Is the Ami-AliA/B oligopeptide permease of Streptococcus pneumoniae involved in sensing environmental conditions?

Streptococcus pneumoniae is a fastidious obligate parasite requiring several amino acids for growth. Oligopeptide uptake mediated by the Ami ABC permease is therefore important for nutrition but this could not account for the highly pleiotropic phenotype exhibited by Ami mutants. The hypothesis that peptide transport plays a pivotal role in sensing environmental conditions and indirectly modulates the expression of several genes is discussed.