VACUOLES INDUCED BY HELICOBACTER-PYLORI TOXIN CONTAIN BOTH LATE ENDOSOMAL AND LYSOSOMAL MARKERS

Intoxication of mammalian cells with the vacuolating toxin (VacA) rele ased by Helicobacter pylori causes the formation of large acidic vacuo les containing the vacuolar ATPase proton pump and Rab7, a late endoso me marker. Here, we describe a novel subcellular fractionation procedu re, and we show that nanomolar concentrations of VacA induce a clear r edistribution of lysosomal membrane glycoproteins among endocytic comp artments. This redistribution is an early event in the process of cell ular intoxication by VacA and precedes the formation of macroscopic va cuoles. The absence of the cation independent mannose 6-P receptor and the presence of Rab7 and of lysosomal membrane proteins in the newly formed compartment suggest that the vacuolating toxin induces the accu mulation of a post-endosomal hybrid compartment presenting both late e ndosomal and lysosomal features.