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P Klaasen-Boor

Publications and source records attributed to P Klaasen-Boor.

7 recordsLinked to original sources
PubMed1980

Production of K99 antigen by enterotoxigenic Escherichia coli strains of antigen groups o8, o9, o20, and o101 grown at different conditions.

The production of the K99 antigen by enterotoxigenic Escherichia coli strains with various O antigens was investigated by means of slide agglutination tests, enzyme-linked immunosorbent assays, and hydrophobic interaction chromatography. The extent of K99 production appeared to be dependent on the nutrient medium, as well as on the incubation temperature. Minimal salt medium with glucose and semisynthetic Minca medium were the most suitable for K99 production. In complex media the production of K99 antigen was strongly reduced. Optimal amounts of K99 antigen were produced at 37 degrees C. At 30 degrees C, weak production of K99 antigen was detected by hydrophobic interaction chromatography of enzyme-linked immunosorbent assay. Slide agglutination tests were negative with cultures grown below 32 degrees C. The production of K99 antigen appeared to be related to the O antigen carried by the host strain, but it seemed to be independent of the absence or the presence of various K polysaccharide antigens. Under all conditions used, strains with antigen O101 produced about 10 times more K99 antigen than did strains with antigen O8, O9, or O20. Transfer of the K99 plasmid from wild-type strains of different O antigens to E. coliK-12 C600 confirmed that phenotypic expression of the K99 antigen is most probably related to the cell wall composition of the host.

Animals↗
PubMed1980

Biosynthesis of the K99 surface antigen is repressed by alanine.

The amino acid alanine induced a direct and specific repression of the biosynthesis of the K99 surface antigen in Escherichia coli strains harboring the K99 plasmid. In minimal medium with 0.5% glucose, 1 mM L-alanine was sufficient to reduce the K99 production by about 95%. The low production of the K99 antigen by strains growing on commercially available nutrient media seemed to be a result of the inhibitory effect alanine on the K99 biosynthesis.

Alanine↗
PubMed1979

Purification and characterization of cloacin DF13 receptor from Enterobacter cloacae and its interaction with cloacin DF13 in vitro.

Extraction of the crude cell envelope fraction of cloacin DF13-susceptible Enterobacter cloacae strain 02 with Triton X-100 and ethylenediaminetetraacetate solubilized an outer membrane fraction which neutralized the lethal activity of cloacin DF13. A similar fraction could not be isolated from strains known to be lacking functional cloacin DF13 receptors. On this basis the isolated outer membrane fraction was assumed to contain the specific cloacin DF13 receptor. The receptor was purified to homogeneity by acetone precipitation and affinity chromatography, using cloacin DF13 as a ligand. The purified receptor was identified as a protein which consisted of a single polypeptide chain with an apparent molecular weight of 90,000 and a preponderance of acidic amino acids (pI = 5.0). The interaction of equimolar amounts of purified receptor and cloacin DF13 in vitro resulted in a complete, irreversible neutralization of the lethal activity of the bacteriocin. This interaction showed a temperature optimum at 43 degrees C but was only slightly affected by variation of the pH between 5.0 and 8.5 or by increasing the ionic strength of the incubation buffer. The receptor had no neutralizing activity towards other bacteriocins, such as colicin E1 or colicin E3.

Bacterial Proteins↗
PubMed1977

Purification and characterization of a complex between cloacin and its immunity protein isolated from Enterobacter cloacae (Clo DF13). Dissociation and reconstitution of the complex.

Cell of Enterobacter cloacae (Clo DF13) produce a bacteriocin which is characterized by its very effective killing activity against sensitive bacteria. Purification and characterization of the excreted bacteriocin has revealed that this bacteriocin consists of an equimolar complex of two plasmid-specific gene products: the cloacin and its inhibitor the immunity protein. Dissociation of the complex by treatment with sodium dodecylsulfate induces the endonucleolytic activity of the cloacin but strongly reduces the killing activity. The purified complex possesses no activity in vitro. Both cloacin and immunity protein isolated from the complex were functionally identical to cloacin and immunity protein purified from the bacteriocinogenic cells by other methods. Reconstitution of the complex results in a partial restoration of killing activity.

Amino Acids↗
PubMed1975

Mode of action of the cloacin DF13-immunity protein.

1. Cells of Enterobacter cloacae harbouring the bacteriocinogenic factor Clo DF13 produce an immunity protein which inbhbits the in vitro activity of cloacin DF13. The amino acid composition of purified immunity protein was determined. 2. Experiments about the protection of ribosomes against cloacin DF13 in the presence of the immunity protein show that one molecule of immunity protein neutralized the activity of one molecule cloacin. 3. Direct and specific interaction of cloacin DF13 with the immunity protein has been demonstrated by the analysis of mixtures of both proteins on polyacrylamide gels and by changes in the fluorescence response of cloacin DF13-bound 1-anilinonaphthalene-8-sulfonate in the presence of immunity protein.

Amino Acids↗