nonsense suppressor mutants of bacteriophage bf23. 1978716224
clustering of transfer rna genes in bacteriophage bf23. 1978716225
membrane protein biosynthesis in bacteriophage bf23-infected escherichia coli.when escherichia coli is infected with bacteriophage bf23, two new proteins with molecular weights greater than 10,000, as indicated by polyacrylamide gel electrophoresis, are found associated with the cells' membranes. one of these, found associated with both the inner and outer membrane, has a molecular weight of about 55,000 and is regulated by the a1 gene of this phage, a gene found on the spontaneously injected 8% piece of bf23 dna, dna that codes for the synthesis of proteins necessary for ...1976785024
characterization of preearly genes in the terminal repetition of bacteriophage bf23 dna by nucleotide sequencing and restriction mapping. 19911989394
cloning and expression of the gene for the vitamin b12 receptor protein in the outer membrane of escherichia coli.the transport of cyanocobalamin (vitamin b12) in cells of escherichia coli is dependent on a receptor protein (btub protein) located in the outer membrane. a 9.1-kilobase pair bamhi fragment carrying the btub gene was cloned from a specialized transducing phage into multicopy plasmids. insertions of transposon tn1000 which prevented production of the receptor localized btub to a 2-kilobase pair region. further subcloning allowed isolation of this region as a 2.3-kilobase pair sau3a fragment. the ...19852982793
two outer membrane transport systems for vitamin b12 in salmonella typhimurium.the involvement of an outer membrane transport component for vitamin b12 uptake in salmonella typhimurium, analogous to the btub product in escherichia coli, was investigated. mutants of s. typhimurium selected for resistance to bacteriophage bf23 carried mutations at the btub locus (butbs) (formerly called bfe, at the analogous map position as the e. coli homolog) and were defective in high-affinity vitamin b12 uptake. the cloned e. coli btub gene (btube) hybridized to s. typhimurium genomic dn ...19892656634
identity of genes a2 and a3 of bacteriophage bf23.the polypeptide coded by gene a3 of bacteriophage bf23 has been purified and its n-terminal amino acid sequence determined. this sequence is identical to the n-terminal sequence of the polypeptide coded by gene a2. the two gene products have identical molecular weight. we conclude that these two gene products are identical, and are coded by one and the same gene, namely gene a2-a3, which was previously thought to be two genes, a2 and a3.19902196744
characterization of preearly genes in the terminal repetition of bacteriophage bf23 dna by nucleotide sequencing and restriction mapping.a finer restriction map of the terminal repetition of bacteriophage bf23 dna was determined and used to localize a 3.4-kbp deletion in the terminal repetition and to determine the physical location of preearly gene a2-a3. the nucleotide sequence of gene a2-a3 was determined and shown to code for a protein of 125 amino acids with no indication of a membrane transport sequence. the beginning of an adjacent gene, probably gene a1, was also sequenced.19902196743
genetic locus determining resistance to phage bf23 and colicins e 1 , e 2 and e 3 in escherichia coli. 19724561717
amino acid sequence of the bacteriophage t5 gene a2 protein.the complete amino acid sequence of the bacteriophage t5-encoded gene a2 protein was determined by protein sequencing. the 134-residue sequence is closely similar to that reported for the product of gene a2-a3 of bacteriophage bf23. segments of the sequence are similar to segments of bacteriophage t4 gene 32 protein, bacteriophage t3 rna polymerase, and the protein encoded by the host gene responsible for isoenzyme conversion of alkaline phosphatase. the similarity of residues 26-46 to a portion ...19912059212
abortive infection by bacteriophage bf23 due to the colicin ib factor. ii. involvement of pre-early proteins. 19744599380
abortive infection by bacteriophage bf23 due to the colicin ib factor. i. genetic studies of nonrestricted and amber mutants of bacteriophage bf23. 19714942554
genetic analysis of escherichia coli k12 mutants resistant to bacteriophage bf23 and the e-group colicins. 19714944012
deletions or duplications in the btub protein affect its level in the outer membrane of escherichia coli.the escherichia coli btub product is an outer membrane protein that mediates the tonb-coupled active transport of cobalamins and the uptake of the e colicins and bacteriophage bf23. the roles of various segments of the btub protein in its function or cellular localization were investigated by analysis of several genetic constructs. hybrid proteins in which various lengths from the amino terminus of btub were linked to alkaline phosphatase (btub::phoa genes) were all secreted across the cytoplasm ...19911885541
