Cell-cell communication in gram-positive bacteria.

In gram-positive bacteria, many important processes are controlled by cell-to-cell communication, which is mediated by extracellular signal molecules produced by the bacteria. Most of these signaling molecules are peptides or modified peptides. Signal processing, in most cases, involves either transduction across the cytoplasmic membrane or import of the signal and subsequent interaction with intracellular effectors. Concentrations of signal in the nanomolar range or below are frequently sufficient for biological activity. The microbial processes controlled by extracellular signaling include the expression of virulence factors, the expression of gene transfer functions, and the production of antibiotics.