Natural cyclopeptaibiotics and related cyclic tetrapeptides: Structural diversity and future prospects

Linearity is not considered a prerequisite anymore, and extension of the current definition of 'peptaibiotics' to cyclic, Aib-containing peptides is proposed. Sequences and bioactivities, together with ecophysiological importance of cyclopeptaibiotics and related cyclic tetrapeptides, and their fungal-taxonomic relationships, are discussed.