserted into the corresponding sites of the pacyc184 or pat153 plasmid vectors using t4 dna ligase. since fldv dna is highly methylated at cpg sequences (darai et al., 1983; wagner et al., 1985), an escherichia coli gc-3 strain was required to amplify the recombinant plasmids harboring the ...19852996221
t4-induced alpha- and beta-glucosyltransferase: cloning of the genes and a comparison of their products based on sequencing data.bacteriophage t4 alpha- and beta-glucosyltransferases link glucosyl units to the 5-hmdc residues of its dna. the monoglucosyl group in alpha-linkage predominates over the one in beta linkage. having recently reported on the nucleotide sequence of gene alpha gt (1) we now determined the nucleotide sequence of gene beta gt. the genes were each cloned on a high expression vector under the control of the lambda pl promoter. after thermo-induction the proteins were isolated and purified to homogeneit ...19852999696
half-site editing: an in vitro mutagenesis procedure for truncating a dna fragment and introducing a new restriction site.half-site editing is an in vitro mutagenesis procedure designed for use in making precise plasmid constructions. like many in vitro mutagenesis techniques, this procedure involves hybridization of a mutagenic oligonucleotide primer to single-stranded template dna followed by polymerization with dna polymerase i (klenow). half-site editing differs from other techniques in two main ways. first, t4 dna polymerase treatment truncates the target dna at a point determined by the primer and repairs any ...19863006543
microinjection of escherichia coli uvra, b, c and d proteins into fibroblasts of xeroderma pigmentosum complementation groups a and c does not result in restoration of uv-induced unscheduled dna synthesis.the uv-induced unscheduled dna synthesis (uds) in cultured human fibroblasts of repair-deficient xeroderma pigmentosum complementation groups a and c was assayed after injection of identical activities of either uvr excinuclease (uvra, b, c and d) from escherichia coli or endonuclease v from phage t4. under conditions where the t4 enzyme was able to induce repair synthesis in both xp complementation groups in agreement with earlier observations (de jonge et al., 1985), no effect of the uvrabcd e ...19863014326
a specific model for the conformation of single-stranded polynucleotides in complex with the helix-destabilizing protein gp32 of bacteriophage t4. 19863017469
a plasmid expression vector that permits stabilization of both mrnas and proteins encoded by the cloned genes.two new expression vectors have been constructed to take advantage of several useful properties of bacteriophage t4-infected escherichia coli. these plasmids, prdb8 and prdb9, contain the promoter region and start codon of t4 gene 32, a contiguous multiple cloning site (mcs), and translation and transcription termination signals. dna fragments inserted into the mcs are transcribed and translated at a high level in both uninfected and phage t4-infected cells. furthermore, the extreme stability of ...19863026907
[plasmid vectors of "insertion inactivation" of the trimethoprim resistance marker].we demonstrate the possibility of using the t4 phage frd gene as an insertion inactivation marker within pbr322, in plasmids with changing copy number and expression of foreign genes under control. the structural part of the frd genes contains unique recognition sites for ecori and sali endonucleases. transformants with recombinant plasmids carrying the frd gene grow on media with up to 500 mkg/ml trimethoprim, whatever the gene dosage.19873032740
use of a phage vector for rapid synthesis and cloning of single-stranded cdna.we have developed a technique for synthesis of single stranded complementary dna (ss cdna) using specifically designed phage ssdna as vector primer. this vector (ppbs27) was constructed by introducing a poly(dt) tail adjacent to the xbai site of ptz18r, which can exist either as a plasmid in escherichia coli or as a ssdna phage. the ppbs27 phage vector is linearized with xbai using a restriction-site-directed fragment and used to anneal a mixture of poly(a) + rna for cdna synthesis by reverse tr ...19873036656
yeast gene rad52 can substitute for phage t4 gene 46 or 47 in carrying out recombination and dna repair.the rad52 gene of saccharomyces cerevisiae and genes 46 and 47 of bacteriophage t4 are essential for most recombination and recombinational repair in their respective organisms. the rad52 gene was introduced into expression vectors that were used to transform escherichia coli. the expression of rad52 was then induced, and the ability of rad52 to complement phage mutants defective in gene 46 or 47 was determined with respect to the three criteria of phage growth, recombination, and recombinationa ...19883045825
