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1.
An enlarged threshold model of the Regulatory System of Development of λ-Phage (RSDP λ-2) is built. It includes 15 synthetic blocks of proteins and mRNAs and four blocks corresponding to the other ontogenetic processes: two-stage replication, integration and excision of phage genome, formation of oligomers of regulatory proteins, regulation of bacteriallysis. By way of computer simulation of the RSDP λ-2 model the dynamics of concentrations of all main proteins, respective fractions of mRNAs and DNA are described in the lytic and lysogenic regimes of phage ontogenesis. Results obtained are in good agreement with available experimental data. The dependence of a portion (%) of lysogenic responses on the multiplicity of phage infection of bacterial culture, is built. This curve has a maximum point in accordance with the experimental data of P. Kourilsky (1973). 相似文献
2.
carrying a temperature-sensitive mutation and lysogenic for phage P2 was able to grow normally even at 42°C, at which temperature the bacteria are phenotypically . At this temperature, the bacteria were, however, unable to support the growth of λspi? phages. 相似文献
3.
Identification of an Escherichia coli inner membrane polypeptide specified by a lambda-tonB transducing. 总被引:1,自引:0,他引:1
Analysis by polyacrylamide gel electrophoresis of the proteins coded by a λB transducing phage, after infection of UV-irradiated bacteria, revealed the presence of at least 7 new polypeptides. Three of these were identified as proteins of the operon whilst three others were deleted by a spontaneous mutation in the B region carried by the phage. A single polypeptide, molecular weight 40,000 was absent from a phage carrying a proflavine induced mutation in B. We conclude that this protein, which was localised in the inner membrane by sarkosyl fractionation of the envelope, is the product. 相似文献
4.
P. Dhaese A. Lenaerts J. Gielen M. Van Montagu 《Biochemical and biophysical research communications》1980,94(4):1394-1400
As part of a project intending to assess the evolutionary kinship between the RNA coliphages and RNA bacteriophages of other bacterial genera, we have sequenced the coat protein of RNA phage PP7. Like the coat proteins of coliphages MS2 and Qβ and of the broad host range RNA phage PRR1, PP7 coat protein (127 residues) is highly hydrophobic, and contains a cluster of basic residues between positions 40 to 60. Minimal mutation distance values were calculated for comparison of PP7 coat protein with each MS2, Qβ and PRR1 coat proteins. Application of the Moore-Goodman criterion to those values, shows that these four RNA bacteriophage coat proteins very likely descent from a common ancestor. 相似文献
5.
The structural stabilities of the T7 early mRANs were measured and found to vary according to whether chloramphenicol or puromycin were added before or after infection with phage T7. These antibiotics had little effect upon messenger stability when they were added prior to infection. When chloramphenicol (but not puromycin) was added after completion of T7 early mRNA synthesis, the structural stability of the messages was enhanced. Messages which are inefficiently translated due to altered 5′-termini were not stabilized by the late addition of chloramphenicol. We interpret these results to mean that ribosomal protection of the T7 early mRNAs is responsible for the increase in messenger structural stability in the presence of chloramphenicol. 相似文献
6.
Uracil-DNA glycosylase of is involved in repair of deaminated cytosine residues of DNA. Survivals of SPO2 phage after treatment with bisulfite and weak alkali are considerably higher in wild type strains than in mutants, which are deficient in the enzyme activity, whereas survivals of bisulfite/alkali-treated PBS1 phage in the two types of cells are essentially the same. The spontaneous mutation frequency of a mutant is three fold higher than is that of a wild type strain. 相似文献
7.
