Editors' ChoiceMicrobiology

Cytosol, Salmonella, and pH

Science Signaling  25 May 2010:
Vol. 3, Issue 123, pp. ec156
DOI: 10.1126/scisignal.3123ec156

Salmonella and other bacterial pathogens grow inside animal host cells within intracellular vacuoles. The bacteria secrete effector proteins across the vacuole membrane, altering the host-cell physiology to the pathogen’s advantage. The secretion process involves a specialized secretory apparatus, the type III secretion system, whose assembly is triggered by the low pH within the host-cell vacuole. Now, Yu et al. (see the Perspective by Collier) have identified neutral pH as a physiological signal for effector translocation by intracellular Salmonella. The process involves the disassembly of a membrane-bound regulatory complex that is also found in other animal pathogens. Thus, Salmonella exploit the low pH of the vacuole as a signal to induce assembly of the secretion system, and then the neutral pH of the cytoplasm to trigger effector translocation.

X.-J. Yu, K. McGourty, M. Liu, K. E. Unsworth, D. W. Holden, pH sensing by intracellular Salmonella induces effector translocation. Science 328, 1040–1043 (2010). [Abstract] [Full Text]

R. J. Collier, Salmonella’s safety catch. Science 328, 981–982 (2010). [Summary] [Full Text]