A new direction for manganese homeostasis in bacteria: identification of a novel efflux system in Streptococcus pneumoniae.

The ability to control intracellular levels of transition metals such as Mn(2+), Fe(2+) and Zn(2+) is critical for the virulence of many pathogenic bacteria. In this issue of Molecular Microbiology, Rosch et al. describe the first identification of a Mn(2+) efflux system in bacteria, MntE of Streptococcus pneumoniae, and demonstrate that it is required for virulence in an animal model. Disruption of the mntE gene leads to widespread transcriptional changes that are distinct from responses to extracellular Mn(2+). These findings reveal, for the first time, that a bacterial trace metal efflux system plays a role in disease. Thus, MntE represents a new lead for the development of antimicrobials specifically aimed at disrupting microbial metal ion homeostasis.