Antimicrobial peptides and proteins in the face of extremes: Lessons from archaeocins

Archaeocins are ribosomally-synthesized antimicrobial peptides or proteins produced by archaea. Halocins and sulfolobicins are produced by archaea belonging to the order Halobacteriales (Euryarchaeota) and Sulfolobales (Crenarchaeota), respectively. These weapons contribute helping the producer to prosper in spite of the microbial warfare. Given the fact that many archaea thrive in various extreme environments, archaeocins are challenged with inhospitable and destructive environmental conditions. Their structural features and mechanisms of action, which could be original, mostly remain to be deciphered. This review summarizes the present knowledge on halocins and sulfolobicins, the two classes of archaeocins that have been evidenced until now, and brings light on aspects of emerging research such as their ecological role or potential applications. Other antimicrobial compounds produced by archaea are also considered.