restriction of the growth of bacteriophage bf23 by a colicine i (col i-p9) factor. 19665938892
cloning, sequencing, and recombinational analysis with bacteriophage bf23 of the bacteriophage t5 oad gene encoding the receptor-binding protein.binding of bacteriophage t5 to its receptor, the escherichia coli fhua protein, is mediated by tail protein pb5. in this article we confirm that pb5 is encoded by the t5 oad gene and describe the isolation, expression, and sequencing of this gene. in order to locate oad precisely, we analyzed recombinants between bf23, a t5-related phage with a different host range, and plasmid clones containing segments of the t5 chromosome. this analysis also showed that oad has little or no homology with hrs, ...19911825083
conserved structural and regulatory regions in the salmonella typhimurium btub gene for the outer membrane vitamin b12 transport protein.the salmonella typhimurium btub gene encodes an outer membrane protein that is necessary for the transport of vitamin b12 and the uptake of the e colicins and bacteriophage bf23. the sequence of this gene showed 87% identity of the deduced polypeptide to its escherichia coli homolog, and its product was found to function in transport as effectively in cells of e. coli as did the native protein. the extensive sequence conservation within the first 300 transcribed nucleotides, which include the le ...19921448622
transport of vitamin b12 in escherichia coli: common receptor system for vitamin b12 and bacteriophage bf23 on the outer membrane of the cell envelope.we showed previously that the outer membrane of the escherichia coli cell envelope normally contains about 200 to 250 b12 receptors, and that these receptors function both in b12 transport and as receptors for the e colicins. this paper shows that this receptor system is also shared with bacteriophage bf23. a strong positive correlation was observed between the number of b12 receptors per cell and the rate of adsorption of bf23. cells from mutant strains that lacked b12 receptors did not adsorb ...19761254550
o antigen-dependent mutant of bacteriophage t5.a t5 mutant is described which showed normal infection of escherichia coli f but virtually no infection of cells lacking the e. coli f o antigen. this was due to very poor adsorption to the o antigen-deficient cells. inactivation kinetics with anti-t5 serum and adsorption and desorption kinetics to receptor-deficient e. coli f cells suggested that the mutation did not affect the l-shaped tail fibers which mediate binding to the o antigen. proof was obtained from genetic data; the structural gene ...19846361278
genes affecting coliphage bf23 and e colicin sensitivity in salmonella typhimurium.rough strains of salmonella typhimurium were sensitive to coliphage bf23. spontaneous mutants resistant to bf23 (bfe) were isolated, and the trait was mapped using phage p1. the bfe gene in s. typhimurium was located between argf (66% co-transducible) and rif (61% co-transducible). the bf23-sensitive s. typhimurium strains were not sensitive to the e colicins. cells of these rough strains absorbed colicin, as measured by loss of e2 or e3 killing units from colicin solutions and by specific adsor ...19751104583
growth of coliphage bf23 on rough strains of salmonella typhimurium: the bfe locus.coliphage bf23 develops in salmonella typhimurium rough strains. the phage is neither restricted nor modified by s. typhimurium. the growth patterns of the phage were slightly different in s. typhimurium than in escherichia coli, although phage propagated on s. typhimurium is identical to the phage propagated in e. coli by several criteria used. mutants of s. typhimurium resistant to bf23 were isolated and found to map (by p22- and pl-mediated transduction) in the same position as bfe mutants of ...1976787757
colicins e4, e5, e6 and a and properties of btub+ colicinogenic transconjugants.e colicins are those inactive on btub mutants, which lack the outer membrane protein that adsorbs vitamin b12, e colicins and phage bf23; types e1, e2, e3 and e7 have been defined by the specific immunity of e-colicinogenic strains to the type of e colicin they produce. further immunity types - e4, e5, e6 - are now described. shigella sonnei of colicin type 9 makes colicin e4, and shigella sonnei of types 9a, 12 and 14 make colicin e6 (not colicin e3, as previously supposed). many local shigella ...19827045283
