C. Rouquette et al., IDENTIFICATION OF A CLPC ATPASE REQUIRED FOR STRESS TOLERANCE AND IN-VIVO SURVIVAL OF LISTERIA-MONOCYTOGENES, Molecular microbiology, 21(5), 1996, pp. 977-987
We identified a new chromosomal locus involved in the virulence of the
facultative intracellular pathogen Listeria monocytogenes. This locus
displays the same genetic organization as that of the clpC/mecB locus
of Bacillus subtilis. It contains a thermoregulated operon of four ge
nes, whose transcription is upregulated at 42 degrees C. The last gene
of this operon is clpC, which encodes a protein of 826 amino acid res
idues, identified as a ClpC ATPase, sharing a strong peptide sequence
identity (78%) with ClpC/MecB of B. subtilis. Tn917 insertions inactiv
ating the entire operon, or only clpC, gave mutants highly susceptible
to stress, including iron limitation, elevated temperatures and high
osmolarity. The virulence of these mutants was severely impaired in th
e mouse. A clpC insertional mutant was also restricted in its capacity
to grow in bone-marrow-derived macrophages. These results demonstrate
that the ClpC ATPase of L. monocytogenes is a general stress protein
involved in intracellular growth and in vivo survival of this pathogen
in host tissues.