|
||
By


From the * Department of Cell Biology and The pore-forming toxin listeriolysin O (LLO) is a major virulence factor implicated in escape
of Listeria monocytogenes from phagocytic vacuoles. Here we describe the pH-dependence of
vacuolar perforation by LLO, using the membrane-impermeant fluorophore 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) to monitor the pH and integrity of vacuoles in mouse
bone marrow-derived macrophages. Perforation was observed when acidic vacuoles containing wild-type L. monocytogenes displayed sudden increases in pH and release of HPTS into the
cytosol. These changes were not seen with LLO-deficient mutants. Perforation occurred at
acidic vacuolar pH (4.9-6.7) and was reduced in frequency or prevented completely when
macrophages were treated with the lysosomotropic agents ammonium chloride or bafilomycin
A1. We conclude that acidic pH facilitates LLO activity in vivo.
Department of Microbiology and Molecular Genetics,
Harvard Medical School, Boston, Massachusetts 02115
This article has been cited by other articles:
| TABLE OF CONTENTS |
|