physical map of bacteriophage bf23 dna: restriction enzyme analysis.cleavage maps of bacteriophage bf23 dna have been constructed for the restriction endonucleases sali (3 fragments), bamhi (5 fragments), ecori, (8 fragments), bali (13 fragments), and hpai (49 fragments, 32 of which have been ordered). the maps were determined by (i) analysis of deletion mutants, (ii) digestion with two endonucleases, (iii) digestion of isolated fragments with a second enzyme, (iv) analysis of partial digests, and (v) digestion after treatment with lambda exonuclease.1979480473
terminally redundant deletion mutants of bacteriophage bf23.deletion mutants of bacteriophage bf23 were isolated and the positions of the deletions were determined. two different deletable regions were detected: one in the same region as previously reported for bacteriophage t5, which is closely related to bf23; and the other within both terminal repetitions. the former deletable region lay between positions 0.31 and 0.36, which represented the fractional lengths of the bf23 ( + ) dna as measured from its left end. the latter deletion was evenly divided ...1979430593
is abortive infection by bacteriophage bf23 of escherichia coli harboring colib plasmids due to cell killing by internally liberated colicin ib?infection of escherichia coli harboring colib+ plasmids with bacteriophage bf23+ is abortive and resulted in changes of membrane permeability as measured by efflux of nucleotides and k+. a single pre-early gene product of bf23+ was necessary and sufficient to elicit the abortive response. appropriate mutations in this pre-early gene allowed a productive infection in colib+ cells. appropriate mutations in the colib plasmid also allowed a productive infection with bf23+. a comparison of changes oc ...1979387978
genetic analysis of components involved in vitamin b12 uptake in escherichia coli.the products of three genes are involved in cyanocobalamin (b(12)) uptake in escherichia coli. btub (formerly bfe), located at min 88 on the escherichia coli linkage map, codes for a protein component of the outer membrane which serves as receptor for b(12), the e colicins, and bacteriophage bf23. four phenotypic classes of mutants varying in response to these agents were found to carry mutations that, based on complementation and reversion analyses, reside in the single btub cistron. in one mut ...1977336607
genetics of colicin e susceptibility in citrobacter freundii.the insensitivity of citrobacter freundii to the e colicins is based on tolerance to colicin e1 and resistance to colicins e2 and e3. spontaneous colicin a resistant mutants of c. freundii also lost their colicin e1 receptor function. sensitivity to colicin e1 can be induced by f'gal+tol+ plasmids, the tol a+ gene product of which is responsible for this effect. receptor function for colicins e2 and e3 is induced by the e. coli f'14 bfe+ plasmid, which is also able to enhance notably the recepto ...1977326179
bacterial phage receptors, versatile tools for display of polypeptides on the cell surface.four outer membrane proteins of escherichia coli were examined for their capabilities and limitations in displaying heterologous peptide inserts on the bacterial cell surface. the t7 tag or multiple copies of the myc epitope were inserted into loops 4 and 5 of the ferrichrome and phage t5 receptor fhua. fluorescence-activated cell sorting analysis showed that peptides of up to 250 amino acids were efficiently displayed on the surface of e. coli as inserts within fhua. strains expressing fhua fus ...200111698382
multiple extracellular loops contribute to substrate binding and transport by the escherichia coli cobalamin transporter btub.the escherichia coli outer membrane tonb-dependent transporters for iron complexes and cobalamins recognize their multiple and diverse substrates with high specificity and affinity. the x-ray crystallographic structures of several transporters show that the substrate-binding surfaces are comprised of residues from the internal globular domain and multiple extracellular loops. the extracellular loops on the n-terminal half of the transmembrane beta-barrel of the cobalamin transporter btub partici ...200515716445
the dna region of phage bf23 encoding receptor binding protein and receptor blocking lipoprotein lacks homology to the corresponding region of closely related phage t5.analysis of the dna region upstream of the bf23 hrs gene revealed a genetic organisation similar to that of closely related phage t5. a gene encoding a lipoprotein (llp(bf23)) is located directly upstream of the gene encoding the receptor binding protein (hrs) but is transcribed in opposite direction. the gene is followed by four open reading frames transcribed in the same direction. the llp (bf23) gene product does not show similarity to the corresponding t5 llp(t5) protein, however, like llp(t ...200616598825