in vitro and in vivo recombination-related reactions of escherichia coli reca protein and glucosyl-hydroxymethyl-deoxycytidine dna.recombination of t4 phage is not controlled by the host reca gene but by an analogous phage gene, uvsx. we have tested the hypothesis that reca protein is inactive in t4-infected cells because it is unable to catalyze reactions involving single stranded dna containing glucosyl-hydroxylmethyl-deoxycytidine. we found, however, that with modified and unmodified deoxycytidine containing dnas, uvsx protein and reca protein catalyze in vitro reactions related to dna recombination, but in t4-infected c ...19883054489
dna polymerase of bacteriophage t4 is an autogenous translational repressor.in bacteriophage t4 the protein product of gene 43 (gp43) is a multifunctional dna polymerase that is essential for replication of the phage genome. the protein harbors dna-binding, deoxyribonucleotide-binding, dna-synthesizing (polymerase) and 3'-exonucleolytic (editing) activities as well as a capacity to interact with several other t4-induced replication enzymes. in addition, the t4 gp43 is a repressor of its own synthesis in vivo. we show here that this protein is an autogenous repressor of ...19883054876
mischarging escherichia coli trnaphe with l-4'-[3-(trifluoromethyl)-3h-diazirin-3-yl]phenylalanine, a photoactivatable analogue of phenylalanine.the boc-protected derivative of a photoactivatable, carbene-generating analogue of phenylalanine, l-4'-[3-(trifluoromethyl)-3h-diazirin-3-yl]phenylalanine [(tmd)phe], was used to acylate 5'-o-phosphorylcytidylyl(3'-5')adenosine (pcpa). a diacyl species was isolated which upon successive treatments with trifluoroacetic acid and 0.01 m hcl yielded a 1:1 mixture of 2'(3')-o-(tmd)phenylalanyl-pcpa and of its 2'-5'-phosphodiester isomeric form. adapting a procedure introduced by hecht's group [heckle ...19883061465
bacteriophage t4 dna polymerase determines the amount and specificity of ultraviolet mutagenesis.ultraviolet mutagenesis in bacteriophage t4 proceeds via error-prone repair (epr) and requires the functional integrity of the uvswxy system which mediates genetic recombination, recombinational repair, and mutability by diverse dna damaging agents. current opinion holds that mutagens acting through epr generate dna damage which blocks the progress of the replication complex and that epr consists of the facilitated bypass of such inaccurate, damaged templates. this notion predicts that the t4 dn ...19883063950
structural and functional relationships between prokaryotic and eukaryotic dna polymerases.the bacillus subtilis phage luminal diameter 29 dna polymerase, involved in protein-primed viral dna replication, was inhibited by phosphonoacetic acid (paa), a known inhibitor of alpha-like dna polymerases, by decreasing the rate of elongation. three highly conserved regions of amino acid homology, found in several viral alpha-like dna polymerases and in the luminal diameter 29 dna polymerase, one of them proposed to be the paa binding site, were also found in the t4 dna polymerase. this prokar ...19873127204
site-directed mutagenesis of the t4 endonuclease v gene: role of lysine-130.the dna sequence of the bacteriophage t4 denv gene which encodes the dna repair enzyme endonuclease v was previously constructed behind the hybrid lambda promoter olpr in a plasmid vector. the olpr-denv sequence was subcloned in m13mp18 and used as template to construct site-specific mutations in the denv structural gene in order to investigate structure/function relationships between the primary structure of the protein and its various dna binding and catalytic activities. the lys-130 residue o ...19883132202
amp-dependent dna relaxation catalyzed by dna ligase occurs by a nicking-closing mechanism.in the presence of amp and mg2+, a covalently closed duplex dna containing negative superhelical turns was treated with dna ligase isolated from bacteriophage t4-infected e. coli. this resulted in the gradual and not sudden loss of superhelical turns as for example in the case of type i dna topoisomerase. all dna products remain covalently closed. since t4 enzyme-mediated dna relaxation is inhibited by both pyrophosphate and by atp this suggests that dna relaxing and dna joining activities proba ...19883137526
