Salt in the wound:: A possible role of Na+ gradient in chlamydial infection

Genome analysis has revealed the presence of key components of the Na+ chemiosmotic cycle, including the primary Na+ pump (Na+-translocating NADH:ubiquinone oxidoreductase), in the cytoplasmic membrane of two ubiquitous human pathogens, Chlamydia trachomatis and Chlamydiophyla pneumoniae. This observation seemed paradoxical in the case of obligatory intracellular parasites because the Na+ cycle is thought to be primarily a mechanism that enhances the adaptive potential in free-living bacteria that are often facing drastic changes in the salinity and pH of the environment. We present a model suggesting that operation of the Na+ cycle may play an important role in the course of chlamydial infection, when the Na+ and H+ homeostasis of the host cell become severely impaired. This introduces the intriguing possibility of the application of drugs targeting Na+-transporting enzymes to chlamydial infections, which are notoriously difficult to treat. Copyright (C) 2004 S. Karger AG, Basel.