pre-early polypeptides of bacteriophages t5 and bf23.nine pre-early polypeptides have been detected after infection with bacteriophage t5 and 10 pre-early polypeptides have been detected after infection with bacteriophage bf23. only about one-half of the coding capacity of the redundant ends of the phage dna, which code for pre-early proteins, is needed for these 9 to 10 pre-early polypeptides. the direction of transcription of pre-early genes a1 and a2 has been established from the size of n-terminal polypeptide fragments induced by amber mutants ...1977325230
functional stability of the bfe and tonb gene products in escherichia coli.the expression of several functional properties of the products of the bfe and tonb genes in escherichia coli was measured after the specific termination of the synthesis of the products of these genes. this was accomplished by the use of a temperature-sensitive amber suppressor mutation, which allowed control, by manipulation of the growth temperature, of the level of product formed from suppressible mutant alleles of the bfe or tonb gene. the bfe product is an outer membrane receptor protein f ...1977233719
physical map of bacteriophage bf23 dna: terminal redundancy and localization of single-chain interruptions.the dna of bacteriophage bf23 possesses two structural features, localized single-chain interruptions and a large terminal repetition, previously described for t5, a closely related virus. as is the case for t5, single-chain interruptions occur with variable frequencies at a small number of fixed sites within one strand of the double-stranded bf23 genome. the sites where interruptions occur with the highest frequencies were napped by an electrophoretic analysis of the single-stranded fragments p ...1979158099
biosynthesis of the outer membrane receptor for vitamin b12, e colicins, and bacteriophage bf23 by escherichia coli: kinetics of phenotypic expression after the introduction of bfe+ and bfe alleles.the bfe locus codes for the cell surface receptor for vitamin b12, the e colicins, and bacteriophage bf23 in the escherichia coli outer membrane. when the bfe+ allele, which is closely linked to the argh locus, was introduced into an argh bfe recipient by conjugation, arg+ recombinant cells rapidly and simultaneously acquired sensitivity to colicin e3 and phage bf23. in the reciprocal experiment introducing bfe into an argh bfe+ recipient, it was found that colicin e3-resistant, arg+ cells began ...1977137230
relationships among genes and gene products of bacteriophage bf23.twenty-five gene products of bacteriophage bf23 were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their functions were studied in relation to type i and ii genes classified by means of genetic complementation tests. all the type i mutants were defective in the synthesis of a tail protein, l3. in addition, 4 type i gene products, l5 (gp21), l7 (gp20), l8 (gp29), and l9 (gp25), were identified as constituents of tails (gp21 denotes that a protein is a product of gen ...19883184273
novel segregation patterns of infecting-mutant genotypes in plate complementation tests among amber mutants of bacteriophage bf23.amber mutants of bacteriophage bf23 were classified into two functional groups, types i and ii, by the yields of the infecting-mutant genotypes in plate complementation tests. type i mutants produced their genotypes at levels more than 20% of the total progeny phages, and type ii mutants did so at levels of less than 5%. comparison of the results of plate complementation tests with those of extract complementation tests revealed that all the type i mutants were defective in the tail formation, w ...19883184272
nucleotide sequence of a dna fragment that contains the abi gene of the colib plasmid.a 1989-bp psti dna fragment from the colib plasmid, which contains the abi gene that is necessary for the abortive response to infections by bacteriophage bf23 or t5, was sequenced. a candidate open reading frame for the abi gene has been suggested on the basis of a shine-dalgarno sequence appropriately placed ahead of its atg initiation codon, a promoter upstream from the shine-dalgarno sequence, and a location compatible with deletion mapping. the polypeptide that would be coded by this open r ...19883072577
regulation of the temporal synthesis of proteins in bacteriophage bf23-infected cells.regulation of temporal synthesis of pre-early, early, and late proteins in bacteriophage bf23-infected cells has been studied by using five amber mutants defective in genes 1, 2, 10, 14, and 19. the synthesis of pre-early proteins is negatively regulated by the actions of gene 1, a pre-early gene. the switch from pre-early to early protein synthesis is mainly regulated by the second-step dna transfer reaction, which is controlled by at least genes 1 and 2. early proteins can be kinetically and g ...19883054152
