共查询到10条相似文献,搜索用时 359 毫秒
1.
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
2.
Molecular characterization of a stable Flac plasmid 总被引:2,自引:0,他引:2
F L Macrina E Balbinder A Bassel 《Biochemical and biophysical research communications》1973,54(2):737-743
FS is a thermostable extrachromosomal element isolated in which is altered in its replication as compared to its precursor Fts114. Sedimentation of both these plasmids in alkaline sucrose gradients has indicated a difference in their sizes. Contour length measurements of open circular plasmid DNA molecules photographed in the electron microscope have revealed the estimated molecular weight of Fts114 to be 81 × 106 daltons while that of FS is 109 × 106 daltons. FS may carry a segment of chromosomal or cryptic plasmid DNA. 相似文献
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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
5.
Pamela Stanley Grace Vivona Paul H. Atkinson 《Archives of biochemistry and biophysics》1984,230(1):363-374
Carbohydrate moieties derived from the G glycoprotein of Vesicular Stomatitis Virus (VSV) grown in parental Chinese hamster ovary (CHO) cells and the glycosylation mutant Lec4 have been analyzed by high-field 1H NMR spectroscopy. The major glycopeptides of and were purified by their ability to bind to concanavalin A-Sepharose. The carbohydrates in this fraction are of the biantennary, complex type with heterogeneity in the presence of α(2,3)-linked sialic acid and α(1,6)-linked fucose residues. A minor glycopeptide fraction, which does not bind to concanavalin A-Sepharose but which binds to pea lectin-agarose, was also investigated by 1H NMR spectroscopy. These carbohydrates are complex moieties which appear to contain N-acetylglucosamine in β(1,6) linkage. Their spectral properties are most similar to those of a triantennary complex oligosaccharide containing a 2,6-disubstituted mannose α(1,6) residue. Carbohydrates of this type are not found among the glycopeptides of VSV grown in the Lec4 CHO glycosylation mutant. 相似文献
6.
Models for decay of Escherichia coli lac messenger RNA and evidence for inactivating cleavages between its messages. 总被引:7,自引:0,他引:7
The size distributions of decaying polycistronic Escherichia coli lac messenger RNA have been followed on polyacrylamide gels. At the same time, equations have been derived that generate the theoretical size distributions of decaying macromolecules for different mechanisms of degradation. Using observed values of lac mRNA metabolism, it was possible to reproduce the in vivo patterns with a model in which cleavage occurs at the start of each of the three messages2 and is followed by a net 5′ to 3′ wave of mass loss. Other models of degradation could not generate the observed in vivo patterns. These alternative mechanisms include: (1) the same number of primary cleavage sites (three) but at different positions on the full-length molecule; (2) an exclusive 5′ to 3′ directional degradation from the start of the lac mRNA (no cleavages); or (3) the presence of many internal targets. Further support for primary cleavage at the start of messages came from the observed accumulation of the intact z mRNA released by cleavage at the boundary and from the predictable effects of specific deletions on the resultant size distributions.The significance of these cleavages has been assessed; they could be necessary “processing” events or, conversely, inactivate the message for translation. Full-length molecules as well as cleavage fragments have been fractionated by successive sucrose gradient centrifugation and tested for their capacity to form translation initiation complexes in vitro. Full-length lac RNA could form such complexes at one or more of its three ribosome-loading sites, whereas the y or a message fragments were inactive. These results suggest that a cleavage at or near the start of a message inactivates it. 相似文献
7.
Alexandre Ghazi Hélène Therisod Emanuel Shechter 《Archives of biochemistry and biophysics》1980,202(1):126-136
Cytoplasmic membrane vesicles isolated from Escherichia coli take up dansyl-galactoside, a fluorescent competitive inhibitor of lactose transport, to much lower levels than lactose. An initial interpretation, based on the study of the fluorescent changes accompanying the energy-dependent uptake, was that it represented a one-to-one specific binding to the lac carrier protein which was not followed by transport. Recently, on the basis of a new estimation of the number of lac carrier in the membrane, it has been advanced that the uptake of dansyl-galactoside represents a nonspecific binding on the inner surface of the membrane following transport. We discriminate between the two interpretations by comparing the effects of lactose and dansyl-galactoside uptake on the electrochemical gradient of protons (), generated by the oxidation of substrates, and on the uptake of proline. Indeed, it is known that the rate of lactose transport is such that it leads, as a consequence of the lactose/H+ symport, to an observable decrease of , and secondary to this decrease to an inhibition of the uptake of proline transported at much lower rate. We show that the rates of uptake of lactose and dansyl-galactoside by the membrane vesicles are similar; yet the uptake of dansyl-galactoside does not lead to the uncoupling effects which are associated with the uptake of lactose. We discuss the possible reasons for the absence of this uncoupling effect, and we conclude that our data are incompatible with the notion that the energy-dependent uptake of dansyl-galactoside is associated with an active transport involving a dansyl-galactoside/H+ symport. On the contrary, the data substantiate the initial interpretation that the energy-dependent uptake of dansyl-galactoside reflects the binding to the lac carrier not followed by transport. 相似文献
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Membrane mutation related to the production of extracellular -amylase and protease in bacillus subtilis 总被引:13,自引:0,他引:13
Mutants which had a genetic character to increase the production of both α-amylase and protease simultaneously, were isolated from a transformable strain of Marburg by NTG treatment. This mutation seems to have occurred at a single gene of the bacterial chromosome and was not linked to 116 which was closely linked to the α-amylase gene. When this mutation and an α-amylase regulator gene (h) coexisted in one strain, their synergistic effect on extracellular α-amylase production ws observed. The introduction of this mutation resulted in a loss of competence for the transformation. The SDS disc gel electrophoretic profiles of the membrane proteins from the original strain, the mutants and transformants with this mutation showed a remarkable difference in one component. 相似文献
10.
In vitro translation of mRNA from rat pheochromocytoma tumors, characterization of tyrosine hydroxylase 总被引:8,自引:0,他引:8
Studies are presented which demonstrate that rat pheochromocytoma tumors are a convenient material for the preparation of tyrosine hydroxylase mRNA. Total pheochromocytoma poly(A)+mRNA has been extracted from tumors, then translated in a reticulocyte lysate cell-free system. Neo-synthesized tyrosine hydroxylase has been identified by direct immunoprecipitation followed by sodium dodecyl sulfate acrylamide gel electrophoresis. The proportion of this specific mRNA has been calculated; it represents 0.15 per cent of the total poly(A)+mRNA. The molecular weight of the synthesized tyrosine hydroxylase is 62,000. 相似文献