Biomedical subjects

I Bölin

Publications and source records attributed to I Bölin.

25 records · Page 2Linked to original sources

PubMed1985

Expression of the temperature-inducible outer membrane proteins of yersiniae.

The expression of the temperature-inducible plasmid-coded outer membrane proteins (YOPs) of Yersinia pseudotuberculosis was studied. These proteins were not recovered in the outer membrane fraction when the strain was grown in minimal medium at 37 degrees C, but they were expressed under these conditions. A strict correlation was found between Ca2+ dependency in the virulent strain, YPIII(pIB1), and ability to express YOPs. Ca2+-independent plasmid mutants or RNA-polymerase mutants harboring the virulence plasmid were unable to express YOPs, in contrast to the wild-type strain. These strains were also found to be avirulent. Sera recovered from patients or animals undergoing infection with either Y. pseudotuberculosis, Y. pestis, or Y. enterocolitica possessed antibodies directed against YOPs, indicating that they were expressed in all three pathogenic Yersinia species during infection. The YOPs of the three different species showed high immunological relatedness.

Animals↗

PubMed1985

Transfer of the virulence plasmid of Yersinia pestis to Yersinia pseudotuberculosis.

Transposon Tn5 insertion derivatives of the virulence plasmid pYV019 of Yersinia pestis were transferred by P1 transduction into a plasmid-free strain of Y. pseudotuberculosis. One of these plasmid derivatives conferred virulence upon the Y. pseudotuberculosis strain. This strain had the ability to express temperature-inducible plasmid-coded outer membrane proteins and was also found to be Ca2+ dependent.

Animals↗

PubMed1984

Molecular cloning of the temperature-inducible outer membrane protein 1 of Yersinia pseudotuberculosis.

When Yersinia pseudotuberculosis is shifted from growth at 26 degrees C to growth at 37 degrees C, the synthesis of a plasmid-associated outer membrane protein, protein 1, is induced (Bölin et al., Infect. Immun. 37:506-512). The structural gene of this protein was found to be located on the virulence plasmid pIB1 of Y. pseudotuberculosis. One cosmid hybrid plasmid pBW8 was studied which carried a region of the virulence plasmid. This hybrid plasmid expressed in Escherichia coli K-12 a novel temperature-inducible outer membrane protein which is immunologically related to and has the same molecular weight as protein 1. Protein 1 was purified to homogeneity, and 14 amino acids of the N-terminal end were determined. From this sequence, the tentative corresponding DNA sequence was deduced, and a set of 11-nucleotide-long DNA probes was chemically synthesized. By using these probes in Southern blotting experiments, the genetic location of the N-terminal end of protein 1 was established. By introducing the transposon Tn5 into the virulence plasmid pIB1, mutants were obtained that did not express protein 1. One class of these mutants was still Ca2+ dependent and virulent, suggesting that protein 1 is not a major virulence determinant. Tn5-derived insertion mutants were also obtained which were Ca2+ independent. Such mutants were found to be avirulent. One Ca2+-independent mutant still expressed protein 1, indicating that the regulatory expression of protein 1 is not linked to Ca2+ dependence.

Amino Acid Sequence↗

PubMed1984

Virulence plasmid-associated autoagglutination in Yersinia spp.

The autoagglutination of Yersinia enterocolitica was dependent on the presence of the virulence plasmid and on the active growth of bacteria in tissue culture media at 37 degrees C. Cultures with a high initial concentration of bacteria failed to autoagglutinate , indicating that synthesis of new virulence plasmid-associated surface factors was essential for autoagglutination. The synthesis of a plasmid-encoded polypeptide (molecular weight, 240,000), designated P1, that could be dissociated under strongly reducing conditions into subunits of 52,500 daltons was found to be correlated with autoagglutination. Further, a strain of Yersinia pseudotuberculosis [ YPIII ( PIB102 )], which has Tn5 inserted within the structural gene of P1 that prevents the synthesis of P1, failed to autoagglutinate , in contrast to the wild-type strain, strongly indicating that P1 is involved in this phenomenon. It was also found by immunoblotting that in addition to the common response to temperature, the P1 proteins of Y. enterocolitica and Y. pseudotuberculosis were immunologically related.

Agglutination↗

PubMed1983

Interaction between Yersinia pseudotuberculosis and the HeLa cell surface.

The adherence of Yersinia pseudotuberculosis to the surface of HeLa cells at 4 degrees C was studied. This temperature allows adhesion of bacteria but prevents engulfment. Adhesion between the bacteria and the cells was not dependent upon the presence of serum, Ca2+ or Mg2+ in the medium. Maximum adhesion was obtained at pH 6.5-7.9 and pretreatment of the cells with formaldehyde or glutaraldehyde inhibited the attachment of the bacteria. The interaction between the bacteria and the cell surface seems to involve cellular processes that are mostly microvilli. An intimate association between the bacteria and the cellular glycocalyx was found. Three virulent bacterial strains adhered more easily to the cell surface than five avirulent strains. Maximum adherence was obtained with bacteria from late logarithmic and early stationary phases of growth. The bacteria gradually lose their adhesive property when cultivated for several generations at 37 degrees C in nutrient broth but not when cultivated at 20 degrees C. Treatment of the bacteria with protease IV from Streptomyces caespitosus markedly reduced the efficiency of attachment.

Adhesiveness↗

PubMed1982

Temperature-inducible outer membrane protein of Yersinia pseudotuberculosis and Yersinia enterocolitica is associated with the virulence plasmid.

A strain of Yersinia pseudotuberculosis which harbors a 63-kilobase plasmid was found to cause a lethal infection in Swiss albino mice. The rate of infection paralleled the ability of the pathogenic organism to attach to a monolayer of HeLa cells. One novel outer membrane protein (protein 1) with a molecular weight of 140,000 was found to be associated with the possession of the 63-kilobase plasmid not at 26 degrees C, and expression was moderately affected by the concentration of calcium in the growth medium. Moreover, it was found that synthesis of protein 1 associated outer membrane protein showing similar properties was also found to be expressed in plasmid-containing strains of Yersinia enterocolitica. The properties of protein 1 indicate that it could be identical to the previously described virulence W antigen.

Adhesiveness↗

PubMed1980

Ingestion of Yersinia pseudotuberculosis into human fibroblasts in vitro.

The ingestion into human fibroblasts of different strains (avirulent and virulent) of Yersinia pseudotuberculosis was investigated. The kinetics of ingestion was studied with the addition of 10(7) bacteria to human lung fibroblast cultures. The number of ingested bacteria after 0.5-3 h was measured with viable count technique. All strains were ingested except for one avirulent strain. The other strains were ingested at roughly the same rate. The bacterial uptake seemed to be mediated by a phagocytic-like procedure and the intracellular bacteria resided in vacuoles. The bacteria survived and also multiplied in the cells (for at least 7 days).

Cell Line↗