The replication defective transducing phage λp3 carries a portion of the operon in the 2 region of the lambda phage. This operon segment contains the promoter, the operator, and the β-galactosidase gene, but does not contain the repressor gene. The gene can be expressed from both the inserted promoter and the phage promoter. When strain 594 (?, +) or JC6256 (Δ) is infected by λp3 in the absence of additional cyclic AMP, β-galactosidase synthesis is shown to be expressed from the phage promoter. When 594 (λ+) or JC6256 (λ+) is infected by λp3 in the presence of additional cyclic AMP and IPTG, β-galactosidase synthesis is shown to be expressed from the inserted promoter.The ability to separate the phage promoter from the inserted promoter for β-galactosidase expression will simplify the interpretation whenever λp5 is used. 相似文献
8.
DNA-free minicells of will not allow growth of phage T-7, nor is RNA synthesis stimulated by phage infection. Thus, these miniature cells seem not to contain RNA polymerase activity. However, DNA-dependent RNA polymerase activity can be unmasked in extracts with poly(dA-T) and Mn2+. This activity may represent a cytoplasmic pool of inactive RNA polymerase in normal cells. 相似文献
9.
Peter J. Natale Carrie Ireland John M. Buchanan 《Biochemical and biophysical research communications》1975,66(4):1287-1293
Messenger RNA for two T4 specific enzymes, deoxynucleotide kinase and α glucosyltransferase, have been sized by sedimentation on sucrose density gradients. The sedimentation constants of transferase and kinase mRNAs formed were 21.5S and 14.5S respectively, regardless of the duration of incubation up to 20 min. Although the kinase mRNA isolated from cells infected with T4 phage for 10 min was the same size as found (14.5S), the transferase mRNA was found in a segment approximating the size of the kinase mRNA (14.5S). The experiments indicate that α glucosyltransferase mRNA is formed first as a polycistronic message and is then processed to the smaller unit. 相似文献
10.
Emanuel Goldman Harvey F. Lodish 《Biochemical and biophysical research communications》1975,64(2):663-672
In an cell-free protein synthesis assay, mRNA isolated from cells late after infection by phage T4 out-competes bacteriophage f2 RNA. Addition of a saturating or subsaturating amount of T4 mRNA inhibits translation of f2 RNA, while even an excess of f2 RNA has no effect on translation of T4 mRNA. Peptide mapping of reaction products labeled with formyl-[35S]-methionyl-tRNA was used to quantitate f2 and T4 protein products synthesized in the same reaction. We suggest that messenger RNA competition might be one mechanism by which T4 superinfection of cells infected with phage f2 blocks translation of f2 RNA and possibly host mRNA. 相似文献
11.
Diffusion of tetracycline across the outer membrane of Escherichia coli K-12: involvement of protein Ia. 总被引:4,自引:0,他引:4
The possibility that passage of tetracycline across the outer membrane of K-12 is controlled by one or more of the proteins Ia, Ib and II1 (Henning's nomenclature) was investigated. A mutant lacking protein Ia (obtained by selection for resistance to phage TuIa) was more resistant to tetracycline than wild-type strains or those lacking only proteins Ib or II1. The envelope protein composition of a tetracycline-resistant mutant () was altered in several respects, but the major change involved loss of protein Ia. These data support our previous suggestion [12] that tetracycline diffuses across the outer membrane through hydrophilic regions. Furthermore, they imply that only protein Ia plays a significant role in the passage of this antibiotic across the outer membrane. 相似文献
12.
Giant T4 bacteriophage were found by Doermann et al. (1973a) with point mutants in gene 23 and by Cummings et al. (1973) after l-canavanine induction followed by an arginine chase. We now find T4 giant phage with 14 out of 15 tested temperature-sensitive mutants in gene 24 grown at intermediate temperatures between 33 °C and 37 °C.For one of these mutants, T4,24(tsB86), we found that (a) the optimum temperature for giant phage production is 34.8 °C, (b) the head-length distribution peaks sharply between 10 and 12 normal T4 phage head lengths, (c) about 75% of our giant phage have two tails, (d) the buoyant density in CsCl is greater than that of normal phage, (e) they are infectious and show an increased u.v. resistance, (f) their sodium dodecyl sulphate gel electrophoresis pattern is qualitatively similar to that of normal T4 phage, although the relative intensities of some of the bands are different, showing for example, a decreased 2 ratio, (g) optical diffraction and filtering of the flattened cylindrical part of the giant heads show a p6 surface net with a lattice constant of approximately 130 Å, a unique ratio of and a capsomer morphology of the type 1 + 6 + 6.Mixed infections with T4 wild type and T4.24(amN65) also yield giant phage. These are produced in highest amounts with a multiplicity of infection ratio of 5:5; no giants are observed at ratios of 1:9 or 9:1, suggesting that their formation may be caused by a dosage effect of P24. 相似文献
13.
