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Infect. Immun., 04 1997, 1172-1180, Vol 65, No. 4
KA Grant, IU Belandia, N Dekker, PT Richardson and SF Park
A gene (pldA) encoding a 35.0-kDa protein with significant homology to the
Escherichia coli outer membrane phospholipase was identified upstream of an
operon encoding an enterochelin transport system in Campylobacter coli. The
results of this study suggest that this gene encodes an outer membrane
phospholipase A in C. coli. First, expression of the pldA gene product in a
PldA-deficient mutant of E. coli led to the restoration of phospholipase A
activity. The recombinant product also partitioned to the outer membrane,
suggesting that it may be similarly located in C. coli. Second,
heterologous overexpression in E. coli, followed by in vitro folding and
purification of C. coli PldA, resulted in pure protein which displayed
calcium-dependent lysophospholipase and phospholipase A activities in
vitro. Finally, mutants of C. coli in which the pldA gene had been
inactivated by allelic exchange were deficient in phospholipase A activity.
Phospholipases are associated with lysis of erythrocytes by a number of
bacterial pathogens. The pldA mutant was shown to have a reduced hemolytic
activity compared to the wild-type strain, suggesting a role for the
phospholipase A in the lysis of erythrocytes by C. coli. Since hemolysins
are intimately associated with the disease-causing potential of a number of
bacterial pathogens, it is likely that the phospholipase A plays some role
in Campylobacter virulence.
Copyright © 1997, American Society for Microbiology
Molecular characterization of pldA, the structural gene for a phospholipase A from Campylobacter coli, and its contribution to cell- associated hemolysis
Institute of Food Research, Reading Laboratory, United Kingdom.
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