Recent advances in bacterial polyamine transport systems

Abstract

Many bacteria take up external polyamines to optimize their growth and adaptation to the environment. Furthermore, cell-to-cell communication using polyamines recently reported requires export of polyamines and uptake or recognition of polyamine outside the cell. At physiological pH, polyamines are positively charged and hydrophilic and therefore cannot pass through hydrophobic cytoplasmic membranes. Consequently, a polyamine transporter is required for their uptake and export in bacteria. Seven polyamine transporters, that is, PotABCD, PotE, PotFGHI, PuuP, PlaP, CadB and MdtJI, have been reported in Escherichia coli, in which polyamine transporters have been well studied since the 1990s. Recently, a growing body of research on polyamine transporters of other bacteria, especially pathogenic bacteria such as Proteus mirabilis, Vibrio cholerae, Aggregatibacter actinomycetemcomitans, and Streptococcus pneumoniae, is underway guided by current understanding about polyamine transporters of E. coli. In this chapter, recent understanding in bacterial polyamine transport is outlined in addition to the overview of polyamine transporters in E. coli.