The synthesis of β-galactosidase (EC 3.2.1.23: β-D-galactoside galactohydrolase) in is repressed as a result of infection with single-stranded DNA phage ØX174. An mutant in ØX174 cistron A, which codes for two proteins, does not inhibit the enzyme synthesis while mutants in all other genes do cause repression. A mutant near the amino-terminal end of cistron A, which produces the small 35,000 molecular weight cistron A polypeptide, also inhibits the synthesis of β-galactosidase. Inhibition is also observed in an mutant which does not support the replication of replicative-form DNA. Exogenous nucleotide bases and cyclic 3′,5′-adenosine monophosphate (cyclic AMP) do not have any effect on the degree of repression. 相似文献
14.
Thiolutin resistant mutants of can not support the development of phage P22 at high temperature (40°C). Although normal amounts of phage DNA and lysozyme are synthesised, very few infectious particles are formed at higher temperature. The results indicate the involvement of host function in phage development. 相似文献
15.
G W Pettigrew I Aviram A Schejter 《Biochemical and biophysical research communications》1976,68(3):807-813
Phage ?15 adsorbed at a low temperature (or by short-time incubation) to the outer surface of gathers on further incubation at a high temperature to a certain region where the inner and outer membranes may join. This was demonstrated by separating the inner and outer membranes of the cells in sucrose gradient after addition of 35S-labeled ?15 to the cells. Radioactivity adsorbed at 4° was first recovered mainly with the dense outer membrane but disappeared by further incubation at 35° within 5 min. Instead, the radioactivity was recovered with the membrane fraction which had intermediate density. Such phage translocation was not observed when phage ?15 was added to a to which the phage can adsorb but fail to infect. A host range mutant phage which can infect the mutant migrated to the intermediate dense region. 相似文献
16.
H Kung M Tainsky H Weissbach 《Biochemical and biophysical research communications》1978,81(3):1000-1010
The regulation of the synthesis of the N-terminal portion of the β-galactosidase molecule (α-peptide) has been investigated using DNA fragments of the lactose operon as template. DNA fragments of about 789 base pairs were isolated after endonuclease (Hin II) digestion of either λplac5, λh80dlacps or λh80dlacUV5 phage DNA or DNA from the recombinant plasmid PMC3. The regulation of the expression of these fragments is similar to that observed for the synthesis of β-galactosidase using total phage or plasmid DNA as template, indicating that the regulatory regions on the fragments are intact and functional. Thus, the synthesis of the α-peptide required an inducer due to the presence of repressor in the S-30 extract used. In addition a dependency on adenosine 3′,5′-cyclic monophosphate (cAMP)1 for α-peptide synthesis was obtained with the fragments isolated from λplac5 and λh80dlacps DNAs, whereas little effect of cAMP was seen with the fragment isolated from λh80dlacUV5 phage DNA or PMC3 plasmid DNA containing a UV5 promotor region. However, a significant difference in the effect of guanosine-3′-diphosphate-5′-diphosphate (ppGpp) was observed. With the total phage DNA as template, ppGpp resulted in a 2–4 fold stimulation whereas with the fragment, or PMC3 plasmid DNA, directed synthesis of the α-peptide no significant stimulation by ppGpp was seen. 相似文献
17.