altered binding and transport of vitamin b12 resulting from insertion mutations in the escherichia coli btub gene.the btub protein of escherichia coli is a multifunctional outer membrane receptor required for the binding and uptake of vitamin b12, bacteriophage bf23, and the e colicins. the btub gene was mutagenized by the insertion of 6-base pair linkers into each of ten hpaii sites distributed throughout the coding region. receptor function was measured with the mutated genes present in single or multiple copies. all of the mutant proteins were found in the outer membrane in similar amounts, although two ...19882844761
point mutations in a conserved region (tonb box) of escherichia coli outer membrane protein btub affect vitamin b12 transport.uptake of cobalamins and iron chelates in escherichia coli k-12 is dependent on specific outer membrane transport proteins and the energy-coupling function provided by the tonb protein. the btub product is the outer membrane receptor for cobalamins, bacteriophage bf23, and the e colicins. a short sequence near the amino terminus of mature btub, previously called the tonb box, is conserved in all tonb-dependent receptors and colicins and is the site of the btub451 mutation (leu-8----pro), which p ...19892687240
abortive phage-infection and uv-protection markers on col i plasmids from epidemic strains of salmonella.cultures of escherichia coli carrying coli plasmids received in conjugation from strains of salmonella typhimurium and s. agona were examined for abortive infection (abi) of phage bf23 and for enhanced resistance to the lethal action of uv-irradiation (uvr). the abi character of stored cultures of e. coli was also compared with the reaction of the same stock culture tested 5 years before. seven of the eight potential types differentiated by three characters were represented among 160 coli plasmi ...19883279216
irreversible binding to the receptor of bacteriophages t5 and bf23 does not occur with the tip of the tail.treatment of purified tails of bacteriophage t5 with 0.05% sodium dodecyl sulfate specifically removed pb2, a protein of 108,000 molecular weight (108k), from the tail. although these tails were devoid of the single straight tail fiber, they still inhibited adsorption of t5 to escherichia coli cells. reconstitution of these tails with pb2 increased the efficiency of inhibition of t5 adsorption. treatment of tails with 0.1% sodium dodecyl sulfate removed, in addition to pb2, a protein of 67k from ...19853886629
a mutant of escherichia coli k12 unable to support the multiplication of bacteriophage bf23. 19734579884
early abortive lysis by phage bf23 in escherichia coli k-12 carrying the colicin ib factor.growth of phage bf23 was restricted in escherichia coli k-12 strains carrying a colicin i factor (colib); most infected cells lysed early without producing progeny phages. either addition of chloramphenicol before phage infection or ultraviolet irradiation of phage prevented early abortive lysis, an indication that certain phage functions are required for this phenomenon. very little or no phage-induced lysozyme was synthesized in the infected coli(+) cells. this result suggests that early abort ...19685701823
arrangement of the single-stranded fragments in e. coli bacteriophage bf23 dna.bacteriophage bf23st(0) dna was denatured with alkali and fractionated by agarose gel electrophoresis. seven single-stranded fragments (designated fragments i--vii) were identified as the major constituents of the phage dna. the presence of several minor fragments which represent minor populations of the phage genome was also observed. the largest fragment (fragment i) represents the intact strand of phage dna, whereas the other fragments form the complementary strand. thus, bf23st(0) dna carrie ...19806245016
physical map of the dispensable region of the genome of e. coli bacteriophage bf23.using 13 deletion mutants of bacteriophage bf23, physical as well as genetic structures of that portion of the genome which is dispensable for phage growth were investigated. the dispensable region covers at least 15% of the genome of wild type bf23, extending from about 0.2 to 0.35 map unit. restriction endonuclease (ecori and hindiii) cleavage sites and the sites of single-strand interruptions in this dispensable region were localized. it was found that the dispensable region contains an inter ...19806245017
