Autoinducing

Autoinducing is an adjective describing a molecule or process that triggers the expression or activity of genes or pathways in response to its own presence, often via positive feedback. In microbiology, autoinducers are signaling molecules used in quorum sensing to coordinate behavior across a population of cells. These molecules are produced by the cells and accumulate in the environment as cell density increases. When their concentration crosses a threshold, they bind to specific receptors or regulatory proteins, leading to altered transcription of target genes. This enables coordinated behaviors such as bioluminescence, virulence factor production, biofilm formation, competence, or sporulation, depending on the species.

There are several classes of autoinducers. Gram-negative bacteria commonly use acyl-homoserine lactones (AHLs); Gram-positive bacteria typically employ autoinducing peptides (AIPs). A universally used signaling molecule is autoinducer-2 (AI-2), reported in many species and associated with interspecies communication. The term autoinducing can also apply to engineered systems in synthetic biology, where a gene product promotes its own expression through a feedback loop, enabling switch-like or bistable behavior.

Research into autoinducing systems informs approaches to disrupt pathogenic communication, modulate beneficial microbial communities, and design programmable genetic circuits. Limitations include signal crosstalk between species, environmental degradation of signals, and context dependence of regulatory responses.