Biomedical subjects

J Luirink

Publications and source records attributed to J Luirink.

59 records · Page 4Linked to original sources

PubMed1987

Modification, processing, and subcellular localization in Escherichia coli of the pCloDF13-encoded bacteriocin release protein fused to the mature portion of beta-lactamase.

A fusion between the pCloDF13-derived bacteriocin release protein and beta-lactamase was constructed to investigate the subcellular localization and posttranslational modification of the bacteriocin release protein in Escherichia coli. The signal sequence and 25 of the 28 amino acid residues of the mature bacteriocin release protein were fused to the mature portion of beta-lactamase. The hybrid protein (Mr, 31,588) was expressed in minicells and whole cells and possessed full beta-lactamase activity. Immunoblotting of subcellular fractions revealed that the hybrid protein is present in both the cytoplasmic and outer membranes of E. coli. Radioactive labeling experiments in the presence or absence of globomycin showed that the hybrid protein is modified with a diglyceride and fatty acids and is processed by signal peptidase II, as is the murein lipoprotein. The results indicated that the pCloDF13-encoded bacteriocin release protein is a lipoprotein which is associated with both membranes of E. coli cells.

Bacterial Proteins↗

PubMed1986

Effects of divalent cations and of phospholipase A activity on excretion of cloacin DF13 and lysis of host cells.

Induction of cloacin DF13 synthesis in Escherichia coli harbouring plasmid CloDF13 results in the release of cloacin DF13, inhibition of growth and ultimately in lysis of the host cells. Expression of the pCloDF13-encoded protein H is essential for both the release of cloacin DF13 and the lysis of the cells. The divalent cations Mg2+ and Ca2+ interfered with the mitomycin C-induced protein H-dependent lysis, but hardly affected the release of cloacin DF13. Essentially all of the bacteriocin was released from the cells before a detectable degradation of the peptidoglycan occurred, independent of the presence of mitomycin C. Experiments with phospholipase A mutants revealed that activation of detergent-resistant phospholipase A was essential for the export of cloacin DF13 across the outer membrane and the lysis of induced cells. Transport of cloacin DF13 across the cytoplasmic membrane was mainly dependent on protein H. A revised model for the excretion of cloacin DF13 is presented.

Bacterial Proteins↗

PubMed1985

Transcription of a transposed trypanosome surface antigen gene starts upstream of the transposed segment.

The non-telomeric variant surface glycoprotein (VSG) genes in Trypanosoma brucei are activated by a duplicative transposition to a telomeric expression site. We have determined the 5' end of the transposed segment of the gene for VSG 117 and infer from comparison with similar data obtained by others that the crossover can occur at variable positions within short repeats present upstream of this gene and in the expression site. We have analysed nascent and steady state transcripts of the transposed gene and its neighbouring expression site DNA. The results indicate that transcription starts upstream of the transposed gene segment in the expression site and that transcripts are rapidly processed at specific points identified by protection of DNA-RNA hybrids against digestion by nuclease S1 or Exo VII. Hence, this gene appears to be activated by a process akin to promoter addition.

Animals↗

PubMed1985

Production of monoclonal antibodies defining guinea pig T-cell surface markers and a strain 13 Ia-like antigen: the value of immunohistological screening.

The production and characterization of eight monoclonal antibodies (MAbs) against surface markers of guinea pig T-cells is reported. MAbs CT5 and CT7 define putative pan-T-cell markers. CT5, however, also reacts with the B-cell leukemic line L2C. MAb CT6 is reactive with less than 30% of peripheral T-cells. MAbs CT1, 2, 3, 4, and 8 are reactive with lymphocytes, but not with germinal center B-cells. In addition to the CT's, a MAb (CI-13.1) has been prepared that reacts with an Ia-like antigen on cells of strain 13 and outbred guinea pigs, but not with cells of strain 2 animals. CI-13.1 cross-reacts with human tissue sections: About 30% of the OKIa-positive dendritic cells in the human dermis are recognized by CI-13.1. In the course of production and characterization, various binding assays and an immunohistological method were used for determining the antibody specificity. Immunohistological screening was found to be the most informative method.

Animals↗

PubMed1983

Subcloning of the cloacin DF13/aerobactin receptor protein and identification of a pColV-K30-determined polypeptide involved in ferric-aerobactin uptake.

A plasmid containing a pColV-K30 fragment that encoded only for the cloacin DF13/aerobactin receptor protein was constructed. Escherichia coli cells harboring this plasmid were sensitive to cloacin DF13 but were unable to take up ferric-aerobactin. Another pColV-K30-determined polypeptide (molecular weight, 50,000), localized in the membrane fraction, was essential for the uptake of ferric-aerobactin.

Bacterial Outer Membrane Proteins↗