In order to help bridge the conceptual gap between experimental data on chains of phospholipid molecules and their microscopic organization, a theoretical model has been proposed in a preceding paper. The intentions associated with the new theory were to describe a model able to reproduce accurately the experimental data. This capability is essential to monitor some of the mechanisms behind the physical data. The results presented here show first that, provided a suitable fitting of the phenomenological parameters entailed in the model, the theory indeed gives good agreement with experimental data (2H-NMR, neutron scattering, calorimetry) obtained for a bilayer. This property of the model is then specifically used to describe the nature of the perturbing effects of local anaesthetics and cholesterol on the organization of the acyl chains and to correlate these effects with the experimental data. Finally the theoretical model is used to supplement experimental data by describing the acyl chain organization in terms of the most probable spectrum of chain conformations. Predictions are made about the one-, two- and three-dimensional mean spatial characteristics of the acyl chains. 相似文献
18.
S Lemaire L Chouinard D Denis M Panico H R Morris 《Biochemical and biophysical research communications》1982,108(1):51-58
Deliberate miscompartmentalization of liver outer mitochondrial membrane (OMM) proteins and liver mitochondrial proteins has been achieved by polyethylene-glycol mediated OMM vesicle-hepatocyte or mitochondrial-hepatocyte fusion. Reductively methylated OMM and mitochondrial proteins (3H) are destroyed at rates remarkably similar to those for OMM (, 60–70 h) or mitochondrial proteins (, 84–104 h) in liver when studied over 4–5 days in hepatocyte monolayers cultured in conditions giving stabilized endogenous protein catabolic rates mimicking endogenous rates. Destruction of transplanted OMM proteins is partially sensitive to chloroquine, supporting some lysosomally mediated autophagic destruction of long-lived transplanted OMM proteins in hepatocyte monolayers. 相似文献
19.
Uri Nudel Jane Salmon Eitan Fibach Masaaki Terada Richard Rifkind Paul A. Marks Arthur Bank 《Cell》1977,12(2):463-469
The accumulation of α- and β-globin mRNA sequences in murine erythroleukemia cells (MELC) treated with various inducers has been studied using specific α- and β-globin complementary DNAs (cDNAs). In cells cultured with dimethylsulfoxide (Me2SO), hexamethylene bisacetamide (HMBA) or butyric acid, accumulation of α-globin mRNA is detectable after 16, 12 and 8 hr of culture, respectively. An increase in β-globin mRNA sequences is not detected until 20–24 hr after culture. In cells exposed to hemin, both α- and β-globin mRNAs are detectable by 6 hr of culture, and a constant ratio of is maintained during induction. In maximally induced cells, the mRNA ratios are approximately 1 in cells induced by Me2SO and HMBA, and 0.66 and 0.3–0.50 in cells induced by butyric acid and hemin, respectively. Thus different inducers of erythroid differentiation in MELC lead to different times of onset of the expression of α- and β-like genes. In addition, the relative accumulation of α- and β-globin mRNAs in induced cells differs with various types of inducers. 相似文献
20.
B J Knoll 《Journal of molecular biology》1979,132(3):551-555
Efficient lysogenization of Escherichia coli K12 by bacteriophage λ requires the high level of synthesis of the phage repressor shortly after infection. This high level of synthesis of repressor requires the action of the λ eII and cIII proteins. Certain mutants of λ (λcIIIs) appear to have excess activity and can lysogenize more efficiently than λ+. The basis for the enhanced lysogenization is that, while two or more infecting phage are necessary for λ+ to lysogenize, a single infecting λcIIIs particle is sufficient for lysogenization. Also, repressor levels in cells infected with λcIIIs are higher than in those infected with λ+. I report here that repressor overproduction by λcIIIs (1) is due to a much higher rate of repressor synthesis than that of λ+; (2) is most marked at low multiplicities of infection, possibly because λcIIIs produces repressor much more efficiently than λ+ as a singly infecting phage. 相似文献