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E Amann

Publications and source records attributed to E Amann.

At least 55 records · Page 3Linked to original sources
PubMed1983

Vectors bearing a hybrid trp-lac promoter useful for regulated expression of cloned genes in Escherichia coli.

A strong promoter has been cloned on a series of plasmid vectors that facilitate the expression of cloned genes. This promoter, named tac [first described by DeBoer et al. (in Rodriguez, R.L. and Chamberlin, M.J. (Eds.),Promoters, Structure and Function. Praeger, New York, 1982, pp. pp. 462-481)] contains the -10 region of the lacUV5 promoter and the -35 region of the trp promoter. Our vectors contain various cloning sites followed by transcription termination signals. In addition, we describe plasmids that facilitate the conversion of the lac promoter to the stronger tac promoter. Thus, preexisting gene fusions using the lac or the lacUV5 promoter can be readily converted to tac promoter gene fusions without changing the ribosome-binding site (RBS). The tac promoter is repressed in lacIQ strains and can be induced by isopropylthio-beta-D-galactoside (IPTG). Studies of expression of the cI repressor of bacteriophage lambda show that the tac promoter is at least five times more efficient than the lacUV5 promoter. Under optimal conditions lambda repressor constitutes up to 30% of the total cellular protein.

Bacterial Proteins↗
PubMed1983

Purification of biologically active simian virus 40 small tumor antigen.

The simian virus 40 small tumor antigen (t antigen) gene has been cloned downstream from a hybrid Escherichia coli trp-lac promoter and a suitable ribosome binding site. A bacterial clone (865i) transformed by such a plasmid (pTR865) expresses this gene and, under optimal conditions, can produce greater than or equal to 5% of its total protein as t antigen. Soluble extracts of such a clone were relatively depleted in t antigen, which was found in the initial pellet fraction. The protein was recovered from this fraction in a significantly purified form by extraction with urea-containing buffer. After gel filtration of such t antigen-enriched solutions, highly purified protein was obtained. When either this fraction (freed of urea) or NaDodSO4 gel-purified 865i t antigen (rendered free of detergent) was injected into untransformed rat cells, dissolution of intracellular actin cable networks was observed.

Animals↗
PubMed1980

Unusual behaviour of SPO1 DNA with respect to restriction and modification enzymes recognizing the sequence 5'-G-G-C-C.

SPO1 DNA contains only 5 cleavage sites for restriction enzymes which recognize and cleave the sequence 5'-G-G-C-C (HaeIII or BsuR). Fragments of SPO1 DNA cloned in E. coli to substitute 5'-hydroxymethyluracil (HMU) by thymine (T) remain resistant to HaeIII indicating that this unexpectedly small number of cleavages by HaeIII is not correlated with the presence of HMU in the normal phage DNA. It was previously shown that SPO1 is neither subject to B. subtilis R restriction (Trautner et al., 1974) nor modification in vivo (Günthert et al., 1975). We now show that SPO1 DNA can however be restricted and modified in vitro.

Bacteriophage lambda↗
PubMed1979

Bacteriophage SPP1 polypeptides synthesized in infected minicells and in vitro.

Minicells produced by B. subtilis CU403divIVB1 and infected by SPP1 synthesize at least 46 polypeptides which can be separated by polyacrylamide gel electrophoresis. These polypeptides represent the expression of 86% of the SPP1 genome's coding capacity. Infection of minicells by sus mutants and deletion mutants of SPP1 has permitted a correlation of genetic location with gene product and has shown that SPP1 normally synthesizes at least 8 non-essential polypeptides. Restriction fragments of SPP1 produced by EcoRI digestion of SPP1 DNA have been purified and used as template DNA in a coupled transcription/translation system derived from E. coli to determine the polypeptides encoded by the individual fragments. SPP1 expression in minicells differs from SPP1 expression in nucleated cells (Esche, 1975) in that late syntheses are not dependent on phage DNA replication in infected minicells.

Bacillus subtilis↗
PubMed1978

DNA synthesis in toluene-treated bacteriophage-infected minicells or Bacillus subtilis.

Bateriophage (phi29, SPP1, or SPO1)-infected, toluene-treated minicells of Bacillus subtilis are capable of limited amounts of non-replicative DNA synthesis as measured by incorporation of [3H]dTTP into a trichloroacetic acid-precipitable form. The [3H]dTTP is covalently incorporated into small DNA fragments which result from the degradation of a small percentage of the infecting phage genomes (molecular weights in the range of 2 . 10(5)). Short exposure of the DNA molecules containing the incorporated [3H]dTMP to Escherichia coli exonuclease III results in over 90% of the E13H]dTMP being converted to a trichloroacetic acid-soluble form. The synthesis is totally dependent on host-cell enzymes and is not inhibited by the addition of chloramphenicol, rifampicin, nalidixic acid and mitomycin C and only slightly (approx. 20%) inhibited by the addition of 6-(p-hydroxyphenylazo)-uracil.

Bacillus subtilis↗
PubMed1978

[The value of scintigraphy for the early detection of osteomyelitis (author's transl)].

For therapy and development of acute haematogenic osteomyelitis early detection of this disease is decisive. In our study 74 children were investigated scintigraphically with Tc-pyrophosphat because of suspicion of an inflammatory bone process. In all 23 cases of osteomyelitis scintigraphy showed an indication in form of increased activity in the respective bones; so the sensivity of this investigation, found in our study, was 1.0. In 10 of 51 cases without osteomyelitis scintigraphy, however, also showed increased activity. Because of this limited specifity of scanning further investigations are needed in the diagnosis of osteomyelitis. The main advantage of scintigraphy as compared with roentgen observation is the high sensitivity in the first days of illness. In addition scanning may supply valuable informations about the inflammatory process as long as it is active.

Child↗