Figure 2.
Hierarchical quorum-sensing (QS) network in Pseudomonas aeruginosa. The four QS pathways are activated in response to the cell density and environmental stimuli, with four autoinducer synthases including LasI, RhlI, PqsABCDH and AmbBCDE that produce N-3-oxo-dodecanoyl-ʟ-homoserine lactone (3O-C12-HSL), N-butyryl-ʟ-homoserine lactone (C4-HSL), 2-heptyl-3-hydroxy-4-quinolone (PQS) and 2-(2-hydroxyphenyl)-thiazole-4-carbaldehyde (IQS), respectively. Note: the autoinduction is depicted in red arrows; the receptor for IQS is still unknown. The QS products are secreted through the cell membrane, that control the group behaviours and essential for the adaptation, survival and pathogenicity of P. aeruginosa. Abbreviation: CM, cytoplasmic membrane; OM, outer membrane.