physical and genetic analyses of the inc-i alpha plasmid r64.a 126-kilobase (kb) physical and genetic map of the inc-i alpha plasmid r64 was constructed by using the restriction enzymes, bamhi, sali, xhoi, hindiii, and ecori. the replication (rep) and incompatability (inc) functions of this plasmid were located in a 1.75-kb segment of an ecori fragment, e10 (3.3 kb). in addition, the genes determining growth inhibition of phage bf23 (ibf), suppression of dnag ( sog ), resistance to tetracycline (tetr), and resistance to streptomycin ( strr ) were located ...19846327656
outer membrane-dependent transport systems in escherichia coli: effect of repression or cessation of colicin receptor synthesis on colicin receptor activities.proteins in the outer membrane of gram-negative bacteria serve as general porins or as receptors for specific nutrient transport systems. many of these proteins are also used as receptors initiating the processes of colicin or phage binding and uptake. the functional activities of several outer membrane proteins in escherichia coli k-12 were followed after cessation or repression of their synthesis. cessation of receptor synthesis was accomplished with a thermolabile suppressor activity acting o ...19806447139
escherichia coli k317, formerly used to define colicin group e2, produces colicin e7, is immune to colicin e2, and carries a bacteriophage-restricting conjugative plasmid.escherichia coli strain cl137, a k-12 derivative made e colicinogenic by contact with fredericq's strain k317, was unaffected by colicin e2-p9, but k-12 carrying cole2-p9 was sensitive to the e colicin made by strains cl137 and k317. this colicin we named e7-k317 because by the test of colicinogenic immunity it differed from colicins e1-k30, e2-p9, and e3-ca38 and from recently recognized colicins termed e4horak, e5, and e6. strain k317 as conjugational donor transmitted e7 colicinogeny; about h ...19807000748
analysis of btub receptor function by use of nonsense suppression.informational suppression of btub nonsense mutants allows the study of the effect of known, single amino acid substitutions on receptor function. we found that ligand uptake is largely unaffected by such amino acid changes. the few instances in which certain substitutions destroyed sensitivity to the two lethal agents (phage bf23, colicin e3) without affecting vitamin b12 uptake suggest a common region on the btub receptor involved in the binding of these proteinaceous agents.19827050093
sequences of the escherichia coli btub protein essential for its insertion and function in the outer membrane.the escherichia coli btub gene encodes the outer membrane transporter for vitamin b12, the e colicins, colicin a, and bacteriophage bf23. several series of mutant forms of btub resulting from the insertion of dipeptide sequences and from overlapping in-frame deletions and duplications were constructed. strains expressing the variant genes in single and multiple copy numbers were analyzed for btub function, for the level of btub polypeptide in the outer membrane, and for changes in the outer memb ...19957592472
structure-function analysis of the vitamin b12 receptor of escherichia coli by means of informational suppression.we describe a genetic analysis of the vitamin b12 receptor of escherichia coli. through the use of informational suppression, we have been able to generate a family of receptor variants, each identical save for a single, known substitution (ser, gln, lys, tyr, leu, cys, phe) at a known site. we have studied 22 different mutants, 14 in detail, distributed throughout the length of the btub gene. most amino acid substitutions have a pleiotropic effect with respect to all ligands tested, the two col ...19957746157
cloning, sequencing, and expression of bacteriophage bf23 late genes 24 and 25 encoding tail proteins.two bacteriophage bf23 late genes, genes 24 and 25, were isolated on a 7.4-kb psti fragment from the phage dna, and their nucleotide sequences were determined. gene 24 encodes a minor tail protein with the expected m(r) of 34,309, and gene 25 located 4 bp upstream of gene 24 encodes a major tail protein with the expected m(r) of 50,329. when total cellular rna isolated from either phage-infected cells or cells bearing the cloned genes was analyzed by the primer extension method using the primers ...19947961500
identification of the receptor-binding regions of pb5 proteins of bacteriophages t5 and bf23.the receptor-binding protein pb5(t5) of bacteriophage t5, when expressed from the oad gene cloned in pvk88 under the control of the phage t7 promoter/polymerase system, has been shown to bind to its fhua receptor on the surface of e. coli, where it blocks fhua for subsequent adsorption of t5 (mondigler et al., fems microbiol. lett., 130, 293-300, 1995). in the present study the blocking assay has been applied to analyze the effects of several mutations within oad on the fhua-binding properties o ...19968623528
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