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Chapter 59 : Characterization of GDSL-Hydrolases of the Lung Pathogen Legionella pneumophila
Legionella pneumophila possesses secreted phospholipase A (PLA) and lysophospholipase A (LPLA) activities which might be involved in bacterial virulence, because they represent tools for modification and lysis of host cell membranes and for the interference with the host signal transduction pathways. The L. pneumophila genomes Philadelphia-1, Paris, and Lens code for three members of the GDSL family of lipolytic proteins, namely PlaA, PlaC, and PlaD. The authors aimed to identify the factor which directly activates PlaC. Furthermore, they sought to characterize PlaD, the third L. pneumophila GDSL enzyme, and to compare the lipolytic properties as well as the capacity of L. pneumophila plaD mutants to multiply intracellularly with L. pneumophila wild type and plaA and plaC mutants. The PlaC-activating factor, characterized by its ability to enhance glycerophospholipid:cholesterol acyltransferase (GCAT) activity of PlaC expressed in Escherichia coli, was biochemically purified from the culture supernatant of an L. pneumophila 130b plaC mutant by anion exchange chromatography (AEX). The main protein in the activating fractions consistently was the zinc metalloprotease ProA. To investigate whether L. pneumophila Corby plaD could confer PLA and LPLA activities to E. coli, cell lysates as well as the culture supernatants from E. coli clones carrying plaD in trans were examined for hydrolysis of PLA, LPLA, and lipase substrates.
Key Concept Ranking
- Phospholipase A