a possible effect of heme on the fate of dna ligase activity extracted from differentiating mouse erythroleukemia cells.when mouse erythroleukemia (mel) cells were induced to differentiate by growth in the presence of dimethyl sulfoxide, hexamethylene bisacetamide (hmba), or hemin, the apparent activity of dna ligase extractable from inducer-treated cells decreased 70 to 80% when compared to untreated cells. earlier work had indicated that these changes did not occur in a differentiation-resistant mel cell variant and suggested that the decrease in the level of dna ligase activity might be related to the differen ...19883180046
nucleotide and deduced amino acid sequence of stp: the bacteriophage t4 anticodon nuclease gene.pre-existing host trnas are reprocessed during bacteriophage t4 infection of certain escherichia coli strains. in this pathway, trnalys is cleaved 5' to the wobble base by anticodon nuclease and is later restored in polynucleotide kinase and rna ligase reactions. anticodon nuclease depends on prr, a locus found only in host strains that restrict t4 mutants lacking polynucleotide kinase and rna ligase; and on stp, the t4 suppressor of prr restriction. stp was cloned and the nucleotide sequences o ...19883280805
an in vitro assay for frameshift mutations: hotspots for deletions of 1 bp by klenow-fragment polymerase share a consensus dna sequence.the fidelity of in vitro dna synthesis catalyzed by the large fragment of dna polymerase i was examined. the templates, specifically designed to detect shifts to the +1 or to the -1 reading frame, are composites of m13mp8 and bacteriophage t4 riib dna and were designed to assist in the identification of the types of frameshifts that are the specific consequence of dna polymerization errors. in vitro polymerization by the klenow fragment produced only deletions, rather than the mixture of duplica ...19883282984
effect of ph on the base-mispairing properties of 5-bromouracil during dna synthesis.we have utilized an electrophoretic assay of misincorporation to investigate the possibility that ionization of 5-bromouracil (bu) may play a role in its mispairing during dna synthesis in vitro. we examined the effects of increasing ph on the relative rates of formation of bu.g and t.g mispairs during chain elongation catalyzed by various dna polymerases. for the klenow fragment of escherichia coli dna polymerase i, increasing ph facilitated bu.g mispair formation (relative to t.g mispairing) w ...19883284589
mutant 16s ribosomal rna: a codon-specific translational suppressor.we have isolated an unusual codon-specific translational suppressor in escherichia coli. the suppressor resulted from a spontaneous mutation in a chromosomal gene during a selection for suppressors of the auxotrophic nonsense mutation trpa(uga211). the suppressor allows readthrough of uga mutations at two positions in trpa and at two sites in bacteriophage t4. it does not, however, suppress amber (uag) or ochre (uaa) mutations that were tested in both genomes, some of which were at the same posi ...19883288986
synthesis and reactivity of intermediates formed in the t4 rna ligase reaction.the intermediate adenylated donor derivatives a(5')pp(5')dtp and a(5')pp(5')gpgpgp have been prepared from suitable phosphorylating reagents activated by 1-hydroxybenzotriazole. phosphodiester bond formation between donor and acceptor oligonucleotides as catalyzed by t4 rna ligase is shown to be more efficient when the adenylated form of the donor molecule is used.19873299268
temperature sensitivity of the multiplication of bacteriophage t4 amber mutants on nonpermissive host: characterization of the phenomenon.the existence of temperature sensitivity of the multiplication of amber mutants on a nonpermissive host has been established for a considerable number of mutants in tail and head genes and for mutants in some other t4 genes as well. temperature sensitivity of multiplication appears to be gene specific, and is typical of amber mutants in genes the products of which are not numerous per phage or which play the role of catalytic factor. moreover, in most cases temperature sensitivity is characteris ...19873310383
genetic recombination between closely linked makers of bacteriophage t4. iv. mutations which interfere with mismatch repair.t4 phage mutations mco1 and mco3 reduced recombination between multiple closely linked markers preferentially and were located between gene 24 and gene 25. the mco1 and the mco3 mutants complemented each other. the results of uv-cross reactivation experiments indicated that the mco1 and the mco3 mutants could rescue the markets of uv-damaged phage, but could not segregate them from flanking mutations. therefore, it is concluded that mco1 mutation and mco3 mutation interfere with mismatch repair.19873312727
the essential role of recombination in phage t4 growth. 19873327469
genetic delineation of functional components of the group i intron in the phage t4 td gene. 19873331339
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