Reduced virulence of a Listeria monocytogenes phospholipase-deficient mutant obtained by transposon insertion into the zinc metalloprotease gene.
A phospholipase-deficient mutant, termed JL762, was obtained from a virulent strain of Listeria monocytogenes by screening a bank of 5,000 Tn1545 transposon-induced mutants on 2.5% egg yolk brain heart infusion agar. As previously shown (J. Mengaud, C. Geoffroy, and P. Cossart, Infect. Immun. 59:1043-1049, 1991), the transposon insertion took place inside the gene mpl, which encodes a zinc metalloprotease. By Western blot (immunoblot) analysis, we showed that loss of phospholipase activity was associated with loss of a 29-kDa zinc-dependent phosphatidylcholine-phospholipase C (PC-PLC) in culture supernatant of JL762 and of EGD-SmR incubated with ion chelator. As the parental strain, JL762 still produced in supernatants approximately 33-kDa proteins antigenically closely related to the 29-kDa PC-PLC. These results strongly suggest that the zinc metalloprotease of L. monocytogenes might play a role in the maturation of the 29-kDa PC-PLC. Although the uptake and the intracellular growth of bacteria were not affected in vitro, we found that the virulence of mutant JL762 was strongly impaired in the mouse.
Raveneau
J
J
Faculté de Médecine Necker-Enfants Malades, Laboratoire de Microbiologie, Paris, France.
Geoffroy
C
C
Beretti
J L
JL
Gaillard
J L
JL
Alouf
J E
JE
Berche
P
P
D000818:Animals; D015153:Blotting, Western; D004251:DNA Transposable Elements; D005260:Female; D008089:Listeria monocytogenes / Q000201:enzymology / Q000235:genetics / Q000472:pathogenicity*; D008666:Metalloendopeptidases / Q000235:genetics*; D051379:Mice; D008813:Mice, Inbred ICR; D009154:Mutation; D010740:Phospholipases / Q000172:deficiency*; D011817:Rabbits; D014774:Virulence; D015032:Zinc
D004251:DNA Transposable Elements; D010740:Phospholipases; D008666:Metalloendopeptidases; D015032:Zinc