Chemical Molecules that Regulate Transcription and Facilitate Cell-to-Cell Communication

In this article we review cell-to-cell communication in three groups of organisms: bacteria, fungi, and the amoeba Dictyostelium. In particular, we concentrate on cell-density-dependent quorum sensing, which seems to have evolved independently on several occasions. The biologic and chemical properties of select systems are outlined, and the way they affect transcription, often via cross-genome interactions, is described for each of the three groups. Furthermore, we give a short overview of the methods that can be used to study quorum sensing. We also outline the general properties of quorum sensing systems, such as positive feedback and its link to starvation-dependent pathways.