Cleavage of tumor necrosis factor-alpha by Legionella exoprotease.
The role of the major secretory protein of Legionella pneumophila, a zinc protease, in Legionella infection is not known. Since an important step of the host reaction in Legionnaires' disease is the production of tumor necrosis factor-alpha (TNF-alpha) by alveolar macrophages, we studied the interaction of Legionella protease and U-937 cells with respect to TNF-alpha. The Legionella protease was purified by fractionated precipitation, gel filtration and hydrophobic interaction chromatography. The purified enzyme was added to U-937 cells, a promyelocytic cell line. In the supernatants of PMA-treated U-937 cells we found low concentrations of TNF-alpha after incubation with protease. Therefore we pursued the hypothesis of direct enzymatic degradation of TNF-alpha by Legionella protease. Enzymatic cleavage of TNF-alpha was proven by SDS-PAGE, ELISA and TNF-alpha bioassay with L-929 cells. The degradation of TNF-alpha by the Legionella protease was shown in all three systems. Enzymatic degradation of TNF-alpha might be important for the pathogenesis of Legionnaires' disease.
Hell
W
W
Institute for Medical Microbiology, Medical University of Lübeck, Germany.
Essig
A
A
Bohnet
S
S
Gatermann
S
S
Marre
R
R
D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D020689:Exopeptidases; D006801:Humans; D016952:Legionella pneumophila / Q000201:enzymology*; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism / Q000473:pathology; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D010447:Peptide Hydrolases / Q000378:metabolism / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
D014409:Tumor Necrosis Factor-alpha; D020689:Exopeptidases; D010447:Peptide Hydrolases